PHOTOREFRACTIVE KERATECTOMY FOR ASTIGMATISM GREATER-THAN -2.00 DIOPTERS IN EYES WITH LOW, HIGH, OR EXTREME MYOPIA

Purpose: To assess the efficacy of excimer laser photorefractive astig matic keratectomy (PARK) in correcting astigmatism of more than -2.00 diopters (D) in eyes with low, high, and extreme myopia. Setting: Pusa n National University Hospital, Pusan, Korea. Methods: Eighty-five pat ients (110 eyes) whose spherical error ranged from -3.00 to 13.00 D an d cylinder ranged from -2.00 to -5.50 D had PARK with a VISX Twenty-Tw enty excimer laser; follow-up was 6 months. All cases of myopic astimg atism were treated using the elliptical method and multizone ablation technique. Eyes were divided into 3 groups: low myopia, less than 6.00 D (n = 47): high myopia, from 6.25 to 10.00 D (n = 43); extreme myopi a, over 10.25 D (n = 20). Alpins vector analysis was used to calculate the astigmatic change. Results: By vector analysis, the success rate of astigmatic correction was more predictable int he low and high myop ia groups than in the extreme myopia group (P < .05). There was little improvement in astigmatism in the extreme myopia group. Conclusion: U sing PARK to correct astigmatism greater than -2.00 D in eyes with myo pia less than -10.00 D tended to result in undercorrection; astigmatic correction in eyes with myopia over 10.25 D was minimal.