Photorefractive keratectomy in flat, normal, and steep corneas

Purpose:To compare photorefractive keratectomy (PRK) outcomes in patients with different corneal steepness.Setting:Care-Vision Laser Center, Tel-Aviv, Israel.Design:Retrospective comparative chart review.Methods:Patients included in this study underwent wavefront optimized myopic PRK between January 2013 and December 2019. Patients were divided into 3 groups based on the steepness of the cornea (steep keratometry) (flat: <42 diopters [D], normal: 42 to 46 D and steep: >46 D). One to one matching was performed to verify that baseline parameters (age, preoperative visual acuity and refractive error) were similar between groups. Primary outcome measures were: postoperative corrected/uncorrected distance visual acuity (CDVA/UDVA), efficacy index (postoperative UDVA/preoperative CDVA), safety index (postoperative CDVA/preoperative CDVA), spherical equivalence (SEQ) and cylinder.Results:After matching, 650 eyes were included in each group, which were similar in baseline parameters. There were no significant postoperative differences between flat, normal, and steep corneas in terms of safety index (1.02 vs 1.03 vs 1.03, P =.28), efficacy index (1.01 vs 1.01 vs 1.02, P =.57), logMAR CDVA (0.01 vs 0.02 vs 0.01, P =.76), logMAR UDVA (0.02 vs 0.03 vs 0.02, P =.68), %SEQ within 0.50 D (73.9% vs 74.2% vs 74.6%, P =.95) or 1.00 D of target (91.9% vs 92.5% vs 92.2%, P =.92), %cylinder within 0.50 D (82.8% vs 82.2% vs 81.4%, P =.81) or 1.00 D of target (96.9% vs 97.1% vs 97.2%, P =.95).Conclusions:No significant differences were found between flat, normal and steep corneas following wavefront-optimized myopic PRK. Thus, this procedure may be safely and effectively performed in both flat and steep corneas.