Photorefractive keratectomy for myopia with a 6-mm beam diameter

Abstract

Background: Earlier studies have reported clinical outcomes for up to 2 years following photorefractive keratectomy (PRK) using a 5.0-mm treatment zone with the Summit excimer laser. We present results of PRK using a 6-mm ablation zone with the same laser.

Methods: Forty-five eyes of 45 patients underwent excimer laser PRK for correction of myopia using a 6-mm excimer laser beam diameter. Attempted corrections ranged from 1.50 diopters (D) to 6.00 D. Data on outcomes of uncorrected visual acuity, spectacle-corrected visual acuity, predictability, corneal haze, subjective glare/halo effects, and patient satisfaction with the procedure were analyzed over a follow-up period of 6 months.

Results: All patients obtained a postoperative uncorrected visual acuity of at least 20/40; 28 eyes (62%) achieved at least 20/20. Postoperative spectacle-corrected visual acuity was at least 20/20 in all patients; no patients lost more than one Snellen line of spectacle-corrected visual acuity. Twenty-eight patients (62.2%) achieved within +/-0.50 D of the attempted correction; 40 patients (84.4%) achieved within +/-1.00 D. Mean spherical equivalent refraction was -4.99 D preoperatively and +0.44 D at 1 month, +0.04 D at 3 months, and +0.09 D at 6 months. At 6 months, 40 eyes (88.9%) were graded as clear, 4 eyes (8.9%) as having trace subepithelial haze, and 1 eye (2.2%) as having mild subepithelial haze. The mean glare/halo index for all of the patients was 0.59 on a scale of 0 to 5. Mean subjective patient satisfaction was 4.68 (on the same scale).

Conclusions: Clinical outcomes following excimer laser PRK for myopia using a 6-mm treatment zone are encouraging. Postoperative subjective glare/halo were minimal, suggesting an optical advantage in using the larger ablation zone.