Impact of epithelial removal techniques on low contrast acuity after photorefractive keratectomy: A prospective randomized study.

SIGNIFICANCE: This study reveals the advantage, in terms of quality of vision, of using mechanical debridement with rotating brushes versus chemical debridement, which has significant, broad practical applications for refractive surgeons, optometrists and patients. These findings may aid all parties in decision-making, as well as influence financial planning and time to full visual recovery.

PURPOSE: To compare the effect of the rotating brush and ethanol de-epithelization techniques on visual contrast sensitivity after photorefractive keratectomy (PRK).

METHODS

This was a prospective, randomized study including myopic patients who underwent bilateral PRK, with one eye de-epithelialized with a rotating brush and the other with 20% ethanol, followed by wavefront-optimized laser ablation. Preoperative, 3- and 12-month postoperative thresholds of low contrast visual acuity were found to be 6%, 12.5%, and 25%, respectively. A nonparametric Friedman and post hoc test was used to compare measurements between the eyes and within-group differences.

RESULTS

The study included 96 eyes. Related-sample Friedman's test showed significant statistical difference (P=0.004, P<0.001, P<0.001, respectively) between all six groups (ethanol and brush groups measured at baseline, 3, and 12 months postoperatively), rejecting the null hypothesis of equal variances. In post hoc analysis 12 months postoperatively between ethanol and brush groups at the 6% threshold, no statistically significant difference was observed; at the 12.5% threshold, a statistically significant difference was seen (P=0.013), and at the 25% threshold, a statistically significant difference was observed (P=0.046). A significant difference was observed in the brush group between 3 and 12 months whereas a statistically significant difference was barely achieved in the ethanol group. A significant difference was observed in both groups between 3 and 12 months (P<0.001).

CONCLUSION

Both corneal epithelial debridement techniques are safe and effective methods for epithelial removal. Nevertheless, in our study, the mechanical debridement technique showed slightly better results in terms of visual contrast sensitivity during the 12-month postoperative follow-up period.