PHOTOREFRACTIVE KERATECTOMY WITH A TRANSITION ZONE FOR MYOPIA FROM -7TO -14 DIOPTERS

PURPOSE: To study transition zone excimer laser photorefractive kerate ctomy (PRK) in moderate and high myopia defined as a spherical equival ent of -7.00 diopters (D) or more. The follow-up period was 18 months. METHODS: Forty eyes of 40 patients with myopia of 7.00 to -13.50 D (m ean +/- SD, -921 +/- 1.98) underwent transition zone (5.0 to 7.0 mm tr ansition zone) PRK using the Aesculap Meditec Mel 60 excimer laser. Th e mean attempted correction was 8.3 +/- 1.64 D (range: -6.50 to -12.00 D). RESULTS: At 18 months, 83% achieved an unaided visual acuity of 2 0/50 or better and HOW 12% 20/25 or better. Eighty-eight percent were within +/- 2 D of emmetropia. The mean spherical equivalent was -1.1 D (+3.00 to -9.00 D). CONCLUSIONS: Transition zone PRK is useful in mod erate to high myopia. Regression, as well as overcorrection are issues for further investigation.