Intraocular straylight after thin-flap LASIK with a femtosecond laser versus a mechanical microkeratome

Abstract

Purpose: To investigate characteristics of straylight before and after thin-flap LASIK performed with femtosecond laser versus with mechanical microkeratome and assess changes at 1 day, 1 week, 1 month, 6 months, and 1 year postoperatively.

Methods: One hundred twenty-eight consecutive eyes from 66 patients were included in this prospective study. Sixty-one eyes of 31 patients had thin-flap LASIK with femtosecond laser. In addition, 67 eyes from 35 patients underwent thin-flap LASIK with mechanical microkeratome were included for comparison. Following flap creation, all eyes were ablated using the VIXS S4 excimer laser system (Visx USA, Inc., Santa Clara, CA). Straylight values were measured using the C-Quant straylight meter (Oculus Optikgeräte GmbH, Wetzlar, Germany) preoperatively and 1 day, 1 week, 1 month, 6 months and 1 year postoperatively.

Results: Preoperatively, the mean straylight values were 0.93 ± 0.11. After femtosecond laser-assisted thin-flap LASIK, the values were 1.00 ± 0.11, 0.98 ± 0.10, and 0.99 ± 0.12 at 1 day, 1 week, and 1 month, respectively, and significantly increased (F = 7.62, P > .0001) compared to preoperative values. However, these values decreased and returned to preoperative levels at 6 months and 1 year postoperatively (0.92 ± 0.09 and 0.89 ± 0.13, respectively; P > .05). The postoperative-preoperative increases in straylight were reduced in the femtosecond laser group compared to the mechanical microkeratome group (0.05 ± 0.13 vs 0.10 ± 0.13 at 1 month postoperatively; P < .05). This difference was statistically significant at 1 month postoperatively (P = .04). A negative significant correlation was also found between preoperative straylight values and postoperative-preoperative increases.

Conclusions: Straylight increased significantly in the early stages after femtosecond laser-assisted thin-flap LASIK. However, these values improved over time and gradually returned to preoperative levels, which may be related to the progression of corneal healing.