25 min


Acanthamoeba keratitis is a rare but serious eye infection that is painful and sight-threatening. It affects the clear front surface of the eye (the cornea) which becomes painful and swollen (inflamed).

Acanthamoeba are usually found in soil and in water, for example in hot and cold tap water, swimming pools, hot tubs and sea water. In the UK, most people who get Acanthamoeba keratitis wear contact lenses. About 1 in 30,000 contact lens wearers become infected. It’s also possible to become infected after an injury to the cornea. Using tap water to clean or store contact lenses or having poor contact lens hygiene increases the risk of infection. Examples of poor lens hygiene are not using disinfection solutions properly, reusing the solution in the contact lens case, failing to empty and dry the contact lens case after use and storing lenses in water overnight. Wearing contact lenses when swimming or taking a shower also increases risk. So does putting lenses in with wet hands from tap water.

Acanthamoeba keratitis is very painful for most people but it’s possible to have no pain at all. Other symptoms include red eyes that feel irritated or like they have something in them. Some people will get blurred or poor vision. Some people become sensitive to light and find it painful or uncomfortable.

Acanthamoeba keratitis needs immediate attention. Treatment is usually with antiseptic eye drops. It can be hard to treat and may also need antibiotics or steroids as well as painkillers. The most serious infections will mean the need for a corneal transplant. This involves surgery to remove the damaged cornea and replace it with a healthy one from a suitable donor.

Do make sure you have good contact lens hygiene. For example, clean and dry your hands well before touching your lenses. Take your lenses out before sleeping. Follow the advice from your optician and the manufacturer’s instructions for your lenses. Think about using daily disposable lenses instead of ones that need to be cleaned and stored to use again. Don’t wear contact lenses when you wash in the bath or shower, or when you go swimming at a pool or in the sea.

Achromatopsia is an inherited condition that affects the light-sensitive layer of the eye (the retina). It leads to faulty proteins in the retinal cells known as ‘cones’, which we need for colour vision. People with achromatopsia have poor colour vision because the cones can’t communicate properly with other cells in the retina. In turn, this means the retina cannot pass information about colour on to the brain. Achromatopsia is sometimes known as ‘day blindness’ as symptoms are more noticeable in bright light. About 1 in 30,000 people are affected. In some cases not all the cones are faulty - this is called ‘incomplete achromatopsia’.

Achromatopsia is usually an inherited condition. Six genes have been linked to achromatopsia so far. In very rare cases, achromatopsia can be brought on by damage to the brain. This is known as ‘acquired achromatopsia’ (cerebral achromatopsia).

Achromatopsia is often noticed at birth or in early infancy (before 6 months) when the child is very sensitive to light (photophobia), has ‘wobbly’ eyes (nystagmus) and poor vision.

There is currently no cure for achromatopsia. Prescription glasses or contact lenses can improve vision. A dark tint to the glasses can help to ease photophobia.

Macular degeneration, also known as macular disease or [age-related macular degeneration (AMD)](https://mthk.com/blog/what-is-amd), causes loss of central vision as a result of damage to the macula – a tiny collection of light-sensitive cells found within the retina at the back of the eye. These cells are vital for seeing detail. Damage to the macula can’t be reversed. It’s the most common cause of permanent and severe sight loss in the UK, affecting around 600,000 people – this number is expected to more than double by 2050. There are two types of macular degeneration – ‘dry’ and ‘wet’. Dry macular degeneration tends to develop more slowly over time, while the wet form of the condition can cause rapid severe sight loss. If detected early enough, treatment can help prevent wet macular degeneration from getting worse, but there’s currently no treatment for dry macular degeneration. For both types, once damage has happened, it’s irreversible. This is why funding vital research into macular degeneration plays a big part in our mission to create a future everyone can see.

Macular degeneration happens when cells within the macula, a tiny area within the retina at the back of the eye, have become damaged and scarred. These cells are photoreceptor cells, which means they’re sensitive to light and play a vital role in our ability to see details and colour. Macular degeneration only affects central vision, so peripheral vision (the outer edges) isn’t lost. But losing central vision means you can’t see things when you’re looking straight at them, so it can have a huge impact on day-to-day life. Exactly why some people develop macular degeneration while others don’t is not yet clear, but a number of risk factors have been recognised. Age is the biggest risk factor – the condition is mostly diagnosed in people aged 65 and over, although it can occur in younger adults too. More women are affected than men (but it’s believed this is largely because women tend to live longer) and people of African descent are generally less at risk. Macular degeneration can sometimes run in families too, although it’s not always inherited. Smoking is known to be a key risk factor, and studies have also linked obesity with a higher risk of macular degeneration. Other research has suggested that diet, and damage from high levels of sun exposure, may play a role – but the extent of these links isn’t fully established.

Macular degeneration doesn’t cause pain or affect the appearance of the eye, so symptoms usually start with noticing changes in vision. These can develop very slowly or rapidly (either way, it’s vital to get symptoms checked immediately). One or both eyes can be affected, although most people diagnosed will eventually have macular damage in both eyes. Visual changes may be slightly different for everybody, but these are the signs and symptoms typically associated with the condition: Difficulty seeing details. People may find it increasingly difficult to read small print and see clearly while driving, or see what’s happening on the TV screen, for example. Reduced central vision. The centre of somebody’s vision may become blurry, smudged or, when damage is more severe, a blank or dark spot may develop. Distorted lines. For example, straight lines may appear wavy or crooked in the middle. While reading, the lines in the middle of the page may become very blurred and distorted. Changes in colour perception. People may notice their perception of colour is decreasing and colours aren’t as vibrant as they used to be.

Macular degeneration is usually diagnosed following routine eye tests. Alongside testing a person’s vision and asking about any changes they’ve noticed, an optometrist will look at the back of the eye using a special light and microscope to check for signs of damage. If symptoms are severe or progressing or significant damage is detected, patients will be referred to a specialist (ophthalmologist) for further tests, including a scan of the retina - called an optical coherence tomography (OCT). Sometimes, a procedure called a fluorescein angiogram may also be carried out – this involves injecting a special dye into the arm which then travels to the blood vessels in the eye, enabling the specialist to examine them more closely. Getting diagnosed as early as possible is vital, as damage to the macula can’t be reversed. This is especially important for wet macular degeneration, which requires an urgent referral to a specialist. National guidelines suggest that a patient referred with possible wet AMD to a hospital specialist should be seen within 2 weeks of referral.

There is currently no treatment for dry macular degeneration. Regular check-ups and tests can help monitor changes. There’s also some evidence that, in some cases, diet or supplements may help slow down the progression of macular damage. Vitamins A, C and E, zinc, copper and lutein have been associated with possibly slowing dry macular degeneration. Specifically formulated supplements are available, but further investigation into the role nutrition plays is needed. It’s best to speak to your GP who can give you personalised advice. They are not currently available on prescription. Treatments are available for wet macular degeneration – but while effective at preventing further damage, they can’t ‘undo’ damage that’s already occurred, so starting treatment as early as possible can make a big difference. This usually involves injecting a special formula into the eye, which stops the unhealthy blood vessels from growing and causing further damage. Anaesthetic drops will be applied first, so the procedure isn’t painful. Laser therapy may also be suitable in some cases.

Amblyopia (or ‘lazy eye’) is a condition in which one or both eyes have poor vision without there being a problem with the physical structure of the eye itself. It’s the most common problem with vision in children. About 2-3 per 100 people are affected.

Amblyopia happens when the brain ignores one eye and relies more heavily on the other. This is usually because of a difference in glasses prescription between the two eyes – the brain prefers the eye with the naturally sharper vision. Another cause is strabismus (squint), when the eyes are not aligned. When this happens, the visual parts of the brain don’t get normal input as the child grows up. It can lead to permanent sight loss if left untreated.

Symptoms of amblyopia include problems judging depth or distance. It may be difficult to sense contrast or motion. This can make people clumsy or make it hard to play sports or catch a ball. There may also be psychological effects, such as lower self-esteem. Children with amblyopia may also be more at risk of being bullied.

At the moment treatment involves wearing corrective glasses and wearing a patch on the ‘good’ eye for a few hours a day until the visual development is complete. This means the brain has to use the ‘bad’ eye. Alternatively, eye drops can be used to blur vision in the good eye. Current treatments are more successful the younger the child is when the problem is picked up.

Aniridia is a very rare eye condition in which the coloured part of the eye (the iris) does not fully develop and there are other associated eye problems. It affects 2 in every 100,000 people. Most people with aniridia also have an under-developed fovea, which is a dip in the centre of the macula – the part of the light-sensitive layer of the eye (the retina) that we use for detailed, colour vision. Later in life, people with aniridia may develop other eye problems such as glaucoma, cataract and 'corneal opacification', where the usually clear front surface of the eye (the cornea) becomes cloudy. The lens in the eye is often cloudy, too.

Around 2 out of 3 people with aniridia inherit a faulty version of the gene PAX6 that has been passed down through the family. About 1 in 3 people have no family history of aniridia but develop a fault with PAX6 in the womb. In a few cases (about 2 out of every 100 people with the condition), aniridia is linked to the inherited disorder known as Gillespie syndrome, that affects balance, movement and mental ability.

Soon after birth (at around 6 weeks old) people with aniridia will likely have involuntary eye movements (nystagmus). Trouble focusing (refractive error) and eyes that point in different directions (strabismus) are also common. People with aniridia may also have drooping eyelids (ptosis). The main threats to sight in people with aniridia come from glaucoma and also from the lens and cornea becoming cloudy, reducing the amount of light that reaches the retina. Vision may be hazy or blurred and the field of view may become more narrow over time. The cornea may be painful.

Treatment for aniridia can include eye drops to reduce high pressure in the eye and prevent glaucoma from getting worse. It may also include a corneal transplant to reconstruct the front of the eye. Any cataract in the eye may need to be removed and replaced with an artificial lens made of plastic.

Anophthalmia means that people are born with no visible eye. People with microphthalmia are born with very small eyes, below a certain size, that also have structural problems. Up to 11 in every 100 blind children have either anophthalmia or microphthalmia. One or both eyes may be affected and both conditions lead to severe sight loss.

Several genes have been linked to anophthalmia and microphthalmia in recent years. But we don’t know exactly how they work or how they lead to eye defects. There are still more genes to find, but in some cases it may not be possible to find the exact cause. Most people don’t have a family history of the conditions. A prenatal test may be available for families who are at risk.

People with anophthalmia or microphthalmia will be blind or have some degree of permanent sight loss in one or both eyes. The disorders are often linked to other problems including brain malformations, cleft palate and cleft lip.

It is not possible to improve vision in the affected eye/s, so treatment for anophthalmia and microphthalmia is about reducing discomfort, and improving social well-being and facial appearance. Children may be given long-term genetic counselling and may have surgery to expand the eye socket. A prosthetic eye (‘false eye’) may be fitted if it helps.

Behçet syndrome is a serious long-term condition in which the blood vessels (arteries and veins) are swollen (inflamed) all through the body. More than half of people with Behçet have inflammation in the eye (uveitis). About 2 in 10 people with Behçet develop permanent sight loss.

We don’t know the exact cause of Behçet syndrome, but is classed as an ‘autoimmune’ disorder. This means that the body’s own defence system for fighting infection turns on its own body. The risk of getting Behçet syndrome may be increased by the combination of having certain genes together with environmental triggers such infection with a particular virus. Behçet syndrome is rare in the UK. It is more common in people from Turkey, Iran, Iraq, Japan and Korea.

Eye symptoms can include blurred vision, pain and redness. If there is inflammation at the front of the eye (anterior uveitis) symptoms will include painful, red eyes and being less able to see clearly (poor visual acuity). Inflammation at the back of the eye (posterior uveitis) doesn’t hurt but visual acuity gets worse and you may see ‘floaters’ across the field of view. In rare cases Behçet can affect the specialised cable that sends visual signals from the eye to the brain (the optic nerve). This can be sudden, with symptoms including poor colour vision, visual acuity or a black spot in the middle of the field of view (central scotoma). But visual loss usually happens slowly if the optic nerve is involved. Symptoms also affect other parts of the body including the mouth, heart, lungs, bowel, brain, joints and skin.

At the moment, the aim of treatment for Behçet syndrome is to reduce discomfort and prevent serious complications. There is currently no cure for Behçet's. Medications such as corticosteroids can be given to help suppress the immune system and reduce inflammation.

Best disease (otherwise known as vitelliform macular dystrophy) is an inherited condition that causes progressive sight loss. It is a form of juvenile macular degeneration, which means it starts in childhood and affects the central part of the retina (the light-sensitive layer at the back of the eye) which is known as the macula. We use the macula for seeing in detail.

Best disease is caused by faults in a gene called BEST1. More than 100 different faults have been discovered so far. There are several forms of Best and they can be passed on through families in different ways depending on which faults in BEST1 are involved. Some people inherit faults that cause what’s known as ‘autosomal recessive’ Best disease. If so, their own children may be ‘carriers’ who never develop symptoms but can pass the affected gene on to their children. Other people may have ‘autosomal dominant’ Best disease. There is a one in two chance that a parent with this type of Best will pass the condition on to their child

Best disease causes the retina to detach from its support layer (retinal detachment). Symptoms can start from the age of 3 and slowly become worse over time. It gradually affects the ability to see straight ahead and can lead to a blank spot in the centre of the field of view. Vision may be blurred and colours can appear less distinct.

There are currently no treatments for Best disease. There are training methods available to help children with Best disease and other forms of macular degeneration with their reading.

Birdshot is a rare condition that is hard to treat and may lead to blindness. It affects the choroid and retina. The retina is the light-sensitive layer of the eye, and the choroid is a layer of blood vessels that supplies the retina. Birdshot is also known as ‘Birdshot uveitis’ because the choroid is the back part of the inner lining of the eye (the uvea). The word uveitis means inflammation in the uvea.

Birdshot is thought to be what's known as an auto-immune disorder. This means that the body's defence system for fighting infection (the immune system) starts to attack parts of its own body. Most people with Birdshot test positive for HLA-A29 - one particular version of a gene that's important for the immune system. But not everyone who tests positive will develop Birdshot, so there must be other factors that put people at risk. Almost everyone with Birdshot is white, and most are female and aged 40-60.

The main symptoms of Birdshot are reduced vision, seeing floaters, night blindness, problems with colour vision, glare and seeing flashes of light.

About 2 in 10 people with Birdshot have symptoms that get better on their own without treatment. But the condition may flare up again repeatedly. There are several options for treatment if it's needed, but everyone responds differently and what works for one person may not work for someone else. Treatment usually begins with steroids, taken by mouth, to reduce inflammation and suppress the immune system. Extra medication to suppress the immune system may also be needed. Vitamin D and calcium supplements may be given to help with the side effects of taking high doses of steroids, which include weakening of the bones (osteoporosis). Other side effects of steroids can include bruised skin and stomach irritation. Side-effects in the eye include cataract (when the lens in the eye turns from clear to cloudy). Cataract can be treated with surgery to replace the cloudy lens with an artificial one. In the long term, treatment may involve newer medications (known as biologics) that target specific parts of the immune system. These may be given by injection or drip. Sometimes a combination of treatments works better than one type of drug alone.

Just behind the iris (the coloured part of the eye) is the lens. The lens helps focus light onto the retina (the light-sensitive layer at the back of the eye). Lenses need to be clear (transparent) to let the light pass through. A cataract is the name for a lens that has become cloudy.

Cataract is a common condition most often seen in older age as part of the normal ageing process, but can happen at any age. Some rare inherited conditions mean that babies will be born with cataract. Cataracts develops due to the proteins of the lens changing their arrangement and clumping together which causes the clear lens to become cloudy, which means light is unable to pass through it directly. Other causes of cataract include diabetes, eye injury and use of steroid eye drops or tablets. Cataract is also often seen together with other eye conditions.

Cataract causes blurred or hazy vision, which may appear ‘washed out’, with less contrast between black and white. Bright lights such as car headlamps might cause glare or dazzle, especially at night. Colours can also seem altered or more yellow. As cataract can affect each eye differently, some people will notice different vision in one eye compared to the other. Cataracts gradually get worse over time. Sometimes progression happens so slowly that the person with cataract doesn’t notice the sight loss. Cataract is not painful but can cause blindness if left untreated.

Cataract surgery is very successful and serious complications are rare. At the moment, cataract can only be treated with surgery. It is the most common operation in the developed world. This very delicate operation involves removing the cloudy human lens and replacing it with a new artificial plastic lens. In the UK, most people who have the operation are in their mid-70s. It takes about 30 minutes and is usually done under local anaesthetic as a day case. Cataract surgery is very successful and serious complications are rare.

Cataract cannot be treated, slowed down or prevented with medicine or eye drops. Watching TV or computers does not cause cataracts. Some population studies suggest that stopping smoking and wearing sunglasses with UV protection may help prevent cataract or slow down its progress. But there is no evidence that these, vitamins, diets or changes in life style are of benefit to individual people.

Cerebral visual impairment is the name for problems with vision that stem from the brain rather than the eye. Our eyes turn light from the world around us into electrical signals. The signals are sent along connections between nerve cells (‘the white matter’) to many different areas in the brain (the cerebrum). The visual brain uses these signals to piece together different aspects of what we see. It works out what an object is, where it is, whether it’s moving or whether we’ve seen it before. Damage to the visual brain and its connections (the visual pathway) leads to different problems depending on where it is. For example, someone with cerebral visual impairment might not be able to see anything in the top left of the view ahead, or might have trouble recognising faces.

There are several causes of cerebral visual impairment. It may be part of a wider neurological condition that affects thinking, movement, or other senses such as hearing or touch, and may happen in people with epilepsy. Lack of oxygen to the brain in premature or full-term babies can damage white matter. Infection, such as meningitis or encephalitis, can also damage brain tissue, as can head injury. Cerebral visual impairment may also follow brain surgery, for example to cure epilepsy or remove brain tumours, if part of the visual pathway is damaged in the process.

Common signs and symptoms of cerebral visual impairment include - being sensitive to light (photophobia) or staring into light (light-gazing) - not looking into people’s eyes (poor ‘social gaze’) - never fixing on objects for long - trouble with smooth eye movements, e.g. to follow moving objects - not doing well on sight test charts (poor visual acuity) - only seeing some parts of the world ahead (visual field loss) - being clumsy with objects, e.g. reaching past them, knocking them over, bumping into things - getting tired doing tasks that need vision - seeing moving objects better than still (static) ones - seeing colour better than black and white - trouble recognising familiar people or places - trouble picking out one item when lots of items are in view - finding it harder to see when it’s noisy

There is no treatment or cure for most types of cerebral visual impairment. However, several things may help people to see better. If glasses or contact lenses are needed (for example to correct short-sightedness), they will help the light that gets turned into electrical signals to be as clear and focused as possible. This is especially important for children as the brain grows and develops. Large, widely spaced print, using a computer and using a ‘letterbox’ to see one word at a time can make reading easier. Using other senses, such as sound and touch, and removing distractions from the environment may also help.

Charles Bonnet syndrome (CBS) is a common side-effect of sight loss in which people see things that are not there (visual hallucinations). The hallucinations can be very clear, detailed and consistent and can happen to people with good mental health. There is currently not enough data to show how many people in the UK have Charles Bonnet Syndrome, but it is estimated to be hundreds of thousands, with some experts even putting the number as high as one million.

We don't know exactly what causes Charles Bonnet syndrome but it's more likely with severe sight loss or blindness, especially in both eyes in older people when people are socially isolated after vision gets worse suddenly Although eyes are the sensors that respond to light, it's the brain that does the seeing. The brain receives information from the eyes and decodes it into the picture we see. If the brain stops receiving information, it can fill in the gaps with its own images. So it's possible that Charles Bonnet syndrome is similar to the feeling of having a 'phantom limb' that can be experienced by people who lose an arm or a leg. If you have Charles Bonnet syndrome it does not mean that you have dementia or a serious mental illness.

The kinds of things people see with CBS is thought to fall into two main types: 1) simple repeated patterns or shapes, such as grids or brickwork patterns 2) complex hallucinations of people, objects and landscapes. These can vary from benign to quite alarming - for example, some people report seeing ‘snakes crawling out of people’s heads’ others see children in Victorian dress. Charles Bonnet syndrome hallucinations can be very detailed, and much clearer than the person’s everyday vision. The images appear very suddenly, lasting for just a few minutes or in some cases, several hours. The condition can cause huge distress to people who experience it, and can greatly impact on quality of life. The hallucinations may happen less often as time goes on. People experiencing the hallucinations will usually know that what they are seeing is not really there. Other senses, such as smell, hearing, taste and touch are not affected. Charles Bonnet syndrome can happen to people with good mental health who have no history of psychiatric problems. Usually, people with CBS are aware – or can learn to recognise – that what they’re seeing isn’t real even though it’s very vivid.

At the moment there is no specific cure for Charles Bonnet syndrome, but it is possible to make it easier to deal with. It can help to understand that the hallucinations are a normal result of sight loss and not a sign of mental illness. It may also be helpful to talk to family or friends and to your GP or eye doctor, especially if the hallucinations are getting in the way of day to day life. Medications may help if the hallucinations are distressing. There may also be some simple practical things to do when they start such as changing the lighting or what you are doing at the time. Eye movements can help stop a troubling hallucination while it occurs.

Choroideremia is a rare genetic eye condition that almost always affects males. Its symptoms usually start in childhood, with a person experiencing progressive vision loss due to a gradual loss of cells in and around their retina, the specialised light-sensitive layer that lines the back of the eye. This is a consequence of damage to the network of blood vessels (the choroid) that supplies the retina with the vital nutrients and oxygen that it needs to remain healthy. Choroideremia is estimated to affect between 1 in 50,000 to 100,000 people in the UK. However, the condition is likely to be underdiagnosed as its symptoms are similar to several other eye conditions, such as retinitis pigmentosa.

Scientists have discovered that choroideremia is caused by faults in a single gene known as CHM. This gene provides instructions for making a protein called REP-1, which plays an essential role in cells in the retina at the back of the eye. Faults in the CHM gene lead to either an absence of REP-1 or a version that can’t carry out its normal function – and in turn, this leads to the damage to eye tissue that is found in patients with the condition. The CHM gene can be inherited and passed down through families. Males are much more likely to develop the condition, but females can pass the faulty CHM gene on to their children.

Difficulties with seeing in the dark – or night blindness – is one of the earliest symptoms of choroideremia, which most commonly appears in boys during childhood. As a person’s condition progresses, they will start to develop sight loss that gets worse over time. This can often initially start as an irregular ring that gradually expands both inwards and outwards. They may also experience other visual symptoms including loss of sharpness, depth and colour perception. Eventually, they will develop complete blindness that usually occurs in adulthood around 20 to 30 years after symptoms began. However, the speed that the condition progresses and the degree of sight loss varies widely from person to person – and even between affected members of the same family. Females who carry the faulty CHM gene will usually not have any sight loss. However, they may experience mild symptoms later in life, such as night blindness and sensitivity to glare.

An ophthalmologist (hospital eye doctor) will perform tests to examine the person’s visual field and look for signs of distinctive problems affecting their retina at the back of the eye. Genetic testing to identify faults in the CHM gene can help to confirm the clinical diagnosis, along with a family history that is consistent with an X-linked inheritance pattern.

Unfortunately, there is currently no cure for choroideremia – but recent gene therapy research advances, initially funded by Fight for Sight, are fuelling the development of potential new treatments, providing hope for the future. Wearing protective sunglasses outdoors may help to protect vision by reducing exposure to ultraviolet (UV) light, which can theoretically cause further retinal damage.

Ocular coloboma (or just ‘coloboma’) means that there is a gap at the base of the eye. It’s rare – about 1 in 10,000 births are affected – but it accounts for up to 10 percent of childhood blindness. Coloboma happens during pregnancy (at around 6-8 weeks). The lower-most parts of the light-sensitive layer of the eye (the retina) fail to develop properly. Instead of fusing together, there is a gap which can extend from the coloured part of the eye at the front (the iris) through to the specialised cable that sends visual signals from eye to brain (the optic nerve) at the back. It can affect one or both eyes and may be more severe in one eye than the other. It is usually diagnosed in newborn babies.

Doctors and scientists think that coloboma is mainly genetic, but in many cases the genetic fault has not been discovered. This means we still know very little about the precise causes of coloboma, but it’s likely that environment (e.g. lifestyle and infections during pregnancy) may also play a part. Coloboma can happen when there is no family history of it, or it can be inherited. It may also be part of syndromes that affect other parts of the body and linked to additional eye conditions. Parents of children with coloboma are often examined to see if they also have a mild version of it, to find out if it was inherited.

If the gap extends back into the eye it can severely affect vision, especially if it affects the retina and optic nerve. But many people with coloboma may not know that they have it, as there may not be any symptoms. The most common form of coloboma does not affect vision – the only sign of it is a keyhole-shaped gap in the iris.

There are no treatments yet for sight loss due to ocular coloboma of the retina or optic nerve. But support can be given to help people make the best use of the vision they have. The affected eye may need to be protected from damage by direct sunlight. A full ophthalmological examination is usually done if coloboma is suspected at birth.

The conjunctiva is a part of the eye that covers the white of the eye and lines the inside of the eyelid. Irritation or damage to this surface can lead to conjunctival disease.

The conjunctiva can be damaged by injury, infection, chemical irritation, allergic reactions, dry eye and, rarely, by cancers. Inflammation in the conjunctiva is known as conjunctivitis. Inflammation may be caused by infection (such as trachoma) or by an ‘auto-immune’ response in which the body attacks itself with the system that usually fights off infection. Age can also lead to the conjunctiva becoming loose and developing folds.

Symptoms of conjunctival disease may range from redness and irritation to discharge, swollen eyelids, a burning sensation and pain. Some conjunctival conditions can cause significant scarring. The eyelids can become stuck to the eye and cause sight loss because of damage to the cornea (the clear front surface of the eye).

Treatment for conjunctival disorders will depend on the condition and the exact symptoms. Options may include antibiotics, steroids and other anti-inflammatories, eye drops and surgery.

The cornea is the clear front surface of the eye. A corneal disease is any condition that affects the cornea and blocks some or all light, reducing vision.

Corneal disease may be caused by damage from: - scratches or sharp objects - chemical injury - infection (including viruses, bacteria and fungi) - inherited disorders that change the cornea’s shape or thickness - other health conditions such as rheumatoid arthritis

Damage to the cornea may cause reduced vision, redness, pain or discharge. Infectious corneal ulcers are generally very painfu

Treatments for corneal disease will depend on the specific cause and may include eye drops, antibiotics and vitamins. But there are limited options. One option is to have a corneal transplant. This involves surgery to remove the damaged cornea and replace it with a healthy one from a donor. Thanks to the generosity of our supporters, we have been able to establish the UK Corneal Transplant Service. This has enabled over 52,000 transplants. Unfortunately there is a huge shortage of donors. This means that only a few of the 1.5 million people each year who could benefit from a corneal transplant are able to have one.

Wearing safety glasses or protective goggles can shield the eye from injury when working with hazardous or airborne materials. This may also work for certain sports or activities at home such as DIY, gardening or setting off fireworks. People who wear contact lenses are at special risk of corneal infection. Good contact lens hygiene is vital, for example not sleeping in lenses and always using the proper cleaning solution. Never shower or swim in contact lenses.

Corneal dystrophy is a group of rare inherited eye conditions that affect the cornea – the clear front surface of the eye – and can cause sight loss. The group includes Fuchs corneal dystrophy and Meesmann Corneal Dystrophy.

Corneal dystrophies are inherited, which means they are passed down through families. But we don’t know the exact genetic cause in many cases.

Corneal dystrophy leads to the cornea becoming less and less clear over time. This can eventually mean complete sight loss.

Corneal dystrophies often require a corneal transplant to restore vision. This involves surgery to remove the unhealthy cornea and replace it with a clear and healthy donor cornea.

Diabetic retinopathy is a form of sight loss that can develop in anybody with type 1 or type 2 diabetes, as a result of damage to blood vessels supplying the retina - the light-sensitive layer at the back of the eye. There are different types and stages of diabetic retinopathy, which can vary in severity and, in some cases, lead to blindness. It is one of the most common cause of sight loss among working-age adults in the UK. With rates of diabetes on the rise this figure is expected to increase. Managing diabetes well can help prevent diabetic retinopathy and if detected early enough, treatments including injections and laser surgery can help. But in the early stages blood vessel damage doesn’t always cause noticeable symptoms. So it may go undetected until the problem gets worse, which means complications and permanent sight loss can still occur. This is why funding vital research into diabetic retinopathy plays a big part in our mission to create a future everyone can see. Fight for Sight’s goal is to understand more about the processes involved with diabetic retinopathy and develop new treatments – to help save thousands of people from diabetes-related sight loss.

Diabetes affects how the body regulates blood sugar (glucose) levels. When these are too high, blood vessels throughout the body can become damaged, which can result in serious complications. Diabetic retinopathy results from damage caused by diabetes to the blood vessels that supply oxygen to the retina – which is responsible for converting light passing through the eye into the signals sent to the brain that enable us to see. However, exactly how and why these changes happen is not yet fully understood. The three main stages of diabetic retinopathy are: **Stage 1: Background diabetic retinopathy** Background diabetic retinopathy is the earliest detectable stage, when small swellings develop in the capillaries (tiny blood vessels). These don’t normally affect vision but monitoring them closely is important. **Stage 2: Pre-proliferative diabetic retinopathy** At this stage more widespread changes are seen in the retina, including severe bleeding into the retina. There is a high risk that your vision could eventually be affected. **Stage 3: Proliferative diabetic retinopathy** This is an advanced stage of diabetic retinopathy, which develops when blood vessels have become severely blocked or damaged. In response, the body begins to produce new blood vessels - but these are often very weak and prone to bleeding, which can cause scarring to form. Leaked blood can also block light from reaching the retina, resulting in sight loss. Proliferative diabetic retinopathy can sometimes lead to retinal detachment, where the retina peels away from the back of the eye. **Diabetic maculopathy** If these swellings worsen, blood vessels can begin to leak. Diabetic maculopathy occurs when leaking fluid has damaged the macula – a tiny collection of light-sensitive cells at the centre of the retina. The macula is crucial for central vision and seeing detail and colour, so macula-related sight loss can have a big impact. Not everybody with diabetes develops retinopathy. But it is one of the most common complications of the condition - and the longer you’ve had diabetes, the greater the chance of developing it. Within 20 years of diagnosis, nearly everyone with diabetes will be affected to some degree. People whose diabetes is well managed are less likely to develop retinopathy than those whose blood sugar, blood pressure and cholesterol levels are poorly controlled. Those who smoke are at higher risk. Proliferative diabetic retinopathy also tends to be more common in people with type 1 diabetes than type 2. And ethnicity can play a role: People of Afro-Caribbean and South Asian heritage are about twice as likely to develop sight-threatening diabetic retinopathy as white Europeans.

Vision isn’t usually affected during early stages of blood vessel damage. If the condition worsens, how it affects vision can vary from individual to individual. When diabetic retinopathy does cause symptoms, they may include: - Reduced central vision. This may be mild to begin with but can gradually worsen over time. Vision may become blurred and patchy, which might be most noticeable with tasks that involve seeing detail - like reading, watching TV and using a computer – due to damage affecting the macula. - Changes in colour perception. People may notice colours aren’t as clear and vibrant as they used to be. - Floaters. An increase in floating shapes or dark spots in your field of vision can also occur. - Eye pain. Diabetic retinopathy doesn’t always cause pain but any eye pain and/or redness should be assessed immediately, as it could be a sign of serious complications. - Sudden severe sight loss or vision changes. Retinal detachment is a rare complication of diabetic retinopathy, but when it occurs symptoms can come on suddenly. This may involve a dark ‘curtain’ moving across your field of vision, or a sudden dramatic increase in floaters or seeing flashing lights. Retinal detachment is a medical emergency that should be assessed urgently.

In the UK, everybody with diabetes is offered routine annual health checks to monitor how well their diabetes is being managed and pick up any early signs of problems. This includes eye examinations (diabetic eye screening). During a screening, eye drops will be applied to temporarily dilate the pupils, before a special camera is used to take photos of the back of the eye. Depending on the findings, more regular monitoring may be advised, or people may be referred for further tests and treatment.

How diabetic retinopathy is treated depends on the severity of the condition. First and foremost, the focus is on preventing blood vessel damage through good diabetes management. Even if early signs of damage are detected during a routine screening, taking steps to better control blood sugar levels can help stop problems from getting worse. If treatments are required, they may include: **Eye injections** Anti-VEGF injections can be used to treat diabetic maculopathy. Local anaesthetic is used to numb the eyes, before the treatment is administered by a specialist via a very fine needle. As well as preventing further damage, when suitable, anti-VEGF injections may help restore sight loss that’s already occurred in some patients. **Laser treatment** Lasers can be used to treat new weak blood vessels that develop as a result of diabetic retinopathy. The laser can help seal and remove the damaged vessels, preventing them from bleeding and causing further sight loss. This is usually carried out as an outpatient procedure, with local anaesthetic used to numb the eyes first. **Surgery** In severe cases, surgery may be required. This may include surgery to repair a detached retina, or vitreoretinal surgery to remove some of the vitreous humour (the clear jelly-like substance that fills the space between the lens and the retina). This may be required if leaky blood vessels have resulted in significant bleeding, resulting in scar tissue, blockages and a high risk of retinal detachment. Surgery is carried out under general anaesthetic and involves a specialist surgeon making a small incision in the eye. However, treatment can’t always undo damage that’s already occurred. Side-effects can occur too, ranging from temporary irritation and blurred vision, to permanent sight loss.

Duane retraction syndrome (or just Duane syndrome) is an eye movement disorder. There are several types. In the most common type the affected eye cannot move outward fully. The other types of Duane syndrome affect inward movement or both inward and outward movement. Duane syndrome usually affects one eye only and is present from birth.

One of the nerves that controls how the eye moves outwards (the sixth nerve) doesn't form properly. The connections of another nerve (the third nerve) can also be affected, causing trouble with inward movement. In rare cases Duane syndrome is inherited. If so, it’s due to a faulty gene (CHN1).

People with Duane syndrome find it very hard to move the affected eye outwards towards the ear. When they try, the eyelid opening gets wider. It may also be hard to move the eye inward towards the nose. Most people with Duane syndrome only have eyes that look in different directions (a strabismus) when looking to one side. If so, they can compensate with a subconscious turn of the head and avoid it. About 3 in 10 people with Duane syndrome will have other conditions too, such as being born deaf or having problems with their backbone (spine).

Duane syndrome is not progressive so it doesn’t get better or worse. Most people with Duane syndrome don't need treatment because they can compensate by turning their head. If it's not possible to compensate with a head turn, or if the head turn that works means people have to hold their head in a difficult position, then surgery may be needed. The missing nerve cannot be replaced, so the aim of surgery is to move the affected eye to a more central position. This makes it easier to use a smaller head turn to get the eyes to fix on the same spot at the same time. Surgery cannot make eye movement easier.

Eyelid cancer is a term used for cancer that occurs on or in the eyelid. Cancer starts when cells change and start to grow uncontrollably, forming a tumour. A tumour can either be benign or malignant. A benign tumour is not considered to be cancerous although it can grow, it will not spread to other parts of the body. However, a malignant tumour can grow and spread to other parts of the body. Most eyelid cancers are skin cancers. As the skin in this area is very thin, it is easily damaged by sun exposure – and so it is a common place for these tumours to develop. Skin cancers most commonly occur on the lower eyelid, but they can also start on the upper eyelid, eyebrow or in the corners of the eye. Most eyelid cancers – around 9 out of 10 – are basal cell carcinomas. These are usually benign and most commonly affect people with fair or pale skin. Other rarer types include sebaceous cell carcinoma, squamous cell carcinoma, and melanoma – which can become life-threatening if they spread to other parts of the body.

The most important cause of eyelid cancer is exposure to ultraviolet (UV) radiation from the sun or other sources such as tanning beds. This can cause damage to the DNA of skin cells, which can trigger a cell to start to grow out of control, forming a tumour. Because the eyelid has the thinnest skin on a person’s body, it is very sensitive to this type of damage. People living in places with year-round bright sunlight and those who spend a lot of time outdoors or on tanning beds are at an increased risk of developing eyelid cancer. People with fair or pale skin have a higher chance of developing the disease compared to those with darker skin tones.

People may experience a range of symptoms or signs of eyelid cancer which can include: - Swelling or thickening of the eyelid skin - Chronic infection of the eyelid - A change in the appearance of the eyelid skin - A spreading, coloured growth on the eyelid that can be red, brown or black - Broken skin on the eyelid that doesn’t heal (ulceration) - Loss of eyelashes But sometimes people with eyelid cancer do not have any of these symptoms – or they may be due to another condition that is unrelated to cancer. If you have any of these symptoms – or any other changes to your eyes or eyelids – it’s important to get examined by your GP or an eye care professional.

An ophthalmologist (hospital eye doctor) will carefully examine any abnormality of the eyelid. To confirm a cancer diagnosis, they will need to perform a surgical biopsy that involves removing a tiny sample, or sometimes the whole tumour. They will then send this to the laboratory for microscopic evaluation for the presence of cancer cells. As some skin cancers are malignant, there is a risk that the disease may have spread beyond the eyelid to other parts of the body. In these cases, the doctor may recommend other diagnostic tests. These include imaging scans, or a sentinel node biopsy – which is a surgical procedure that is used to determine if the cancer has spread to the lymphatic system.

The sooner an eyelid cancer is diagnosed, the easier it is to treat successfully. The main treatment for most eyelid cancers is surgery to remove the tumour and a small margin of the healthy surrounding tissue. This will often be followed by reconstructive surgery to repair the damaged area and improve eye function. Other potential treatments include radiotherapy, topical chemotherapy drugs (usually eye drops or creams) applied to the affected area, or cryotherapy – the use of liquid nitrogen to freeze the tumour. Although it is rare, for some aggressive types of eyelid cancer it is necessary to remove a person’s whole eye to stop their disease from spreading to other parts of the body. Due to the sight loss caused by the removal of an eye, a person may experience trouble with their depth perception and may need additional support to help them to adjust to this change. If a person’s eyelid cancer is more advanced and has spread to other parts of their body, the treatment options include surgery, radiotherapy, chemotherapy, immunotherapy (which aims to boost the body’s own immune system to fight their cancer) and targeted drugs.

The cornea is the clear front surface of the eye. Fuchs dystrophy is one type of corneal dystrophy (a group of inherited disorders that affect the cornea). In the UK, Fuchs dystrophy often leads to corneal transplant surgery and is a fairly common cause of blindness worldwide.

The cornea has 5 different layers. Fuchs dystrophy affects the inner layer (called the endothelium). In a healthy eye the endothelium prevents fluid from entering into the cornea from the middle layer of the eye. But in Fuchs dystrophy, the cornea takes in fluid and swells. This makes the cornea become less clear, which affects vision. Fuchs dystrophy can be caused by an inherited genetic fault but may also happen in people with no family history of the condition.

Fuchs corneal dystrophy usually begins after the age of 40. Both eyes are simultaneously affected in almost all patients. Sight loss happens gradually and tends to be worse first thing in the morning. Later symptoms can include pain and eventually serious sight loss.

Fuchs corneal dystrophy may need transplant surgery to remove the damaged cornea and replace it with a healthy one from a donor.

Glaucoma is the name for a group of eye conditions that cause sight loss because of damage to the optic nerve – the nerve that connects the eyes to the brain. Around 60 million people live with glaucoma, making it the second leading cause of blindness worldwide. There are different types of glaucoma, and increased eye pressure and age are important risk factors. Damage to the optic nerve can’t be reversed. Glaucoma damage can be prevented if detected and treated early. However, sight loss is irreversible.

Glaucoma is often (but not always) linked to high eye pressure. Our eyes contain a fluid called aqueous humour, which helps them hold their shape. When this fluid no longer drains away fast enough, eye pressure can rise - but glaucoma can also occur in people with normal eye pressure. Why some people develop glaucoma and others don’t isn’t fully understood. Age is the most significant risk factor, with almost 10% of people aged 75 and over having glaucoma. Close family relatives and people from certain ethnicities (such as African, Caribbean, or Asian origin) will be at higher risk of developing certain types of glaucoma.

1. Primary open-angle glaucoma (POAG) is the most common form. It happens when the eye’s drainage channels gradually become clogged and tends to develop slowly over many years. It’s also the type most associated with older age. It is also slightly more common in people of African-Caribbean descent. 2. Acute angle closure glaucoma (closed-angle glaucoma) happens when eye pressure can rise very suddenly, potentially leading to acute damage to the optic nerve. It’s much less common than primary open-angle glaucoma and tends to affect people of East Asian origin more. 3. Secondary glaucoma occurs due to something else in the body or eyes, such as side-effect from certain medications, another underlying eye condition like uveitis (inflammation of the eye), or an eye injury. 4. Normal tension glaucoma is diagnosed despite eye pressure being normal. Why it happens isn’t entirely clear, but some people’s optic nerves may be more fragile. 5. Congenital glaucoma, also known as childhood glaucoma, is when the condition is present from birth due to an abnormality within the eye.

Glaucoma tends to develop slowly and often doesn’t cause noticeable symptoms until damage has already occurred. Sometimes people experience acute glaucoma, which causes a sudden onset of severe eye pain and blurred vision. When glaucoma does cause symptoms, these might include: - Blurred and reduced vision starts with peripheral vision (outer edges) and develops very slowly. - Seeing rings and rainbow-coloured circles around bright lights. - Severe eye pain that comes on suddenly. This might be accompanied by redness and tenderness of the eye and surrounding area, plus a headache, nausea and vomiting.

Glaucoma is usually diagnosed during regular eye tests. Tests for glaucoma often start with an eye pressure test. An optometrist will also examine the front part of the eye to see whether they can spot any issues with fluid drainages, such as a blockage. Visual field tests are also carried out to see whether there’s any loss of peripheral vision, and the optic nerve will be assessed too. This sometimes involves eye drops or an eye scan so the optometrist can look closely at the eye. Patients with suspected glaucoma will be referred to a specialist to confirm the diagnosis and assess the level of damage.

Glaucoma is treated by managing the underlying causes to prevent further damage to the optic nerve. The main treatment options currently available are: - Eye drops that reduce the amount of fluid produced in the eye or improve fluid drainage. - Laser treatment, under local anaesthetic as an outpatient, is a fairly standard procedure to help lower eye pressure. - Trabeculectomy is a surgical procedure only required in a small number of cases. A specialist surgeon will create a new drainage channel within the eye to improve fluid drainage.

Keratoconus affects the cornea, the clear round-shaped front surface of the eye. This becomes progressively thinner and weaker over time, eventually causing a cone-shaped protrusion to develop. The abnormal change of shape causes a person to have blurred and distorted sight as it prevents the light that enters their eye from being correctly focused. The condition is estimated to affect between one in 500 to 2,000 people worldwide. But it may be more common in certain populations. Most people who develop keratoconus have no family history of the condition. But it can occasionaly appear to run in families and also sometimes occur as part of another genetic eye condition, such as Leber congenital amaurosis or retinitis pigmentosa – or a broader inherited syndrome affecting many parts of the body such as Down’s, Marfan or Ehlers-Danlos syndromes.

Scientists do not understand exactly what causes keratoconus. But it is thought that many different genetic and environmental factors are involved. Several genes have so far been linked with keratoconus often in specific populations. Although these genetic variants can influence a person’s risk of developing the condition, whether they do so is determined by complex interactions between other genes and environmental triggers. Studying the function of these known risk genes is helping scientists to improve our understanding of the biology of keratoconus – and will hopefully lead to new prevention or treatment strategies. They have so far identified that these genes are involved in many diverse activities – including in eye development, the formation and structure of the cornea, the lattice of materials that fill spaces between cells, inflammation and in the control of cell growth. Scientists are also searching for environmental triggers that may contribute to the development of keratoconus. For example, around one-third of people with the condition also have an allergy. One theory is that allergies can cause itchy eyes – and this may lead to excessive rubbing over long periods of time, which could potentially weaken the cornea.

Keratoconus will typically begin in young people during their late teens or early 20s, with the changes in the eye slowly getting worse over time. Their symptoms will stabilise when the shape of their cornea stops changing, which usually happens around twenty years later. A person’s eyesight will often be unaffected in the very early stages of keratoconus, although it may be slightly blurred and distorted. But as the condition progresses, their sight may become more distorted due to further bulging of their cornea. This will eventually lead to further short-sightedness and astigmatism – and so they will often need frequent changes to their spectacle or contact lens prescription to correct this. They may also have increased sensitivity to glare and might see halos around bright lights, which can affect their ability to drive at night. When the condition is more advanced, a person may have scarring of their cornea that can affect their ability to focus. Keratoconus can affect each eye differently. A person may initially only be affected in one eye but eventually, both of their corneas will develop the condition – although this may not be with the same severity.

An optician or ophthalmologist (hospital eye doctor) may perform several different tests to diagnose keratoconus. These include reading charts to check how well the eyes are focusing, as well as scans to measure the thickness and shape of the cornea. As the condition usually takes several months or years to develop, a person will usually be invited for repeat assessments to monitor any changes to the cornea over time.

When keratoconus is in its early stages, a person’s eyesight can usually be corrected with spectacles or soft contact lenses. But when the condition becomes more advanced, rigid gas permeable contact lenses are usually required to correct their sight more adequately. Most people with keratoconus can achieve good sight wearing contact lenses. But in a few severe cases, a person may need a corneal transplant to correct their sight. This involves surgery to remove all or part of a damaged cornea and replace it with healthy tissue from a donor. Even after a corneal transplant, a person may still need to wear spectacles or contact lenses to correct their sight. Newer treatments are becoming available that aim to stop the condition from getting worse. One of these is called ‘collagen cross-linking’, which involves removing a small area of the surface of the cornea, applying drops of vitamin B2 (riboflavin) followed by a burst of ultraviolet-A (UV-A) light. This is thought to cause tiny fibres in the cornea to join together, making it stronger. Another option is corneal implants – flexible plastic rings that are inserted into the edges of the cornea to try and flatten its shape.

Leber congenital amaurosis (LCA) is the term used for a group of inherited eye conditions that cause blindness or severe vision loss in early childhood. It is one of the most common causes of blindness in children, affecting around two or three of every 100,000 newborns. LCA mainly affects the retina, which is the specialised light-sensitive layer that lines the back of the eye. It affects the light-sensing cells called photoreceptors which play a vital role in making eyesight possible by converting light into electrical signals that are transmitted to the brain. When these cells stop working properly or are lost, this leads to sight loss. There are several different types of LCA, which are distinguished by their genetic cause, patterns of sight loss and related eye abnormalities. Some people will experience little change to their sight over time, but the symptoms will gradually worsen for others.

Scientists have so far identified at least 27 different genes that cause LCA. Faults in these genes account for about 80 to 90 per cent of cases of LCA – and so it is likely that more are yet to be identified. The most commonly affected genes are CEP290, CRB1, GUCY2D and RPE65. Each of the genes associated with LCA provides the instructions for making various proteins that play important roles in the healthy development and functioning of the retina, at the back of the eye. For instance, some are essential for the correct development of photoreceptor cells while others are involved in converting light into electrical signals. Faults in these genes disrupt the smooth working of the retina, resulting in sight loss.

Babies affected with LCA are usually born with very poor sight. Within their first few months, parents will often notice they aren’t responding to visual cues and also have involuntary eye movements (known as nystagmus). Often a child will habitually poke, press and rub their eyes with a knuckle or finger, which may contribute to their eyes looking sunken or deep-set. Less commonly, a child may have a range of other sight symptoms, which include keratoconus (an abnormal shape to their cornea at the front of the eye), cataracts (clouding of the lens of the eyes), an aversion to light (photophobia), crossed eyes (strabismus), enophthalmos (the eyeballs are dislocated backwards), extreme farsightedness, and pupils that don’t react normally to light. As the retina breaks down over time, this can also lead to abnormal changes to the pigment at the back of their eye. In rare cases, a child may have symptoms affecting other parts of the body including kidney disease, hearing loss, intellectual disability and/or development delay – although this may indicate that they have a related syndrome rather than LCA.

A test known as electroretinography (ERG) can help doctors to assess how well a child’s retina is working. Infants with LCA will have abnormally low or no electrical activity due to problems with their photoreceptors. Genetic testing can help to confirm a diagnosis of LCA. This can also provide information about the inheritance pattern of the condition and risks to other family members.

Unfortunately, there is currently no cure for LCA. However, the development of gene replacement therapies and other potential new treatments are offering hope for patients. It is important to note that these are gene specific. In 2017, the gene therapy voretigene neparvovec (brand name Luxturna) was approved by the US Food and Drug Administration (FDA) to treat sight loss caused by faults in the RPE65 gene. Luxturna aims to deliver healthy copies of the RPE65 gene into the patient’s retinal cells, restoring the levels of an enzyme needed for the healthy functioning of photoreceptor cells. The results of clinical trials have demonstrated that the treatment can prevent further sight loss and restore some functional vision in patients with LCA. In November 2018, the European Medicines Agency (EMA) approved Luxturna, making it the first and only gene therapy available in Europe to treat inherited retinal disease. In the UK, there are now ongoing discussions at a national level to determine pricing and access to treatment before it can be made available for patients with this type of LCA.

Leber hereditary optic neuropathy is an inherited condition that affects the specialised cable that sends visual information from eye to brain (the optic nerve). It causes sight loss in the centre of the field of vision. Most people with Leber hereditary optic neuropathy are young adult men.

Leber hereditary optic neuropathy is a genetic disorder. So far, 4 genes have been linked to the condition. The affected gene is passed on from mothers to their sons and daughters. It causes a problem with the ‘power-houses’ inside cells (mitochondria) and the optic nerve wastes away. Some people may develop Leber hereditary optic neuropathy even when there is no family history of the condition. This is because people can carry a faulty gene without ever getting symptoms.

Symptoms usually appear by age 30 (from the teens onwards), but can begin later in life or in young childhood. The first signs may be slightly blurred vision or trouble seeing colours in one eye. Symptoms usually appear in the other eye a few weeks or months later. Severe sight loss in both eyes can develop quickly, in just 3 or 4 months, but may take a couple of years. Women are much less likely to be affected, even if they have a genetic fault linked to the condition. Tobacco and alcohol may make symptoms worse.

There is currently no cure for Leber hereditary optic neuropathy.

The retina is the light-sensitive layer of cells that lines the back of the eye. At its centre is an area called the macula. It’s the part of the retina that’s most densely packed with ‘photoreceptor’ cells. We use the macula for seeing in colour and fine detail. A macular hole is a small break or tear in the macula.

The middle of the eye is filled with a clear jelly called vitreous humour. As we age, the jelly starts to pull away from the retina and sometimes it will take some of the macula with it, leaving a macular hole. We don’t know exactly why macular holes develop, but some things make it more likely. Older age, being female and being very short-sighted all affect the chances.

Symptoms of macular hole include central vision becoming blurred or distorted. It may become difficult to read or see well enough to drive. Objects may seem to be smaller than they should be. Eventually a dark spot may develop at the centre of your field of view. Macular hole usually only affects one eye at a time.

Options for treating macular hole depend on whether the hole is still in the early stages, how big it is how it happened. Sometimes, an eye injection with the drug Ocriplasmin can help stop the vitreous jelly from pulling at the retina. If this doesn’t work or if the hole is at a later stage, then keyhole surgery can help close the hole in the macula. Surgery involves removing the vitreous gel and injecting a gas bubble into its place. The gas expands and presses the macula back down so that it can heal in place. The surgery sometimes involves peeling away a very thin membrane that sits on top of the retina. Once the gas bubble has disappeared, if the macular hole has closed vision can continue to slowly improve over time but is unlikely to ever be as good as before the hole.

Meesmann corneal dystrophy is a rare form of corneal dystrophy. It affects the outer layer of the cornea – the clear surface on the front of the eye. It does not usually cause blindness.

Meesmann corneal dystrophy is caused by genetic faults either in the gene K3 or the gene K12. These genes produce a protein called keratin, which helps make up the structure of the outer layer of the cornea (called the epithelium).

People with Meesmann corneal dystrophy have small cysts (sacs that contain fluid) in the outer layer of the cornea. The cysts can appear in children as young as one, but symptoms don’t usually begin until the teens or early adulthood. Symptoms happen when the cysts rupture (burst). They include being sensitive to light, eye irritation or feeling as though there is something in the eye and having watery eyes. Some people may not be able to tolerate wearing contact lenses. People may also have blurred vision from time to time.

Meesmann corneal dystrophy does not always need treatment other than lubrication. Therapeutic contact lenses may help people with stronger symptoms.

Nystagmus is a condition in which people have involuntary eye movement. The eyes usually move from side to side. Most people with nystagmus have trouble with vision. It can affect one or both eyes. There are several different types of nystagmus. Babies may be born with nystagmus or develop it early in childhood. This is known as infantile nystagmus and may have been passed down through the family. Nystagmus can also appear later in life as a result of illness, injury, recreational drugs or alcohol use. This is known as acquired nystagmus.

Nystagmus can happen because of problems with the balance system in the inner ear. The balance system usually tells the eye muscles how to move so that our eyes can keep looking at the same place when we turn our head. Nystagmus in early childhood may be due to a faulty gene passed through the family. It can also be linked to conditions such as Down syndrome, albinism, brain disorders and other eye conditions such as cataract or retinal disorders. In some children however, the cause is unknown. When nystagmus appears later in life it can be due to another condition, such as a stroke or multiple sclerosis. Nystagmus can be the first sign of serious disorder of the eye or brain.

Nystagmus causes an involuntary, wobbly movement of the eyes, usually from side to side. Vision can be close to normal or be seriously reduced. It can make it hard to judge depth. People with nystagmus may become tired easily, due to the effort needed to look at things. It can make it harder to drive, work and study.

Treatment options for nystagmus are limited. Glasses or contact lenses may improve sight but will not correct nystagmus. Sometimes medication can reduce the nystagmus and improve vision. In some cases, surgery may be used to cut and reattach some of the eye muscles. The aim is to correct for abnormal head turns and/or to slow the involuntary movements and improve vision.

Ocular mucous membrane pemphigoid is a type of scarring conjunctivitis. It affects the membrane that lines the eyelids and covers the white of the eye (the conjunctiva). In the UK, around 1 in a million people have ocular mucous membrane pemphigoid. If it’s not treated, it can lead to blindness.

We don’t know exactly what causes ‘ocular pemphigoid’. It’s an auto-immune condition, which means that the body’s defence against infection (the immune system) has turned on its own body. Most people with the condition are between the ages of 60-80, but it can start in early childhood on rare occasions.

Pemphigoid is the name for a group of rare conditions that cause blisters and scarring on the skin. The ocular (eye) mucous membrane form is often part of a wider condition that affects other membranes that line the body, such as in the mouth, nose, throat and genitals.

Current treatment for ocular mucous membrane pemphigoid usually aims to reduce inflammation, with steroids and other anti-inflammatory drugs. Surgery can’t cure the condition but can sometime help to ease symptoms. For example, surgery can ease the position of a scarred eyelid that is pulling the eyelashes inwards and corneal transplant can restore sight lost to scarring.

Proliferative vitreoretinopathy is a condition that can develop as a complication of a detached retina. The retina is the light-sensitive layer of tissue lining the back of the eye. Having a detached retina means that it has come away from the supporting tissue underneath it. This can happen when fluid builds-up under the retina after coming from the compartment of the eye that's in front of the retina through a hole or tear. In proliferative vitreoretinopathy, some of the cells in the retina start to multiply and may produce scar tissue. The scar tightens and pulls the retina away again. If this happens, it is not possible to reattach without sight loss.

Proliferative vitreoretinopathy happens when cells in the retinal pigment epithelium (one of the different layers that make up the retina) come into contact with fluid from the vitreous humour – a clear gel that fills the space in front of the retina. The contact triggers an immune system response that tells the cells to start multiplying.

If proliferative vitreoretinopathy leads to scar tissue, the scar will block light from reaching parts of the retina. This will mean there are some patches of sight loss in the affected eye. Because it's a complication that can follow surgery to re-attach a detached retina, the medical team will monitor your recovery to find out whether it is likely to develop.

A second operation to re-attach the retina is the only treatment for proliferative vitreoretinopathy but there will be sight loss in the area of retina affected by scar tissue.

Pterygium is a benign growth from the lining of the eyelid (the conjunctiva) onto the clear front surface of the eye (the cornea). It can distort or cover the cornea and significantly reduce sight. Pterygium is also known as surfer’s eye. It’s a common cause of sight loss in one or both eyes in many parts of the world.

Being exposed to ultraviolet light, for example from sunlight, is thought to be the main trigger for pterygium. But genetics may play an important part too, as some people seem to be more at risk than others

Some people with pterygium will not have symptoms. But the eye can become red and swollen (inflamed) and may feel irritated. As pterygium grows, it can change the curve of the cornea (astigmatism). This can make vision blurred and lead to eye strain. It may get in the way of your line of sight. Pterygium is wing-shaped. Many people say they don’t like the way it makes them look.

At the moment the only treatment for pterygium is to surgically remove it. Steroid drops can help treat inflammation but they don’t affect the growth itself.

Refractive error refers to a range of common conditions, including short-sightedness and long-sightedness, that mean light isn’t focusing correctly when it hits the retina – the light-sensitive layer at the back of the eye. This can cause vision to become blurred (out of focus). Refractive errors are very common and affect millions of children and adults in the UK. A lot of the time it only causes mild eyestrain or the inconvenience of having to wear glasses or contact lenses. But for some people the impact is much more severe. Severe short-sightedness (high myopia) is associated with an increased risk of retinal degeneration (myopic maculopathy) or retinal detachment – a medical emergency that requires urgent treatment. And uncorrected refractive error can be damaging in children whose eyesight is still developing. This is why funding vital research into refractive error plays a big part in our mission to create a future everyone can see.

Refractive error is mainly associated with small variations in the shape of the eye. These variations aren’t really noticeable without close-up examination - but they are significant enough to affect how light is focused on the retina as it passes through the eye. The retina is responsible for converting light into signals carried along the optic nerve to the brain, enabling us to process vision. But for vision to be processed clearly, light needs to be focused accurately. Family history is the biggest risk factor for refractive error. Developmental factors may also play a role (for example, being born prematurely may increase the risk) and having other eye conditions can make refractive error more likely. The four most common types of refractive error are: **Short-sightedness** Short-sight occurs when light focuses just short of the retina, because the front of the eye is too curved or the eyeball is too long. Distant objects become blurred, while more close-up things can be seen more clearly. This often runs in families and is also more common in people with Far Eastern heritage. Research suggests too much close-up working can cause short-sightedness, and it often develops or get worse during teenage years. Not spending enough time outdoors is another important risk factor during childhood. Myopia can develop in later life too, including as a result of other eye conditions, such as cataract. **Long-sightedness** Long-sight means light is focusing too far beyond the retina, because the front of the eye isn’t curved enough or the eyeball is slightly short. As a result, close-up objects become blurry, while far-away things can be seen more clearly. Long-sight often runs in families too and tends to be more common in people with European heritage. Babies are often born with some degree of long-sight but grow out of it by around age two as their eyes develop. If they don’t, there’s an increased risk of developing a squint or ‘lazy eye’ (amblyopia). Many people with the condition find their eyes are able to adapt by focusing harder while they are young, but in adulthood, particularly beyond 40. **Presbyopia** This is similar to long-sightedness but occurs as a result of ageing. Our lenses become less flexible as we age, which makes focusing harder. Reading glasses or contact lenses are needed by almost all of us after the age of 40-50. **Astigmatism** This happens because the front of the eye is not evenly curved – a bit like a rugby ball compared to a football. As a result, as light passes through the eye, there’ll be more than one focus point on the retina, which means certain areas of a person’s field of vision will become blurry. As with long-sightedness, astigmatism is very common at birth but often corrects itself as the eye develops. If by around age two this hasn’t happened, problems can occur. Astigmatism can develop in adulthood too, particularly after an eye injury or surgery, and it often occurs alongside short or long-sightedness, rather than on its own.

Symptoms can vary depending on which type of refractive error somebody has and how severe it is. For some people symptoms are very mild and only noticeable during tasks that require a lot of focusing, such as reading, using a computer or driving. For others vision can be severely affected. These are the signs and symptoms typically associated with refractive error: - Blurred vision. This may affect distant or close-up objects, or even both. Headaches. Having to try harder to focus and adjust the eyes often causes headaches. - Tired, strained eyes. This can happen with tasks that involve lots of focusing. Squinting. This can be a sign somebody’s having to work harder than normal to focus their vision (note that this is different from an ‘eye turn’, also known as a squint).

Refractive error is generally diagnosed during routine eye tests. These will look at any difficulty or changes with focusing on both near and distant objects, to determine whether somebody is short or long-sighted. Eye tests will also look at how well your eyes are working together and how they react to light. It’s recommended that everybody has a routine eye test every two years, although those known to be at higher risk may be eligible for more frequent free tests. Children often aren’t aware if there’s a problem with their vision as they may never have known any different. So it’s important to look out for possible signs that they’re struggling to see clearly – such as sitting very close to the television, squinting, and rubbing their eyes a lot. The sooner problems are detected, the better, so it’s always best to get things checked out.

Most of the time refractive error is managed by wearing glasses or contact lenses. These will help correct blurred vision and may be required all the time or just while carrying out certain tasks, like reading and driving. Some people find their vision worsens as they get older and they may need stronger prescriptions. For refractive error associated with ageing, reading glasses can help. If refractive error is very mild, treatment may not always be required, as the eyes may be able to adjust. However, having to work too hard to focus can result in eye strain and headaches, so glasses may still be required even if the impact on vision seems small. It’s very important that young children receive appropriate treatment, as not treating refractive errors while their eyes and brains are still developing may lead to further problems down the line. This is because in order for their brains to ‘learn’ how to see correctly, both eyes need to be working clearly and equally. Treatment for children is usually glasses. For adults with more severe refractive error, laser eye surgery to correct the shape of the cornea (front of the eye) may be an option. However, this isn’t suitable for everybody and will generally need to be paid for privately. Short-sight is sometimes also treated with surgery to replace the lens with an artificial one - a relatively new procedure that can be very effective but isn’t always suitable.

The retina is the light-sensitive tissue lining the back of the inside of the eye. It’s made up of different layers, including the light-sensing cells known as photoreceptors that are essential for sight. A layer of underlying supporting tissue contains blood vessels that supply the photoreceptors with the food and oxygen they need to stay healthy. The layers of the retina need to stay in place to stay healthy and working correctly. A retinal detachment is when the layer of photoreceptors begins to pull away from the supporting tissue underneath it. A detached retina can cause permanent sight loss in the affected eye if it isn’t detected and repaired with surgery quickly. A retinal detachment needs urgent assessment by a specialist eye surgeon. The condition is rare, affecting around one in 10,000 people each year in the UK.

The main cause of a retinal detachment is when a tear or break in the retina allows fluid from the middle part of the eye, the vitreous cavity, to leak through and get underneath it - resulting in retinal detachment.This most commonly occurs when, as a result of ageing the watery vitreous gel in the eye separates from the retina - typically in the 50-70 year-old age group. It is more common in short sighted patients. Occasionally either before or after surgery to repair detached retinas scar tissue can form on the retinal surface. This scar tissue can contract and pull at the retina, preventing successful reattachment or occasionally causing the retina to redetach after after successful repair. An eye injury, or blow to the head or some other medical conditions that affect the retina may also lead to a retinal detachment. Anyone can develop a retinal detachment at any time, but it is most common in those over the age of 40 – and very rare in children under 16. People who are very short-sighted, have had eye surgery in the past, or who have a family history of retinal detachment are at an increased risk of developing the condition. If someone has experienced a detached retina in one eye, they also have a higher chance of it happening in their other eye.

The symptoms of a retinal detachment can either happen very suddenly or else may come on more gradually. A person may notice that their sight becomes blurred – or a dramatic change to the number or type of floaters (the tiny specks and spots that seem to float across a person’s visual field) in their eye. Other signs are starting to see flashes of light around the edges of their vision, or a dark ‘curtain-like’ shadow descending from the top of their eye or across from the side. If a person is experiencing any of these symptoms, they should see an eye health professional (such as an optician or hospital eye doctor) within 24 hours. Although these symptoms don’t always mean they have a retinal detachment, it’s really important to have an eye examination to check.

An eye health professional will usually examine the back of a person’s eyes using a bright light and a special lens – to look for any holes, tears or detachments to the retina. They may also carry out imaging tests to look more closely at the layers of retinal tissue for any signs of damage.

A retinal detachment can be treated with surgery to re-attach the photoreceptor layer to the underlying support tissue. In general, the sooner an operation can be carried out, this increases the chances of a good outcome. There are different types of surgical approaches for retinal detachment and the most appropriate option will be very individual to each person. A hospital eye doctor will examine their eye and decide how quickly surgery needs to happen – this may be within 24 hours or a few days. Surgery is successful at reattaching the retina in about 80-90% of cases with the first operation, but how well a person’s sight recovers will depend on a number of factors such as the location, cause, and extent of the detachment, and if they have any other complicating factors such as other eye conditions. But if a retinal detachment is left untreated, a person is likely to eventually lose all sight in their affected eye. If a person has a tear or hole in their retina that hasn’t yet led to a detachment, they may be offered laser surgery or cryotherapy (a procedure involving a freezing probe) to help prevent this from happening. These treatments aim to weld the retina firmly to the underlying support tissue and seal the damaged area to prevent fluid passing through that may cause a detachment.

Retinitis pigmentosa is the term used for a group of closely related inherited eye conditions that affect the retina, the specialised light-sensitive tissue at the back of the eye. A person’s sight loss usually happens gradually, over many years – and sometimes eventually leads to registered blindness. Retinis pigmentosa is the most common inherited eye condition, affecting around one in 4,000 people in the UK. Although most people with the condition will only have sight loss, less commonly it can occur as part of a broader inherited syndrome that affects other parts of the body. Examples include Usher, Bardet-Biedl (BBS) and Alström syndromes and Refsum disease, which all cause RP-like sight loss along with other health conditions.

Retinitis pigmentosa is caused by the gradual decline and loss of light-sensing cells called photoreceptors in the retina, which are vital for healthy eyesight. Scientists have so far identified that faults in more than 60 different genes can cause RP – but there are many more still to discover. Examples include genes known as RHO, USH2A and RPCR. These are passed down through families in different patterns, which can skip a generation depending on the exact genetic cause. Scientists are studying the function of the genes responsible for retinitis pigmentosa to find out more about the biology behind the condition and uncover potential new treatment strategies. Faults in any of these genes cause photoreceptors to stop working and die over time, leading to sight loss in patients. They each contain the instructions for making proteins that are important for maintaining the correct structure and function of these important retinal cells.

Symptoms of retinitis pigmentosa tend to appear during childhood or early adulthood – but in rare cases they can start much later. However, it is difficult to predict both the severity and how quickly an individual’s sight loss will progress – as this varies widely from person to person depending on the exact genetic cause of their condition. One of the earliest symptoms of RP is ‘night blindness’ which can affect a person’s ability to see in dim light. They will often start to have problems with their side (or peripheral) sight, which may cause them to start bumping into things like doors or furniture. As the condition progresses, they will gradually develop ‘tunnel vision’ – but many people will keep their detailed, straight-ahead (central) sight into their 50s or older. However, people with advanced stages of retinitis pigmentosa will often also develop problems with their central vision and this can severely affect their ability to carry out everyday activities like reading. They may also find it more challenging to deal with glare from bright lights and sunlight and in adapting to changes in light levels. Some people will eventually develop complete blindness.

An optometrist or ophthalmologist (hospital eye doctor) will use a special instrument to examine a person’s retina to look for the presence of abnormal patches of dark pigment, which is a common sign of retinitis pigmentosa. Further detailed imaging tests will enable them to look at the fine structure of the retina for more subtle signs of damage. They will usually also carry out a field of vision test to assess if a person has any changes to their peripheral sight. They may also perform a test known as electroretinogram (ERG) to measure the electrical activity of the retina, which is usually decreased in patients with retinitis pigmentosa due to the decline of their photoreceptor cells. Genetic testing can help to confirm a diagnosis of retinitis pigmentosa. This can also provide information about the inheritance pattern of the condition and risks to other family members.

Unfortunately, there is currently no known cure or effective treatments that can stop the progression of retinitis pigmentosa. However, the development of gene replacement therapies and other potential new treatments are offering hope for patients for the future. Some people with retinitis pigmentosa will develop cataracts – and in these cases, cataract surgery may help improve their sight.

Retinoblastoma is a rare type of eye cancer which affects the retina, the light sensitive layer of the eye. This type of cancer mainly affects young children under the age of five. One in 2000 children in the UK are affected by this condition with approximately 40-50 new cases being diagnosed each year. In 40% of cases the cancer can lead to the loss of one eye. However, in over 95% of cases the cancer is treated successfully. Retinoblastoma can occur as an inherited and non-inherited condition, which can affect one or both eyes.

RB1 is the gene that is primarily associated with retinoblastoma. This gene regulates cell growth and stops uncontrollable cell division. If there is a change or mutation in this gene it can result in a change in a protein, which changes the way the protein functions and results in a tumour. In the majority of cases of hereditary retinoblastoma there is a change in 1 of the 2 copies of the RB1 gene. This change is inherited from one parent. If there is another mutation in the second copy of the gene this can lead to the development of retinoblastoma. Non-hereditary retinoblastoma usually affects one eye. Children with this type of retinoblastoma are born with two normal copies of the RB1 gene. However, both copies of the RB1 gene then acquire changes or mutations that result in a defective protein being produced, which causes retinoblastoma. These changes in the gene only affect the eye and cannot be passed down to the next generation.

Symptoms may be related to other less serious conditions so it is important to have your child’s eyes tested if you have any concerns. The symptoms to be aware of includes: - An unusual white reflection in the pupil – this may occur in photos where only the healthy eyes appears red from the flash. - A white colour in the centre of the eye (pupil) when light shone in the eye, such as when taking a flash photograph - Squint – eyes that look in different directions - Change in the colour of the iris - Poor vision – Your child may express that they cannot focus on faces or objects. They may not be able to see as well as they used to - Red or inflamed eye It’s important to detect these symptoms early to help ensure a successful outcome for the child.

A red reflex test will be carried out by your GP. This test will take place in a darkened room using a magnifying instrument with a light at one end. The light will be shone into your child’s eyes in order to see if there is a red reflection, which is normal. If a white reflection is seen, your GP will refer your child to an ophthalmologist who will perform another test to examine further. Once referred, the ophthalmologist may repeat the red reflex test using eye drops to allow a clearer view of the retina. Another method of diagnosis is the use of an ultrasound scan. Prior to the scan gel is rubbed on the outside of the eyelid and a small ultrasound probe, which scans the eye, is placed on the outside of the eyelid.

The method of treatment will be determined by a medical professional. It will be dependent on the stage at which the cancer has been detected, the severity and other influential factors. Treatment is successful in treating retinoblastoma in more than 95% of cases. However, in 40% of cases the cancer can lead to loss of one eye, which is why Fight for Sight is investing in research to help develop new treatments that will help save children’s sight. Treatments include: **Cryotherapy** A technique used to freeze small tumours. This treatment may be needed more than once. It is performed under general anaesthetic so your child will not feel any pain during the procedure. **Chemotherapy** Chemotherapy may be required for larger sized tumours as it may be needed to shrink down the size of the initial tumour. However it may also be used for small tumours. It can be given to the whole body (systemic), to the eye via a blood vessel (intra-arterial) or injected into the eye (intravitreal). Systemic chemotherapy may also be used after the cancerous eye has been removed, in case there are still signs of the cancer in the surrounding areas. **Enucleation** If the tumour is extremely large and there is no sight from the eye, it may be recommended for your child to have surgery to remove the eye. If enucleation occurs, an artificial eye will be given and fitted. **Photocoagulation** Photocoagulation involves the use of a laser beam to destroy the tumour itself. This treatment is used for small tumours which are located towards the back of the eye. This treatment can be used in combination with chemotherapy **Radiotherapy** Radiotherapy uses high energy x- rays or particles are used to kill the cancer cells. There are two main types of radiotherapy which includes external beam radiation therapy and brachytherapy. External beam radiation therapy (EBRT) is the use of a machine to directly aim beams of radiation at the cancer. Whilst brachytherapy (also known as plaque radiotherapy) is the use of small pieces of radioactive metals which are placed near the site of the cancer which are able to kill the cancer cells.

Retinopathy of prematurity is a condition that can affect babies who are born early, before the blood vessels that supply the light-sensitive layer of the eye (the retina) have finished growing. In this condition, the retinal blood vessels grow in a disorganised way after the baby is born. This can lead to bleeding and scarring that can pull the retina away from the wall of the eye (retinal detachment). If it’s not treated, retinopathy of prematurity can cause irreversible sight loss. It is a leading cause of childhood blindness worldwide.

Premature babies that have a low birth weight (less than 1500g) or are born at 32 weeks or less, are most at risk of retinopathy of prematurity. The lower the birth weight, the bigger the risk. High levels of oxygen necessary to support premature babies can also increase risk of retinopathy of prematurity.

Retinopathy of prematurity is classed into five stages. These range from very mild to very severe. Most babies will have stage 1 or stage 2 and will go on to have normal vision. The more severe stages can lead to severe sight impairment. • Stage one: Blood vessel growth is mildly abnormal. Babies usually recover without any medical treatment. • Stage two: Blood vessel growth is moderately abnormal. Babies usually recover without any medical treatment in this stage as well. • Stage three: Blood vessel growth is severely abnormal. Treatment may be required at this stage. • Stage four: Partial retinal detachment occurs which means the retina is pulling away from the back of the eye. • Stage five: Retinal detachment occurs, which means the retina has fully detached from the back of the eye. This leads to permanent loss of vision.

Retinopathy of prematurity is diagnosed by a screening eye examination given to all premature babies at risk of the condition. It is done by an ophthalmologist or other specially trained health professional, using an ophthalmoscope or a camera. Some babies will not require any treatment as the issue will resolve itself. However, if treatment is required then it is usually treated by laser therapy or freezing treatment (cryotherapy). Both treatments target specific parts of the retina to stop the growth of abnormal blood vessels. Some cases are now treated with injections, which is used alongside laser therapy, to aid in stopping the growth of abnormal blood vessels. Early treatment is very successful at preventing severe sight loss in most cases.

Stargardt macular dystrophy (or Stargardt disease) is a genetic eye condition that causes progressive central sight loss. Affecting a person’s fine detailed vision, the condition is estimated to affect between one in 8,000 to 10,000 people in the UK. Stargardt disease is a consequence of progressive damage to the macula, which is a small area in the centre of the retina, the specialised light-sensitive layer that lines the back of the eye. The macula is responsible for our sharp, straight-ahead vision that we rely on for many activities – such as reading, recognising faces or watching TV. Once the condition develops, a person’s symptoms will get slowly worse over time. As they will usually maintain their peripheral (side) vision, it is rare for someone to become completely blind. However, most people with Stargardt disease will experience severe sight loss that affects their daily lives.

Stargardt disease is caused by faults in a gene known as ABCA4. This gene provides the instructions for making an important protein that usually removes toxic by-products out of the light-sensing cells in the retina, at the back of the eye.. But when this protein is missing or faulty, these substances build up and form a fatty waste product – called lipofuscin – in and around the macula that start to affect the person’s central vision. And eventually this causes the progressive sight loss that is characteristic of Stargardt disease. When faults in the ABCA4 gene are the cause of the condition, a child will inherit one faulty copy of the gene from each parent. Their parents will typically each carry one copy of the faulty gene but will not have the disease themselves. Although having faults in ABCA4 is the most common cause of Stargardt disease, a minority of patients have faults in other genes – ELOVL4, PROM1 and RDS (also known as PRPH2).

The signs and symptoms of Stargardt disease typically start in late childhood or adolescence and will gradually get worse over time. However, the age that the first symptoms develop, and the speed of the disease progression varies widely from person to person. For some people, sight loss may not begin until later in adulthood. At first a person will usually experience unclear or blurry vision. As their condition progresses, things may start to appear distorted or wavy and some people may also develop blind spots. In addition to problems affecting their central vision, sometimes a person may experience problems with light, such as sensitivity and difficulties adapting to low light levels - and some may have issues with colour perception. As Stargardt disease doesn’t normally affect other parts of the retina outside of the macula, a person will usually maintain their side vision and won’t become completely blind.

A loss or change in central vision will usually lead to a person being diagnosed with Stargardt disease. An ophthalmologist (hospital eye doctor) will examine the retina at the back of the eye to look for characteristic yellowish flecks – lipofuscin deposits – positioned in and around their macula, which can help them to diagnose the condition. These can vary widely in their size, number, colour and appearance. But as the disease progresses, the flecks usually extend outward from the macula in a ring-like pattern. A person may also be asked to read standard eye charts as well as other tests to assess sight loss, such as: - visual field testing – to check their central and side vision - colour testing – to detect any loss of colour vision - fundus photo – to look at their retina in detail - electroretinography (ERG) – to test their retinal function - optical coherence tomography (OCT) – to look for structural abnormalities in the layers of their retina - Genetic testing is also available to help identify the genes involved in a person’s Stargardt disease and provide information about the inheritance pattern and risks to other family members.

Unfortunately, there is currently no cure for Stargardt disease – and very little can be done to slow down its progression. However, there is a lot of ongoing research into potential new treatments – including gene, stem and drug therapies. Wearing protective sunglasses outdoors may help to protect vision by reducing exposure to ultraviolet (UV) light which can potentially cause further retinal damage. Some evidence suggests that people with the condition should avoid taking vitamin A supplements as this may help promote the accumulation of lipofuscin.

Thyroid eye disease (TED) is a condition in which parts of the eye and eye socket become inflamed and swell. It’s an ‘autoimmune’ disorder, which means that the body uses its natural defences against its own cells. Around 300,000 people in the UK have TED. It is also known as Graves orbitopathy or Graves ophthalmopathy.

We don’t fully understand what causes TED. But we do know that the body’s immune system triggers a chain of events that leads to swelling and scarring around the eye socket as well as an increase in the amount of tissue. TED is most likely to affect people with an over-active thyroid gland.

The most common symptoms of TED are redness and discomfort. Swelling of the fat and muscle behind the eye can push the eyes forward (known as proptosis). This may prevent the eyelids completely meeting when blinking or closing the eyes (‘lagopthalmos’). Eyelids may open too far (eyelid retraction) exposing the clear, sensitive window of the eye (the cornea) to damage. The cornea may become dry and uncomfortable. In addition, the inner lining of the eyelid (the conjunctiva) can become inflamed (conjunctivitis), or swell (chemosis). In some people, eye movements are reduced and this can cause double vision. In extreme cases the optic nerve (which is the cable connecting the eye and the brain) is squeezed. This could potentially cause sight loss.

In many cases, the swelling and inflammation may get better on their own but a doctor may suggest lubricating eye drops or nutrition supplements to help while this happens. Abnormal thyroid gland activity needs to be treated as uncontrolled activity could drive the changes in TED. Smoking is a risk factor that is known to make TED much worse. Smokers should stop (or at least drastically cut down). GPs can provide support with this. If the swelling and inflammation is moderate or severe then a doctor may suggest therapy with steroids. Other ways to tackle inflammation include treatment with x-rays (radiotherapy) or newer drugs such as Rituximab. When the inflammation has settled, surgery may be an option. The aim is to help the eyes move back into their sockets and take pressure off the optic nerve. Decompression surgery is sometimes done in an emergency if there is a threat to sight. Surgery to improve double vision (squint surgery) and to repair the eyelids may also be needed.

Trachoma is an infectious eye condition. The infection usually begins in early childhood and often leads to the eyelashes turning inwards (trichiasis). Sight loss from trachoma happens over time. When the eyelashes turn in, they scratch the cornea (the clear front surface of the eye). Eventually, the cornea becomes too scratched for light to pass through. It’s a major cause of blindness in many developing countries.

Trachoma is triggered by repeat infection with bacteria known as Chlamydia trachomatis. The infection makes the lining of the eyelid (the conjunctiva) become inflamed. The infection itself can be treated with antibiotics, but the inflammation can last long after the bacteria are gone. Long-term (chronic) inflammation makes the conjunctiva scarred and tight. This is what pulls the eyelashes inwards.

The first symptoms of infection include discharge from the eyes, redness and irritated eyes. Later on, the eyes get inflamed and scar. It’s painful when the eyelashes rub the cornea.

The infection causing trachoma can be cured with antibiotics, but the condition often continues and gets worse because of repeated infection and long-term inflammation. Eyelid surgery can be done to correct the lashes that have turned inwards. The aim is to prevent pain and sight loss, but it doesn’t always work as the inflammation may still continue.

Uveal melanoma is a type of eye cancer. It affects about 6 people per million. Those with pale skin and blue or grey eyes are the most at risk.

In uveal melanoma, tumours begin in the cells that give eyes their colour (these cells are called ‘melanocytes’). There is not usually any family history of the condition, and the exact cause in still unknown.

Symptoms of uveal melanoma depend on exactly where the tumour is within the middle layer of the eye (the uvea). They may include blurred vision, seeing flashes of light, floaters, a change in eye colour and changes to how much of the world you can see (the field of vision). Uveal melanoma is most likely to be spotted at a routine eye exam.

The main aim of treating uveal melanoma is to keep vision where possible and, if not, to prevent the eye becoming painful, and stop the cancer from spreading beyond the eye. Treatments for uveal melanoma include radiotherapy and surgery. Both options can mean that the eye can be preserved and the local tumour growth can be controlled. However, there may be some sight loss as a side-effect of treatment. In some cases, surgery to remove the whole eye may be the best option, for example if the tumour is very large or if the patient would rather have it done. Unfortunately, in around half of people with this type of cancer, tumour cells will escape into the blood stream and spread from the eye to the liver. If so, it is almost always fatal.

Uveitis is the name for inflammation within the eye. Uveitis is a major cause of blindness.

Some types of uveitis are caused by an infection such as the herpes virus or a bacterial infection. The body tries to fight off infection using the immune system, but sometimes the immune system can also be damaging. In such cases, white blood cells can enter the eye and cause inflammation that damages delicate eye tissue. Uveitis may be due to a condition that also affects other parts of the body, such as multiple sclerosis, inflammatory bowel disease or some types of arthritis. Non-infectious uveitis can be an 'auto-immune' condition, which means the body attacks itself. Sometimes this can be limited to the eye, such as in Birdshot uveitis.

Symptoms of uveitis can include red eyes, pain, being sensitive to light, blurred vision, floaters and seeing flashing lights. The exact symptoms will depend on the type of uveitis and which part of the eye is affected.

Treatment for non-infectious uveitis is usually with steroids. These can be given as eye drops, tablets or injections around or in the eye. Sometimes other drugs to dampen down the body’s immune system are needed. The treatments may cause side effects that need to be monitored and treated.

Wolfram syndrome is a rare inherited disorder that causes sight loss as well as problems in other parts of the body. It used to be called DIDMOAD, which stands for the main problems of diabetes insipidus, diabetes mellitus, optic atrophy and deafness. Sight loss in Wolfram syndrome is due to damage to the optic nerve (the specialised cable that carries visual signals from the eye to the brain). When the optic nerve is damaged, it becomes pale in colour (optic atrophy). The cells within the optic nerve that are affected in Wolfram syndrome are known as retinal ganglion cells. Vison gets worse as more of them are lost.

There are 2 types of Wolfram syndrome that we know of so far. Wolfram syndrome type 1 (which is much more common) is caused by a fault in the gene WFS1. Wolfram syndrome type 2 is due to a fault in the gene CISD2. We know that these genetic faults affect the ‘endoplasmic reticulum’ – the name for a part inside the cells of the body. It works as a factory to produce proteins. The genetic faults also affect mitochondria – the tiny batteries within our cells that produce energy. As a result, the affected cells have great trouble producing enough energy to survive, but we don’t know exactly how it all happens.

People with Wolfram syndrome start to lose their sight as young children and almost all of them are eventually registered blind. They become aware of losing their central vision, which gradually gets worse, and they also stop being able to discriminate colours and fine contrast.

People with Wolfram syndrome can be treated for hormonal imbalances and for the high blood sugar caused by diabetes. However, there are currently no treatments that can stop sight loss from getting worse in this genetic disorder.