As compared to LASIK patients, why do Epi-LASIK patients tend to have residual degree instead of perfect eyesight after surgery?

Doctor's Answers 2

Actually, the basis of your question ie that epi-LASIK patients tend to have residual degree as compared to LASIK patients is not necessarily true. For example, in this Cochrane Database Review meta-analysis comparing LASIK with PRK (which is the same as epi-LASIK) https://www.ncbi.nlm.nih.gov/pubmed/23440799, the authors concluded that 'The two techniques appear to give similar outcomes one year after surgery.'

What's more important, I believe, is to understand why certain patients may do better with a particular technique, and also to understand the different pros and cons of LASIK versus epi-LASIK/PRK.

LASIK gives fast visual recovery and much better post-operative comfort, though with the rare possibility of flap problems. PRK/epi-LASIK/LASEK eliminates the possibility of flap problems but besides slower visual recovery and increased post-operative pain, also has a higher risk of post-operative corneal haze/scarring (which is virtually unknown with LASIK).

As such, it is my routine practice to use an anti-scarring medicine called Mitomycin C (MMC) for PRK/epi-LASIK patients, to markedly reduce the risk of corneal haze. This haze, if bad enough and thick enough, may indeed cause some amount of residual degree or regression, and may be a cause for the notion some people have that epi-LASIK patients tend to have residual degree as compared to LASIK patients. When MMC is used, though, it is extremely rare to see such haze, except in some patients with high spectacle degrees.

With the proper use of medication, and the proper selection of procedure, the 2 techniques generally do give similar outcomes after full recovery has occurred.

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Dr E-Shawn Goh

Ophthalmologist

In general, published results for Epi-Lasik and femto-Lasik procedures are comparable, meaning that they are both equally effective at correcting patients with myopia / hyperopia and astigmatism.

If you are referring to anecdotal examples of your friends who may report more frequent concerns of residual refractive error, you should consider that selection bias may have played a role in your observation, as patients who undergo epi-Lasik are usually not suitable for femto-Lasik (due to the combination of high refractive error, and thin corneas).

It is likely that these factors are the true cause of what you are observing. Namely that high pre-surgery refractive error increases the likelihood that a patient may need an enhancement, and a thin cornea / low residual cornea thickness means that the risk of regression is higher.

E-Shawn Goh

Similar Questions

Is Epi-LASIK or LASIK better if I have a history of corneal abrasion due to contact lens wear?

This is an excellent question. It seems like you may be suffering from a known complication following trauma to the eye, specifically the window of the eye known as the cornea. Occasionally, the surface of the cornea may become fragile and prone to spontaneous abrasion or the medical term used is recurrent corneal erosion. In this particular situation, advanced surface ablation may help to stabilise the cornea to prevent further spontaneous abrasion. Strictly speaking, the term used for treatment in this situation is called photo-therapeutic keratectomy (PTK).

Can I have LASIK surgery if I had strabismus surgery at a young age and have high astigmatism?

Thanks so much for your enquiry. Previous strabismus surgery is certainly not a contra-indication to performing refractive surgery now. You should however undergo a comprehensive assessment with your refractive surgeon Ophthalmologist so that you can discuss the most appropriate form of treatment for you in view of your high astigmatism. Best of luck!

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Answered By

Dr E-Shawn Goh

Ophthalmologist

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