Advanced Surface Laser Ablation (ASLA)

Advanced Surface Laser Ablation (ASLA)
By Lawrence Ocampo

The ASLA (Advanced Surface Laser Ablation) technique is used when the LASIK (LAser in SItu Keratomileusis) procedure is considered unsuitable for a particular patient, for example, if the cornea is too thin or if the corneal topography is irregular or if the corneal surface layer (the epithelium) is unstable. ASLA can be used for correction of myopia or astigmatism, but it is not used for correcting hypermetropia.

Here's a detailed description of how the procedure is done. The ASLA procedure takes about 15 minutes per eye. First, the cornea is anaesthetized. Next, anaesthetic drops are applied to the eye, and an eyelid holder is put in place to keep the eye from blinking. Additionally, anti-inflammation eye-drops are applied to the cornea in order to reduce the post-surgical reaction and discomfort. The corneal epithelium layer is removed afterwards. The front surface layer of the cornea (epithelium) is then gently lifted away from the rest of the cornea. This exposes the corneal 'bed' which is now ready to receive the energy from the laser beam. The cornea is now re-shaped by the laser. The laser beam, consisting of UV energy, vaporizes a pre-determined amount of tissue from the corneal bed, thus giving the cornea the new shape required to correct the eye's optical prescription. Then, the loose epithelium tissue can be placed back over the corneal bed. A soft contact lens is applied afterwards. After this, the eye is fitted with a "band-aid" soft contact lens for added protection while the surface of the eye heals. Antibiotic eye-drops are also applied. Anti-inflammation eye-drops are prescribed.

About 4 days after surgery, the contact lens is removed, and a course of mild anti-inflammation eye-drops is commenced. The ASLA technique is similar to the PRK (PhotoRefractive Keratectomy) and LASEK (LASer Epithelial Keratomileusis) techniques, but with some refinements to aid the recovery of the eye. It is possible to have both eyes treated on the same day. For post-operation visual recovery, it can take 4 days or more for patients to achieve useful vision. The eyes usually feel gritty and sore for about 2 days after surgery and, in some cases, they may even feel painful initially after the surgery. Stabilization takes about 1-2 months. A mild haze may be present for a few weeks.