A Novel MATLAB-Based Quantification of Microincision Cyclotorsion and Its Impact on Myopic Astigmatism Correction in...

To develop an automated image recognition method for the identification of corneal microincisions in keratorefractive lenticule extraction (KLEx) and assess microincisional cyclotorsion and its impact on postoperative astigmatism correction using vector analysis.

This retrospective study included 92 patients (184 eyes) who underwent KLEx. Postoperative slit-lamp images were analyzed using a custom MATLAB-based program. The cyclotorsion angle and direction of the microincisions were quantified. Vector analysis was used to evaluate postoperative astigmatism correction at one week, one month, and three months. Correlations between cyclotorsion magnitude and preoperative ocular parameters were analyzed, and astigmatic outcomes were compared between low (≤ 4°) and high (> 4°) cyclotorsion groups.

The mean absolute microincision cyclotorsion angle was 4.19° ± 2.92° (range: 0°-12.43°) in right eyes and 4.53° ± 3.36° (range: 0°-13.74°) in left eyes, with no significant interocular difference (p > 0.05). Outward incision cyclotorsion was observed in > 80% of eyes. No significant correlations were found between the cyclotorsion magnitude and preoperative parameters, including age, spherical equivalent, central corneal thickness, keratometry, or Q value (all p > 0.05). At 3 months, there were no significant differences in vector parameters between low and high cyclotorsion groups, though the correction index tended to be slightly lower in the high-cyclotorsion group (0.93° ± 0.32° vs. 1.04° ± 0.40°, p > 0.05).

An automated MATLAB-based method can be used to quantify the cyclotorsional movement of microincisions in KLEx. The magnitude of corneal microincisional cyclotorsion does not appear to have a significant effect on the efficacy of corneal astigmatism correction.