LASIK
In Laser in-situ Keratomileusis (LASIK), a corneal flap is created with a Femtosecond Laser, followed by Excimer Laser ablation to reshape the cornea to correct the refractive error (All-laser, No-blade technique).
Step 2
The corneal flap is lifted and
Excimer Laser with
eye tracking is used to reshape the cornea to correct the refractive error.
Step 3
The corneal flap is then replaced.
Advanced Surface Ablation
In Advanced Surface Ablation, the cornea is reshaped by the Excimer Laser from the surface rather than under a corneal flap like in LASIK.
Step 1
The most superficial "skin" layer of the cornea (epithelium) is removed.
Step 3
A contact lens is placed onto the eye for 5-7 days to allow the epithelium to grow back.
Variations of Advanced Surface Ablation
During Advanced Surface Ablation, the "skin" layer (epithelium) of the cornea is removed.
In
Trans-epithelial Photorefractive Keratectomy (TransPRK), the epithelium is removed and reshaping of the cornea is performed both by using the Excimer Laser in a single continuous step. (i.e. Laser removal of epithelium)
In
Epithelial Laser in-situ Keratomileusis (EpiLASIK) , the epithelium is removed using a mechanical separator. This is then followed by
Excimer Laser treatment to correct the refractive error. At the end of the procedure, the sheet of epithelium is replaced and a bandage contact lens is placed over the cornea to aid healing (i.e. Mechanical removal of epithelium).
Laser Assisted Sub-Epithelial Keratomileusis (LASEK) differs from EpiLASIK in that the epithelium is separated and removed using alcohol. At the end of the procedure, the sheet of epithelium is replaced and a bandage contact lens is placed over the cornea to aid healing (i.e. Chemical removal of epithelium).
Non-Laser Options
Implantable Contact Lens
In patients where
LASIK or
Advanced Surface Ablation is not suitable due to extreme high myopia or insufficient corneal thickness, Implantable Contact Lens (ICL) may be an option.
An artificial lens can be implanted into the eye in front of the patient's natural crystalline lens through a small incision in the cornea. The advantage of ICL is that it is able to correct very high degrees of myopia and hyperopia, in addition to astigmatism.
Unlike LASIK or Advanced Surface Ablation which are external ocular procedures, ICL is a more invasive intraocular surgery. Its potential risks, albeit small, are more serious. This includes corneal swelling, intraocular inflammation, glaucoma, cataract, retinal tear and intraocular infection.
As such, ICL is only recommended as a secondary option for patients who are not suitable for LASIK or Advanced Surface Ablation but are still keen for refractive surgery.
Corneal Cross-linking
Corneal cross-linking is a procedure whereby Riboflavin (Vitamin B2) eye drops and Ultraviolet (UV) light are used to strengthen the cornea by inducing cross bonding of the collagen fibres within the cornea, thereby preventing corneal warpage over time. It has been used by some centres in combination with LASIK to strengthen the cornea after
Excimer Laser ablation. However, its main application is in treating conditions such as keratoconus and post-LASIK corneal weakening.