4 min

YOUR COMPLETE GUIDE TO DRY EYES

ALEX IONIDES, OPHTHALMIC SURGEON AT MOORFIELDS EYE HOSPITAL, CO-FOUNDER AT MTHK

What are Dry Eyes?

Dry eyes are a condition that affects the tear film - the three-layer protective covering on the eyes' surface. A smooth and stable tear film is necessary for clear and comfortable vision. Any disruptions to this film can cause dry eyes - with symptoms such as burning, itching, watering, and blurred vision (more below).

Dry eyes are a multifactorial disease, meaning that many different factors can contribute to its development and cause disruptions to the tear film.

As a first step, our 'Online Eye Test' (link below) includes an adapted OSDI (Ocular Surface Disease Index) ophthalmology test. The test takes less than a minute and tells you how dry your eyes are. You get a score from 0 to 100 - the higher the score, the drier your eyes are.

Online Eye Test

“When you blink, you produce tears that wash over the surface of your eyes, forming a thin coating called the tear film. This tear film keeps your eyes healthy and helps you focus properly, giving you clear vision.”

ALEX IONIDES, CONSULTANT OPHTHALMIC SURGEON AT MOORFIELDS EYE HOSPITAL, CO-FOUNDER AT MTHK.

The different types of dry eyes (dry eye disease)

Evaporative Dry Eyes: The majority (over 90%) of dry eye cases are evaporative dry eyes. This occurs when the tears on the eyes’ surface evaporate too quickly. This is typically caused by dysfunction in the meibomian glands, which produce the tear film's outer oily (lipid) layer. When these glands do not function properly, the oily layer becomes unstable - exposing the middle watery (aqueous) layer - leading to dry eyes. This accounts for the majority of dry eye cases.
Aqueous Deficient Dry Eyes: Aqueous deficient dry eye is a condition in which the eyes do not produce enough tears to keep the surface of the eye moist and comfortable. This can happen when the lacrimal gland, located in the upper, outer corner of each eye, is not producing enough of the aqueous (middle) layer of tears. Autoimmune conditions, corneal sensory loss, and obstructions in the lacrimal glands or ducts can all lead to aqueous deficiency. Additionally, certain drugs and hormonal imbalances, including those that occur during menopause, can contribute to aqueous deficient dry eye. Sjögren's Syndrome is an autoimmune disorder that can also cause aqueous deficiency, as well as other symptoms such as dry eyes and mouth.
Mixed Dry Eyes: Lastly, mixed dry eye is characterised by a combination of aqueous tear deficiency and tear film instability, causing dry eye symptoms.

What are the Symptoms of Dry Eyes

Evaporative Dry Eye symptoms & Aqueous Deficient Dry Eye symptoms include:

Stinging, burning, scratchy sensation in your eyes.
Blurred vision or eye fatigue.
Stringy mucus in or around your eyes.
Sensitivity to light.
Eye redness that progresses through the day.
Feeling like there's something (a foreign object) in your eyes.
Difficulty wearing contact lenses.
Difficulty with nighttime driving.
Decreased tolerance for activities requiring sustained visual attention (reading, computer use, etc.)
Watery eyes, with excess tears running down your cheeks.(A counterintuitive symptom that occurs because the eyes are trying to increase tear production.)

Why Does Dry Eye Cause Watery Eyes?

Why do dry eyes water? This seems counterintuitive - but it’s a common question.

When your meibomian glands don’t make enough oils (for the outer lipid layer of the tear film), the middle, watery (aqueous) layer evaporates too quickly. In response, your lacrimal glands (on the upper, outer corner of each eye) try to make more watery tears to compensate. But these tears can’t properly coat your eyes like the oily layer. So, they can’t solve the underlying problem.

Your meibomian glands are the tiny oil glands that line the eyelids’ margin (the edges that touch when the eyelids are closed). These glands secrete oil which coats the surface of our eyes and keeps the water component of our tears from evaporating (drying out).

Eye Drops + Eye Spray

“The 20-20-20 rule. Look away from your screen every 20 minutes, at something 20 feet away, for 20 seconds - this helps to reduce eye strain.”

ALEX IONIDES, CONSULTANT OPHTHALMIC SURGEON AT MOORFIELDS EYE HOSPITAL, CO-FOUNDER AT MTHK.

Managing & preventing Dry Eyes

The 20-20-20 rule: Take periodic eye breaks if you’re reading or doing another task requiring visual concentration. Close your eyes for a few minutes. Or repeatedly blink for a few seconds to help spread your tears evenly over your eyes. Looking away from your computer screen every 20 minutes at something 20 feet away for 20 seconds helps to reduce strain and fatigue on your eye muscles. This is known as the 20-20-20 rule
Diet & Omega-3: Omega-3 fatty acids are found in the lipid (top) layer of your tears - so increasing your dietary intake will strengthen your tear film and help reduce tear evaporation. Choose foods rich in omega-3 and omega-6, such as oily fish, nuts, seeds, eggs and leafy greens.
Know your medication: Certain medications, such as antihistamines, antidepressants, painkillers, and oral contraceptives, can cause Dry Eye. If you’re taking any of these and experiencing dry eye, talk to your GP about your options. [Drops and sprays](https://mthk.com/p/eye-drops-and-spray) can help in the meantime - they moisturise the eye's surface, strengthening the lipid (top) layer - and stabilising the aqueous (middle) layer of your tear film.
Avoid air blowing directly into your eyes: Don’t direct hair dryers, heaters, air conditioners or fans toward your eyes.
Your environment: Your eyes don't like dusty, windy, and smoky environments - they cause your tears to evaporate. Avoid central heating and air conditioning when possible. And use a humidifier to help moisten your eyes. The air at high altitudes, in desert areas and in aeroplanes can be arid. When spending time in such an environment, it may be helpful to frequently close your eyes for a few minutes to minimise your tears’ evaporation.
Add moisture to the air: In winter (or in central heating or air conditioned environments) , use a humidifier to add moisture to the dry air.
Stop smoking / avoid smoke: If you smoke, a quit-smoking strategy will help with dry eyes. If you don’t smoke, stay away from people who do. Smoke can worsen dry eye symptoms.
Keep blinking: Normal blinking happens without thinking, but if you’re spending long hours in front of a screen, you’ll need to take regular breaks to regulate tear production. Your Dry Eye might cause Computer Vision Syndrome (CVS), which can also cause blurred or double vision, headaches, and general eye irritation.
Wraparound glasses & sunglasses: Large, wraparound glasses and sunglasses can help. Also, safety shields can be added to the tops and sides of glasses to block wind and dry air.
Take care with contact lenses: If you wear [contact lenses](https://mthk.com/blog/contact-lenses-dos-donts) and your eyes are dry, you may need to switch to glasses while your eyes recover. We recommend at least a day off every week (if you wear contact lenses daily). Regular eye checks are also a good rule of thumb.
Use eye drops & sprays: If you have chronic dry eyes, use eye [drops & sprays](https://mthk.com/p/eye-drops-and-spray) even when your eyes feel fine to keep them well-lubricated. Make sure the Eye Drops & Sprays are preservative-free. Check out the MTHK Eye spray & Eye Drops.
Positive mental attitude & health: What’s good for the heart, is good for the brain, is also good for the eye. The link between mental health and eye health is clear, so make sure you look after yourself.

WHO IS MOST AT RISK OF GETTING DRY EYES?

Age: more common in people over 50, as tear production tends to decrease.
Gender: women are more likely, particularly those with hormonal changes related to pregnancy, birth control pill use, or menopause.
Diet: diets low in vitamin A (found in foods such as liver, carrots, and broccoli) or omega-3 fatty acids (found in fish, walnuts, and vegetable oils) can increase the risk of dry eyes.
Contact lenses: wearing contact lenses can also increase the risk of dry eyes.
Surgery: certain eye surgeries, such as corrective laser eye surgery (LASIK), cataract surgery, and cornea surgery, can increase the risk of dry eyes.
Environment & lifestyle: factors such as the weather, prolonged screen time, smoking, and allergies can contribute to dry eyes.
Medication: such as those used to treat depression, allergies, blood pressure, glaucoma, menopause, and pain, can increase the risk of dry eyes. Certain drugs, such as Anticholinergics, oral contraceptives, and systemic retinoids, can also lead to dry eye.
Underlying medical conditions: various neurological, eye, autoimmune, and endocrine disorders can also increase the risk of dry eyes.

“With the increasing use of screens, dry eyes are becoming more common in younger people”

PROFESSOR DAWN SIM, CONSULTANT OPHTHALMIC SURGEON AT MOORFIELDS EYE HOSPITAL, CO-FOUNDER AT MTHK.

What are tears & how do they work?

(i) MUCOUS (MUCIN) LAYER
Closest to your eyes is the mucin (mucous) layer. It sits atop the cornea, the clear part of the front of the eye, and provides a foundation for the other tear layers to maintain the right shape and stay in place.

(ii) WATERY (AQUEOUS) LAYER
In the middle is the aqueous (watery) layer, which provides moisture, oxygen and other nutrients to the cornea, affectionately called the ‘windscreen’ of the eye. It helps to wash away anything that gets into the eye, such as dirt, so the front of your eye stays smooth (so it can see and focus properly).

(iii) OILY (LIPID) LAYER
The top layer of tears furthest from your eye is the lipid (oily) layer. It floats on the tears and seals in the moisture of the aqueous layer underneath, making sure your tears are spreading over your eye correctly and stopping them from evaporating too quickly.

“Omega-3 fatty acids are found in the lipid (top) layer of your tears - so increasing your dietary intake will strengthen your tear film and help reduce tear evaporation. Choose foods rich in omega-3 and omega-6, such as oily fish, nuts, seeds, eggs and leafy greens.”

ALEX IONIDES, CONSULTANT OPHTHALMIC SURGEON AT MOORFIELDS EYE HOSPITAL, CO-FOUNDER AT MTHK.

Complications with Dry Eyes

Eye infections: Adequate tear production is necessary to protect the eye from infection. A lack of tears can increase the risk of eye infections.
Damage to the eye surface: If left untreated, severe dry eyes can cause inflammation, damage to the cornea, the formation of corneal ulcers and even vision loss.
Impacts daily life: Dry eyes can make it difficult to perform everyday tasks such as reading and negatively impact the quality of life.

Aqueous Deficient Dry Eye Symptoms

Aqueous deficient dry eye is when your eyes don’t produce enough tears. Your lacrimal gland (in the upper, outer corner of each eye) produces the aqueous (middle) layer of your tears. Some autoimmune conditions can cause inflammation in your lacrimal gland and prevent it from making enough of the aqueous layer.

Corneal sensory loss contributes to aqueous deficiency because corneal sensitivity plays a vital role in the blink feedback loop. When the tear film evaporates, a message is sent to the lacrimal gland to produce tears. When the sensation is diminished, the feedback loop is interrupted. Corneal sensory loss has many causes, including ageing, Cataract surgery (limbal incision), wearing contact lenses wear, and Laser Eye Surgery (LASIK). Obstructions in the lacrimal glands or ducts or other diseases of the lacrimal glands may also cause aqueous deficiency.

A suspected correlation between aqueous deficiency and hormonal imbalances — rising estrogen levels and dropping testosterone levels — occurs with the onset of menopause. Antihistamines, anti-depressants, chemotherapy drugs, and other drugs can contribute to aqueous deficiency. Aqueous deficiency can be caused by Sjögren’s Syndrome, an autoimmune disorder with sufferers complaining of dry eyes and mouth, among other symptoms. Other autoimmune diseases can also play a role in aqueous deficiency.

Clinical Procedures for Severe Dry Eyes

Punctal occlusion. During this painless procedure, the small tear-draining holes at the corner of the eye are blocked with tiny plugs to increase the volume of tears.
Thermal pulsation. Specialised devices provide controlled heat energy to the eyelids and massage them from the inside out and outside in. The heat breaks down obstructions in the meibomian glands and improves oil secretion.
Microblepharoexfoliation. A microsponge gently exfoliates the biofilm, removing crusting, bacterial colonies and mites that can infest the eyelashes.
Intense pulsed light. Non-laser light energy is applied to the eyelid skin to break down obstructions in the meibomian glands. This improves oil secretion, decreases eyelid redness and reduces spider veins.
Meibomian gland probing. This procedure clears glands of any obstructive scar tissue and hardened secretions.

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