Course of subepithelial corneal haze over 18 months after photorefractive keratectomy for myopia [corrected]

This study of 285 myopic eyes treated with photorefractive keratectomy (PRK), with a maximum follow up of 18 months, was designed to analyze the clinical subepithelial significance of corneal haze after excimer laser PRK. The treatment parameters included an ablation zone diameter from 3.6 to 5 mm, ablation rate from 0.22 to 0.25 micron pulse, fluence of 180 mJ/cm2, and frequency of 10 Hz. All patients used a standard topical corticosteroid regimen. A statistical analysis of the subjective haze grading showed a maximum at 3 months (mean grading, 1.03) and a decrease to 0.38 at 18 months. Haze is statistically greater with higher amounts of treatment (p = .003 between 2.00 D and 3.00 D groups, p = .0002 between 2.00 D and 6.00 D groups). In males (p = .0004), and in ablations less than 4.5 mm diameter (p = .0002) but no difference was found related to age. The overall frequency of clinically significant haze was 11.5% with a mean age of 35.1 years and a mean attempted correction of -5.71 D. This frequency increased to 24% in the 6.20 D to 9.90 D group and 38.6% in the 4.4 mm and less group, and it decreased to 8.6% in the 1.00 D to 6.00 D group and 6.6% in the 4.5 and 5 mm group. All patients with significant haze gave a history of discontinued use of corticosteroids. We suggest there exists a significant haze risk group in which the absence of steroid or discontinuation of corticosteroids will lead to significant haze.