Excimer laser photorefractive keratectomy using an erodible mask to treat myopic astigmatism.

PURPOSE

To evaluate the results of excimer laser photorefractive keratectomy (PRK) using an erodible mask to treat myopic astigmatism.

SETTING

Douglas Memorial Hospital Medical Centre, Fore Erie, Ontario, Canada.

METHODS

Photorefractive keratectomy was done on 25 consecutive eyes of 25 patients with myopic astigmatism using the OmniMed excimer laser and a compound single-use myopic erodible mask manufactured to produce a specific spherical and cylindrical correction for each individual patient. Follow-up ranged from 6 months for 25 patients to 1 year for 5 patients.

RESULTS

Six months after PRK, the mean preoperative sphere of -7.46 diopters (D) decreased to -0.17 D and the mean preoperative cylinder of 2.31 D dropped to 0.69 D; 73% of astigmatism was corrected. In the five eyes followed for 1 year, 94% of astigmatism was corrected. Correction of the myopic component was less predictable, with a wider than anticipated range of overcorrection.

CONCLUSIONS

Excimer laser PRK successfully corrected myopic astigmatism in patients with low and high myopia. The less predictable myopia results may have been secondary to increased procedure time, corneal dehydration, and difficulty in patient fixation and thus alignment.