AK (Astigmatic Keratectomy)
AK is performed to correct astigmatism (i.e., misshapened cornea), one of the causes of blurry sight. To correct the deformity by making the cornea spherical, several incisions are made at the steepest part of the curve, causing that area to relax and lesson its curvature. Because astigmatism is often accompanied by other eye abnormalities, AK is often performed in combination with other refractive procedures.
The results of AK are less predictable than with other eye-surgery procedures. About a third of those patients who undergo AK find that their eyes regress to a considerable degree and only a small improvement is noted. Another third find that the astigmatism has been significantly reduced, but not fully corrected. The remaining third experience most to all of the desired correction.
Following is what to expect during a typical AK procedure:
1. A full eye examination is performed and the degree of refraction determined. Pre-op sedation is given if desired and the cornea is topically anaesthetized.
2. The patient is reclined in the surgical chair and positioned under the operating microscope. The center of the pupil is marked and the appropriate areas of the cornea to be incised are marked using a gentian violet marker.
3. A diamond blade is used to incise the cornea, debris washed out of the incisions and a topical antibiotic applied. The eye is then patched and the patient discharged.
4. Following the procedure, generally little more than a scratchy eye sensation is experienced for about a day. Antibiotic drops are used four times daily to prevent infection. The refraction may fluctuate for about a month, at which time enhancement may be performed if necessary. A conservative approach to surgery is best to avoid overcorrection.