Effect of nitrogen flow on recovery of vision after excimer laser photorefractive keratectomy without nitrogen flow.

Abstract

BACKGROUND Excimer laser (VISX) photorefractive keratectomy was performed using nitrogen flowing through the ocular fixation ring. It was felt that eliminating nitrogen flow may provide faster early visual rehabilitation. METHODS Two groups of 50 consecutive eyes underwent photorefractive keratectomy with (N2 flow) and without (no N2 flow) nitrogen flow, and were evaluated at 1 month postoperatively. RESULTS There were more under- or overcorrections exceeding 1.00 diopter (D) in the N2 flow than in the no N2 flow groups. Eighteen eyes in the N2 flow and 11 in no N2 flow groups saw 20/50 or less, without correction. Fourteen eyes in the N2 flow and nine eyes in the no N2 flow groups lost two or more lines of best spectacle-corrected visual acuity. Four eyes in the N2 flow and none in the no N2 flow groups increased more than 1.00 D of astigmatism. CONCLUSION The elimination of nitrogen flow in photorefractive keratectomy performed with the VISX laser appears to improve visual results in the early postoperative period.