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Advanced surface ablation (ASA) surgery is a type of refractive surgery. The aims of ASA surgery is similar to LASIK, which is to reduce spectacle or contact lens dependence. ASA can correct myopia, hyperopia and astigmatism.

In both ASA and LASIK surgeries, the cornea is re-shaped with the use of an excimer laser. The main difference is that in LASIK surgery, a corneal flap is created first, using a microkeratome blade or femtosecond laser, before the excimer laser is applied. In ASA surgery, no corneal flap is created. Instead, the most superficial layer of the cornea (the epithelium) is removed and the excimer laser is then applied to the cornea.

There several types of ASA surgery and they are categorised based on how the corneal epithelium is removed:

  1. PRK- this involves the use of a blade or brush to remove the epithelium
  2. Epi-LASIK – this involves the use of a special blade to remove the epithelium
  3. LASEK- alcohol is used to assist the removal of the epithelium
  4. TransPRK- this involves the use of laser to remove the epithelium

As one of the potential complication is the development of haze (corneal scarring), a chemical (mitomycin-C) is applied to the cornea during the ASA surgery.

ASA surgery comprises the following steps:

  1. The cornea epithelium is removed by 1 of the 4 methods listed above
  2. Excimer laser is applied to the cornea to re-shape the cornea
  3. Mitomycin-C is applied to the cornea
  4. A contact lens is placed on the eye

The main advantage of ASA surgery is that there is no corneal flap. Thus, there is no risk of an accident which may cause the corneal flap to be dislodged. The risk of dry eyes after surgery is also lower than LASIK surgery and it can be performed in patients with thinner corneas.

The disadvantages of ASA surgery is that it is more uncomfortable than LASIK and the discomfort can last for 5 to 7 days. The visual recovery is also much longer than LASIK surgery. In addition, there is a risk of haze formation.

ASA surgery can be done in any eye which is suitable for LASIK with lower refractive errors. It is most beneficial for patients with a higher risk of eye trauma, with dry eyes or those with thinner corneas.