PRK, LASEK, EPI-LASIK
Surface ablation procedures are alternatives to refractive surgery treatments to mainstream LASIK.
In general, surface ablation is performed on patients with either thin or steep corneas in order to preserve corneal strength. Occasionally, it is also performed on patients who participate regularly in contact or extreme sports such as boxing or are facing dry eyes issues as these group of people would benefit from a flapless procedure.
Surface ablation is a laser refractive procedure where the corneal epithelium is removed before laser ablation is applied to the underlying stroma in order to reshape the corneal surface. In myopia, the central corneal surface is flattened allowing the accurate re-focusing of light entering the eye. In hyperopia, the peripheral corneal surface is flattened instead.
A period of 3 to 5 days after surface ablation surgery is needed for healing during which time pain or discomfort is usually experienced. A bandage contact lens is used to aid healing. Visual recovery takes weeks to months before refractive stability is achieved at about 3 to 6 months.
Photorefractive keratectomy is a surface ablation method where the corneal epithelium is removed manually with a blunt instrument.
LASEK (Laser assisted subepithelial keratectomy) is a method of surface ablation where the corneal epithelium is removed with a dilute alcohol solution.
Epi-LASIK (Epithelial Laser in Situ Keratomileusis) is a surface ablation technique where the surface epithelium is cleaved off using a blunt automated blade called an epitome.
Photorefractive keratectomy, Laser-assisted subepithelial keratectomy (LASEK) and Epithelial Laser in Situ Keratomileusis (Epi-LASIK) are all surface ablation procedures and only differ in the method of epithelium removal. They all achieve equivalent visual acuity results.
The advantages of surface ablation include:
- No flap related complications
- Tissue saving
- Preservation of corneal strength
- Good outcome for lower degrees of myopia and astigmatism
The disadvantages of surface ablation include:
- Post-surgical discomfort of 3 to 5 days
- Longer visual recovery
- Longer use of eye medications
- Increased risk of corneal haze