The Effects of Corneal Flap Side-Cut Angle on Flap Alignment and Postoperative Vision and Refraction in Femtosecond LASIK.

Abstract

Purpose: To assess the impact of two side-cut angle profiles on surgical outcomes following femtosecond laser in situ keratomileusis (FS-LASIK).

Setting: Care-Vision Laser Center, Tel-Aviv, Israel.

Design: Retrospective comparative chart review.

Methods: This retrospective cohort study included patients who underwent wavefront-optimized femtosecond LASIK surgery between 2023 and 2024, with complete medical records. Eyes with a 70-degree side-cut angle were matched with those with a 120-degree angle. Monovision surgeries and any intraoperative complications were excluded from the analysis.

Results: A total of 318 pairs of matched eyes were included in the study. The mean age of participants was 26.9 ± 7.2 years, ranging from 18 to 54 years, with 54% being female. The average follow-up period was 35.5 ± 29.9 days. Post-operative flap striae occurred more often in eyes with a 120-degree angle (3.1% vs. 0.9%, p=0.05). There were no significant differences in epithelial ingrowth, diffuse lamellar keratitis, post-op flap refloat and irrigate procedures, halos, or glare. The 70-degree group outperformed the 120-degree group, showing a statistically significant higher %SEQ within 0.50D (94.0% vs. 92.1%) and within 1.00D of the target (100% vs. 99.1%, p=0.003). The 70-degree group demonstrated higher safety index (1.07 vs. 1.06, p=0.02).

Conclusion: Using a 70-degree side-cut angle may reduce the prevalence of post-operative striae, and better SEQ predictions, with no other differences in complications.