Utilizing the accuracy and precision of the excimer laser, LASIK changes the shape of the cornea to improve the way light is focused or “refracted” by the eye. By adjusting the pattern of the laser beam through its computer, it is possible to treat high levels of nearsightedness, farsightedness and astigmatism.
LASIK surgery is performed as an outpatient procedure in the comfort and convenience of the excimer laser surgical suite. The entire vision correction procedure takes less than 30 minutes and both eyes are done the same day. The procedure is performed using topical anesthesia (eye drops). Some patients report a slight, post-operative discomfort that can usually be alleviated with medications. Patients see a dramatic improvement in their vision within the first day. Most patients return to their normal activities within a day or two.
Step by Step
The LASIK procedure takes a few minutes to complete, and the procedure is relatively painless. Patients are always amazed at the ease of this procedure because of speed and comfort. Only topical anesthetic drops are used to numb the eye for the procedure. An eyelid holder is inserted to prevent blinking while the drops eliminate the reflex to blink.
Step 1
A suction ring is placed on the eye to secure the eye and maintain pressure within the eye while the corneal flap is created. A microkeratome, an automated microsurgical instrument similar in design to a carpenter’s plane, is used to create a thin corneal flap which remains hinged beneath the upper eyelid.
The corneal flap is 160 to 180 microns thick, about 30% the corneal thickness which is typically about 550 microns. Patients do not feel or see the cutting of the corneal flap, which takes only a few seconds. Corneal “flap making” has been researched and developed for 40 years, providing us with a long history of safety and stability.
Step 2
The corneal flap is then laid back and the inner stromal layers of the cornea lasered with the patient’s prescription. An ultraviolet light from the excimer laser reshapes the internal cornea with an accuracy of 1/2000th of a milimetre.
For reshaping the cornea, the corneal surface is polished with the help of a pre-programmed excimer laser. This changes the refractive power of the cornea thus eliminating the refractive error of the eye.
Step 3
The corneal flap is then repositioned and the flap and interface rinsed. Once the procedure is completed, the surgeon will wait 2 to 3 minutes to ensure the corneal flap has fully re-adhered.
At this point, patients can blink normally and the corneal flap remains secured in position by the natural adherence within the cornea. While it is possible to dislodge the corneal flap during the first day or two by physically rubbing the eye, this event is actually quite rare. After the first week, LASIK patients can resume their full exercise activities.
Since the protective layer remains intact with LASIK, no bandage or contact lens is required. However, a protective eye shield is normally recommended for a day. LASIK patients are placed on an antibiotic and anti-inflammatory drop regimen for about 1 week. They also need to instill artificial tears for a few months. Patients are able to travel by air immediately and exercise after 1 week.
LASIK is generally considered the method of choice for using the Excimer Laser for correcting refractive errors. Another popular technique is Photo Refractive Keratectomy or PRK. LASIK is generally the method of choice because it allows faster post-operative recovery of vision, requires less follow-up, and allows the patient to be more comfortable faster. However, there are circumstances under which it is more appropriate to use PRK in some patients.