Astigmatic Keratotomy

Overview

Incisions are made in the peripheral cornea to reduce astigmatism.

Brief description of procedure

After instillation of a drop of anaesthetic, the area is cleaned and sterilized. The eyelids are held open by a speculum then an arc of specific length and orientation is marked on the peripheral cornea parallel and close to the white of the eye. A specially designed diamond blade is set to cut a very exact depth, and then an incision is made along the pre-marked arc. This is painless but when the anaesthetic has worn off there is mild irritation for a few hours. The incision allows the cornea to bow out a little around the incision thus reducing astigmatism. The incisions are usually in pairs at each side of the cornea aligned on the astigmatism.

Experience

Routinely performed as a part of routine cataract surgery for more than 20 years.

Limitations

Increasing the depth, length and number of incisions increases the effect but only mild to moderate astigmatism can be corrected. Individual response varies so monitoring of the response is essential, increasing the treatment until an appropriate response is observed. Using this technique over-correction is rare and under-correction can be treated with repeat incisions. As with all operations there is a remote risk of infection.