Services » Laser Corrective Eye Surgery
LASIK is a surgical procedure using the Star4 excimer laser to correct nearsightedness (myopia), farsightedness (hyperopia) or nearsightedness with astigmatism. In LASIK, a thin flap of surface corneal tissue is created using a device known as a microkeratome. This is done to allow access to the underlying corneal tissue known as the stroma. With the stroma exposed, multiple pulses of Star4 excimer ultraviolet light are applied to the cornea in a computer-controlled pattern, in order to remove a precise amount and pattern of stromal tissue. Therefore, following replacement of the flap, the net result is that the front surface of the cornea is reshaped (for nearsightedness or myopia, this includes flattening of the central curvature of the corneal surface). By reshaping the central cornea curvature, the focussing point of light rays entering the nearsighted eye (with or without astigmatism) is brought closer to the retina (the sensitive tissue lining the back of the eye that acts like the film in a camera) and the uncorrected distance vision is improved. Farsightedness can be corrected by reshaping the central cornea curvature so that it becomes more steeply curved, again allowing light rays to be brought closer to the retina.
In the clinical studies of the VISX Excimer Star S2 Laser System for nearsightedness, farsightedness and astigmatism, the results of the 12 months after surgery were:
A. Without the help of glasses
- 94% mildly nearsighted eyes could see 20/40 or better
- 91% mildly nearsighted eyes with astigmatism could see 20/40 or better
- 90% highly nearsighted eyes with or without astigmatism could see 20/40 or better
- 95% moderately farsighted eyes could see 20/40 or better
B. With the help of glasses*
- 99% mildly nearsighted eyes could see 20/40 or better
- 98% mildly nearsighted eyes with astigmatism could see 20/40 or better
- 99% highly nearsighted eyes with or without astigmatism could see 20/40 or better
- 99% moderately farsighted eyes could see 20/40 or better
- Data collected from eyes that could see 20/20 or better with glasses before surgery
Even though vision improves without glasses, some patients may need and enhancement, glasses, or contact lenses after LASIK. LASIK does not eliminate the need for reading glasses. NOTE: you may need reading glasses after laser surgery even if you did not wear them before.
The LASIK Procedure
LASIK is performed as an outpatient procedure. Anesthetic (numbing) eyedrops are placed in the eye immediately prior to surgery in order to minimize discomfort during the procedure. In some cases, a mild sedative pill may be administered to reduce apprehension prior to surgery. The eyelid is cleansed and held open using a special instrument. The other eye is covered with a patch during the treatment.
During the LASIK procedure, the surface cells on the cornea usually remain intact. The first step of the procedure involves a device known as a microkeratome to create the corneal flap. In order to do this accurately, the pressure inside the eye needs to be raised to extremely high levels. This is accomplished with a suction ring placed on the white of the eye. When the suction ring is activated, the pressure inside the eye is confirmed to be sufficiently elevated and the microkeratome is used to cut a partial thickness (generally less than 1/3 of total corneal thickness) section of corneal tissue. In the vast majority of cases, the microkeratome is stopped before it completely goes across the cornea, creating the desired hinged flap. In rare cases a full round disc is sectioned (called a cap). After the flap is created, it is retracted exposing the underlying stroma.
With the underlying corneal tissue exposed, the laser application begins. This usually takes 30 - 60 seconds depending on the amount of nearsightedness, farsightedness and /or astigmatism that is being treated. The exact number of pulses delivered by the laser is calculated by the laser's computer. During the procedure, the patient will hear a load snapping sound and may detect a slight odor (resulting from the interaction of laser light and the corneal tissue).
After the laser treatment, the flap is put back in its original position (a cap can be similarly replaced into position) without sutures. Antibiotic and anti-inflammatory eye drops are placed in the treated eye after the procedure is completed.
In the immediate post-operative period, the patient may notice his/her vision to be significantly improved compared to before surgery. Best vision, however, may take several days or weeks to achieve. Because of this, and also because of potential effects of any sedatives administered, the patient will not be allowed to drive home. Surgery will not be performed unless a driver is present or other arrangements have been made.
During the early post-operative period, the LASIK patient is examined the next day and potentially every 24-48 hours until the corneal surface heals. Depending on the amount of blurriness and light sensitivity, the patient may need a driver during this early postoperative period. Although the patient usually feels no discomfort during the actual LASIK procedure, there may be very mild discomfort for the first few days after surgery. This may require the use of pain reducing medications and artificial tear drops. Most patients, however are extremely comfortable during the entire postoperative course.
A major concern in the early postoperative period following LASIK is dislodging the flap or cap. It is generally believed that this is most likely to occur in the first 1-2 weeks after surgery and can be caused by vigorous eye rubbing, fingernails, or other injuries to the surface of the eye. Patients will be asked to avoid rubbing their eyes and to wear protective eye shields when they go to sleep for the first few days after surgery.
The postoperative medication regimen is reviewed with the patient both before and after surgery and also with the patients driver prior to discharge on the day of surgery. The patient is evaluated one day after surgery, then at one week and one month. Additional visits may be scheduled as necessary.
In order to minimize the risk of infection and postoperative discomfort, as well as maximize the visual result of the LASIK procedure, it is important for the patient to comply faithfully with medication dosages and schedules. Medications are usually necessary for only a few weeks after LASIK, although in uncommon cases they may be required for up to several months. Additional postoperative visits occur with progressively greater intervals depending upon the patient's clinical course.
Although in the vast majority markedly improved uncorrected vision is generally noted quite soon after LASIK, an individual patient's best vision may not be realized for several weeks or months after surgery. Delayed visual recovery following LASIK may be the result of, among other factors, surface epithelial defects, folds in the flap or cap, improper positioning or dislodging of the flapor cap, or haze/scarring in the interface ... the underlying corneal tissue.
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