Double-pass excimer laser photorefractive keratectomy: treatment in 62 eyes with high myopia

To evaluate the efficacy and safety of Excimer Laser Photorefractive Keratectomy (PRK) on the correction of high myopia, we performed planned double-pass PRK procedure at the same session on 62 eyes of 55 patients with myopia ranging from -6.30D to -15.25D (mean, -9.94D). In the first pass, a myopic correction of -6.00D with a 4.5 millimeter ablation zone was performed, and immediately after, a second correction of remaining myopia with a 5.0 millimeter ablation zone was performed. Attempted correction ranged from -6.30D to -9.50D (mean, -8.70D). The eyes were divided into two groups which were -10.50D or less (group A), and higher than -10.50D (group B). All the eyes received topical corticosteroid therapy postoperatively. One year after double-pass PRK, uncorrected visual acuity in group A and B improved to 20/40 or better in 84.0%, and 73.3% of the eyes and to 20/30 or better in 75.0% and 33.3% of the eyes respectively. The mean refractive errors at 12 months after PRK were -0.3 +/- 1.6D in group A, and -1.5 +/- 2.1D in group B. The percent of achieved correction within +/- 1.0D were 70.8% in group A, and 46.7% in group B 12 months after surgery. The epithelium healed by three days and there were no corneal erosions. Corneal haze (Grade 2 or more) was seen in 9.0% in group A and 36.4% in group B at 12 months after PRK. A planned double-pass PRK is a promising approach to correct high myopia (up to -10.50D), but long-term follow up will be required.