The Effects Of Corneal Flap Side-Cut Angle On Flap Stability In Femtosecond Lasik

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

Care-Vision Laser Center in Tel Aviv, Israel.

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.

The following data were extracted from the medical files of patients who met the inclusion\exclusion criteria: age, gender, refractive error, minimal corneal thickness (CT), keratometry, uncorrected and corrected distance visual acuities (UDVA and CDVA).

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% females. Average follow-up period was 35.5 ± 29.9 days. Post-operative flap striae occurred more often in eyes with a 120° angle (3.1% vs. 0.9%, p=0.05). No significant differences existed in epithelial ingrowth, diffuse lamellar keratitis, post-op flap refloat and irrigate procedures, halos, or glare. The 70-degree group outperformed the 120° group, showing 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° group demonstrated higher efficacy and safety indices (1.06 vs. 1.05, p=0.053 for efficacy; 1.07 vs. 1.06, p=0.02 for safety).

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.