6 min



What is LASIK & how does it work?

We talk about LASIK* in this article, as it’s the most performed laser refractive surgery, accounting for approximately 95% of all procedures.

LASIK is a standard surgical procedure used to correct vision problems - specifically, those caused by refractive errors. In eyes with normal vision, the cornea bends (refracts) light precisely onto the retina at the back of the eye. A refractive error is where your cornea fails to bend light correctly, distorting your vision. It can cause blurry vision (astigmatism), nearsightedness (myopia) or farsightedness (hyperopia).

LASIK* is an acronym for “laser-assisted in situ keratomileusis.” In situ means “in place” and “keratomileusis” is the medical term for reshaping your eye’s cornea.

“After the surgery, the cornea may be temporarily weakened. This can cause the eyes to produce fewer tears, leading to dry eyes.”

What vision problems can be treated by LASIK?

  • Myopia (Short-Sightedness): When your eyeball is slightly longer than normal or when the cornea curves too sharply, light rays focus in front of the retina and blur distant vision. You can see objects that are close reasonably clearly, but not those that are far away.
  • Hyperopia (Long-Sightedness): Hyperopia is the opposite of myopia. You can see objects far away but struggle with those up close. In this case, you have a shorter-than-average eyeball or a too-flat cornea; light focuses behind the retina instead of on it.
  • Astigmatism (Blurred Vision): Astigmatism occurs when the cornea curves or flattens unevenly, blurring your focus on nearby and distant objects.

Is LASIK safe?

Results vary from centre to centre, but around 90% of people who undergo laser eye surgery have vision between 20/20 and 20/40 (without glasses or contact lenses).

20/20 vision is normal, healthy vision — not “perfect” vision. With 20/40, you can see at 20 feet what an average person sees at 40 feet.

Studies have shown that an average of 95% of individuals who have had laser eye surgery are satisfied with the results.

Check Your Eye Health - 60-Second Eye Test

What are the potential side effects of LASIK

  • You might notice increased light sensitivity, glare, halos around bright lights or double vision. Your vision in dim light (such as dusk or fog) may be reduced. You may also have difficulty seeing at night after surgery, usually lasting a few days to a few weeks.

  • Dry Eyes are a common side effect of LASIK surgery, which sometimes resolves on its own within a few weeks or months. After the surgery, the cornea may be temporarily weakened. This can cause the eyes to produce fewer tears, leading to dry eyes. In some cases, dry eye after laser eye surgery may be more severe and require treatment. This can include using artificial tears (Drops & Sprays) to moisten the eyes or taking other steps to stimulate tear production (including dietary supplements).

  • Under corrections are more common for short-sighted people. If the laser removes too little tissue from your eye, you won’t get the clearer vision results you hoped for. You may need another procedure within a year.

  • Over-corrections may be more challenging to fix than under-corrections. It’s also possible that the laser will remove too much tissue from your eye.

  • Astigmatism can be caused by uneven tissue removal. It may require additional surgery, glasses or contact lenses.

  • Folding back or removing the flap from the front of your eye during surgery can cause complications, including infection and excess tears. The outermost corneal tissue layer may grow abnormally underneath the flap during healing.

  • Regression is when your vision slowly changes back toward your original prescription. This is a less common complication.

  • Eye discomfort, pain or sensitivity to light. In some rare cases, tiny red or pink blood patches on the whites of your eyes.

  • As with all surgical procedures, there is a small risk of infection.

  • Rarely, surgical complications can result in loss of vision. Some people also may not see as sharply or clearly as previously.

  • How long does the LASIK procedure take?

    You will be awake during the surgery, which typically takes less than 30 minutes. (Note: you should not drive yourself home after the surgery.)

    A laser makes a small cut, or flap, in the cornea. This flap is lifted, and the laser removes a tiny amount of tissue from the cornea. The flap is then placed back into its original position, where it will heal on its own.

    Your Complete Guide To Dry Eyes

    How much does LASIK cost?

    The cost of LASIK surgery can vary depending on several factors (location of the surgery, the experience /qualifications of the surgeon, technology used, etc.).

    On average, LASIK surgery can cost anywhere from £1,000 to £4,000 per eye - but it can be higher or lower depending on the above factors.

    The NHS or insurance plans do not typically cover LASIK, so patients may have to cover the cost. However, some surgeons or clinics offer financing options to help make the surgery more affordable.

    “You might notice increased light sensitivity, glare, halos around bright lights or double vision”

    How long does it take to recover from LASIK?

    Recovery time from laser eye surgery is quick. You might be able to return to most of your normal activities as early as the day after the procedure (including driving).

    Other activities may take a bit longer:

    • Don’t wear eye makeup for 2 weeks.
    • Avoid playing non-contact sports for 3 days and contact sports for 4 weeks.
    • Wear an eye shield at night for at least 4 weeks.
    • No swimming for at least a month.

    Who is a good candidate for LASIK?

    • If you wear glasses or contact lenses.
    • Are over 18 (though your ophthalmologist might prefer you to be 21 or older).
    • Your eye prescription is stable (i.e. hasn’t changed in the past year).
    • Your eyes are generally healthy (especially your corneas, which need to be thick without scratches).

    Your ophthalmologist or surgeon will consider the above factors and others before deciding if you’re a good candidate for LASIK.

    Who is NOT a good candidate for LASIK?

    LASIK may not be an option

    • If the prescription in your eyes is unstable or changing.
    • Your astigmatism (blurry vision), myopia (short-sightedness) or hyperopia (long-sightedness) is extreme.
    • You have severe dry eyes.
    • You have Cataracts.
    • You have uncontrolled diabetes.
    • You have a history of eye infections.
    • You have Glaucoma at an advanced stage.
    • You have rheumatoid arthritis or Crohn’s disease.
    • You have keratoconus (cone-shaped cornea).
    • You’re pregnant or breastfeeding.

    “A laser makes a small cut, or flap, in the cornea. This flap is lifted, and the laser removes a tiny amount of tissue from the cornea. The flap is then placed back into its original position, where it will heal on its own.”

    Is flying safe after laser eye surgery / LASIK

    Your surgeon will provide specific guidelines for flying after laser eye surgery, as the recovery time can vary depending on the procedure.

    It is generally safe to fly once the eye has healed sufficiently and your surgeon has given you clearance. Make sure to follow any post-operative care instructions provided by your surgeon while travelling.

    Eye Care Guide To Healthy Flying

    What happens during LASIK?

  • After lying flat, your ophthalmologist/surgeon will use eye drops to numb your eyes. Although you won’t be in pain, you might feel pressure during the procedure - like a finger pressing against your eyelid.

  • An eyelid holder and suction ring will be placed on your eye. The holder will keep you from blinking, and the ring will keep your eye from moving. Your vision will dim or possibly go completely black.

  • Laser makes a flap. With precise eye measurements, a pre-programmed laser will create a flap (as thin as a sheet of paper) on your cornea. It’ll then lift and fold that flap back.

  • Next, the ophthalmologist will get you to stare at a light - which keeps your eyes from moving. The laser is used again to reshape your cornea to refract light better. The laser might make a clicking/ticking sound. You might smell the scent of burned hair.

  • And finally, your ophthalmologist will fold the flap of tissue back down. It will start to heal quickly — settling into place within a few minutes.


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    Complete Guide To Laser Eye Surgery (LASIK) - Resources & References

    1. American Academy of Ophthalmology. (2019). What is LASIK? Retrieved from https://www.aao.org/eye-health/treatments/what-is-lasik
    2. Mayo Clinic. (2021). LASIK eye surgery. Retrieved from https://www.mayoclinic.org/tests-procedures/lasik-eye-surgery/about/pac-20384774
    3. National Eye Institute. (2020). Refractive Errors. Retrieved from https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/refractive-errors
    4. U.S. Food & Drug Administration. (2018). LASIK - What to know before LASIK.
    5. The Royal College of Ophthalmologists. (2016). Laser Vision Correction (LASIK, LASEK, PRK and SMILE).
    6. American Society of Cataract and Refractive Surgery. (2021). LASIK - Laser Eye Surgery. Retrieved from https://ascrs.org/patients/procedures/lasik
    7. Cleveland Clinic. (2020). LASIK Eye Surgery: Risks, Recovery & How it Works. Retrieved from https://my.clevelandclinic.org/health/treatments/24546-eye-surgery
    8. American Optometric Association. (n.d.). LASIK and Refractive Surgery.