Laser correction of your spectacle/contact lens prescription is a permanent procedure.
The permanent structure of the cornea is reshaped by laser to the shape of your glasses or contact lenses. Nothing is inserted into the eye.
In order to treat the permanent structure of the cornea the surface layer of skin (the epithelium) needs to be removed. This can be achieved by brushing the epithelium off (PRK) or creating a flap to lift and treat underneath the flap (LASIK). Both these treatments are restricted to the cornea.
PRK (Photorefractive Keratectomy)
PRK uses the excimer laser to change the curvature of the cornea. The surgeon prepares the eye by gently removing the epithelium (surface ‘skin’ layer of the cornea) to reveal the next layer of tissue. The computer-controlled laser then reshapes the curvature of the eye.
The laser treatment will last for seconds, although the toal procedure will take 15-20 minutes while the eye is prepared. The epithelium regenerates within 48-72 hours and follows the new curvature sculptured by the laser. Bandage contact lenses, which have no prescription, are placed over the eye. The patient is reviewed over the next three days.
LASIK (Laser In Situ Keratomileusis)
LASIK is an alternative procedure to PRK. While still using the excimer laser to reshape the cornea, the LASIK procedure requires a hinged corneal flap to be created first. This can be done using a precision automated device (micro-keratome) or with femtosecond laser technology which is blade-free. The flap is lifted, and then the cornea underneath is treated with the excimer laser.
Once the computer controlled laser is completed, the flap is returned to its original position without the need of sutures. Plastic, transparent shields are taped over the eyes overnight to prevent accidental knocking. These are removed by our staff the next morning and advised to be worn again during sleep for the next two nights.
PTK (Photo Therapeutic Keratectomy)
PTK is a procedure to improve the quality of the cornea. It may be used to treat various corneal degenerations, superficial scars, dystrophies and corneal irregularities. Unlike PRK or LASIK this technique does not correct refractive errors.
Like PRK the surgeon starts the procedure with a local anaesthetic drops followed by carefully removing the epithelium. The excimer laser then ablates an even layer of tissue (usually 5-10microns). A bandage lens is then placed on the cornea for the following few days as the corneal surface heals.
Corneal Cross Linking
Corneal Cross Linking is a procedure used to strengthen chemical bonds within the cornea. It is used to treat keratoconus and less frequently ectasia secondary to Lasik. The aim of the treatment is to stop active progressions of irregular changes to the cornea.
Unlike PRK and Lasik this procedure does not correct refractive error. The epithelium is gently removed from the cornea. The cornea is then soaked with riboflavin followed by exposure of ultra violet light which strengthens bonds between the collagen molecules. A contact lens is then placed over the cornea for the following three days as the epithelium regenerates.