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

Hi Chow

Corneal abrasions, or scratches to the corneal surface, cause what we call an 'epithelial defect'-a raw area not covered by the epithelial layer of cells of the eye.

This layer grows back and covers the 'epithelial defect' very quickly, usually within a couple of days for small to moderate abrasions.

Sometimes, the layer grows back and sticks back to the eye normally, and the patient has no further problems at all. Othertimes, as may have happened in your case, the epithelium grows back to cover the raw surface but does not stick back to the underlying layer properly-ie it remains 'loose'. As a result, the patient may develop recurrent eye pain-especially in the morning on waking. This is because the eyes dry out while sleeping, and upon waking, the upper eyelid may be slightly stuck to the corneal epithelium. If the epithelium is loose, the eyelid opening may loosen it further or even tear open the epithelium again. This is called recurrent corneal erosion syndrome and is usually treated with Duratears or similar eye ointment at night.

If you have recurrent erosion syndrome, you should not have conventional LASIK with a flap. The condition will remain a problem and may even worsen.

Recurrent corneal erosion syndrome is usually treated with night time ointment, but if this does not work, 'laser phototherapeutic keratectomy (PTK)' surface ablation is a very effective option. PTK is like epiLASIK or PRK, except that very little cornea is ablated since usually there is no intention to treat any spectacle power.

By the same token however, doing 'epiLASIK'/PRK will cure the recurrent corneal erosion syndrome while at the same time correcting the spectacle power-ie killing 2 birds with one stone. epiLASIK/PRK is basically PTK but done with a slightly different pattern and going deeper into the cornea.

Bear in mind that you still need the usual checks for suitability if you are thinking of correcting the myopia, since you need to ensure sufficient corneal thickness etc. Doing it for high myopia does carry a somewhat higher risk of haze/scarring, but this risk can be minimised by using a medicine called mitomycin C for a sufficient length of time.

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). Both epi-LASIK and LASIK are primarily considered to be refractive surgery. Though epi-LASIK and PTK have many similarities in terms of benefits, risks and gradual process of recovery.

A limitation to having PTK or epi-LASIK in your case may be the level of myopia, which is considered high. Epi-LASIK is an excellent option in low to moderate levels of myopia. The concern with high myopes undergoing epi-LASIK is the associated increased risk of corneal haze and inflammation. These complications may result in sub-optimal refractive results by way of regression and blurring of vision.

You would be best served by undergoing a thorough eye evaluation to ascertain your suitability for any form of refractive surgery. Ensure your surgeon is willing and able to offer you the entire range of surgical options. That way, the advice can be customised to your eyes and overall aims.

I wish all the success in your search for spectacles independence.

Dr David Chan

Recurrent corneal erosion may result from traumatic abrasion of the cornea, and is usually treated by copious lubrication. In cases that keep recurring it can also be treatable by purposely inducing pinpoint areas of micro-scars on the superficial layers of the cornea, to make the surface layers become more adherent.

In the old days this was done by simply using very fine needles. Nowadays doctors can use the excimer laser to do this in a treatment called PTK. This in itself does not alter the eye power more than around 50 degrees.

It can be combined with a surface ablation refractive treatment and you can consider transPRK for this, as this is basically a combi of PTK and refractive excimer treatment, and is a no-touch treatment. EpiLASIK uses a blunt blade and may not be the first choice as it can potentially cause problems if there are significant scars on the cornea.

It is advisable to undergo a very thorough test of your eyes before any elective laser treatment in cases like yours, as occasionally your symptoms may be associated with an underlying cornea disease called dystrophy, which may be quite subtle in the early stages. Blood tests can be performed to rule out certain types of these cornea diseases.

If all is cleared and your cornea thickness measurements are ideal for surface ablation techniques, you should definitely consider having MMC to reduce haze, which is more likely to occur after surface ablation for higher power. MMC is recommended for surface ablation from 500 deg onwards.

If your cornea measurements are inadequate for surface ablation, an alternative may be to consider PTK to treat the corneal erosions, and consider ICL later on for refractive correction.

All the best and take care there!

Dr Han