Influence of patient race on the autcome of photorefractive keratectomy for myopia correction

ABSTRACT

Purpose: To examine the effect of patient race on clinicai outcomes following excimer kaer surgery for myopia and myopic astigmatism. Methods: A total of 116 eyes from Caucasian patients,16 eyes from Asian patients and 16 eyes from Hispanic patients who underwent PRK were evaluated retrospectively. PRK procedures were performed by the same surgeon using a 193 mm argon- fluoride excimer laser (VISX) with 160 mJ/ cmz fluence and a 6.5 Hz repetition rate at the Doheny Eye Institute. During 6 months of follow-up, changes in the uncorrected visual acuity (UCVA), refraction and spectacle-corrected visual acuity (SCVA) were evaluated. Pairwise comparisons between races were performed for age, sphere and cylinder using independent sample t tests, while UCVA and SCVA were compared using Fisher' s exact tests. The accepted level of significance for ali tests was a=0.05/3 =0.0167. Results: The only differences found were between the Asian versus Caucasian groups related to the spectacle-corrected visual acuity of 20/15 (p=0.01) and in the Asian versus Hispanic groups related to the mean cylinder (p=0.04) at 3 months postoperatively. The comparison of the mean cylinder showed a statistically significam difference between the Asian versus Hispanic groups at 6 months posto-peratively (p=0.04). After 6 months, 72.7 percent of the eyes in the Asian group, 85.7 percent of the eyes in the Hispanic group and 87.1 percent of the eyes in the Caucasian group had uncorrected visual acuity of 20/40 or better and the mean sphere andcylinder(ñSD) were-0.55 (ñ0.88) and0.97 (ñ0.79);-0.75 (ñ 1.24) and 0.40 (ñ 0.45); -1.21(ñ 2.55) and 0.75 (ñ 0.89), respectively. Conclusion: In this study, there were no statistically significant differences between the three race groups related to the final visual outcome following photorefractive keratectomy. These prefminary results suggest that the clinicai outcomes of PRK are not significantly affected by patient race. Larger populations and longer-term studies are needed to definitely determine whether racial differences exist.