Comparison of results of excimer laser correction of all degrees of myopia at 12 months postoperatively. The Melbourne Excimer Laser Group.

Abstract

To examine prospectively the efficacy and safety of photorefractive keratectomy and photoastigmatic refractive keratectomy. We treated 645 eyes (440 patients) with a VisX Twenty/Twenty excimer laser and followed them up for 12 months. The percentage of eyes with myopia between -5.01 and -10.00 diopters spherical equivalent within 1 and 2 diopters of emmetropia at 12 months was 65% (123 of 189) and 90% (170 of 189), respectively, whereas the corresponding percentages for eyes with myopia greater than -10.00 diopters spherical equivalent were 39% (16 of 41) and 56% (23 of 41), and for eyes with myopia of -5.00 diopters spherical equivalent or less, 87% (238 of 273) and 99% (270 of 273), respectively. Uncorrected visual acuity of 20/20 and 20/40 or better at 12 months was attained in 47% (129 of 273) and 87% (237 of 273) of the eyes with myopia -5.00 diopters spherical equivalent or less, respectively. At 12 months, 48 (25%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 or better and 135 (71%), 6/12. At 12 months, one eye (2%) with myopia greater than -10.00 diopters spherical equivalent had uncorrected visual acuity of 6/6 and 11 (27%) of 41 eyes, 6/12. Ten (4%) of the 273 eyes with myopia of -5.00 diopters spherical equivalent or less, 15 (8%) of the 189 eyes with myopia between -5.01 and -10.00 diopters spherical equivalent, and nine (22%) of the 41 eyes with myopia greater than -10.00 diopters spherical equivalent had lost two or more LogMAR lines of best-corrected visual acuity at 12 months. Excimer laser surgery is highly reliable for myopia of -5.00 diopters spherical equivalent or less and is less reliable for greater myopia.