Ocular Cyclorotation and Corneal Axial Misalignment in Femtosecond Laser-Assisted Cataract Surgery

Purpose: To explore ocular cyclorotation and the source of corneal axial misalignment during femtosecond laser-assisted cataract surgery (FLACS).Methods: Forty-five sequential patients (50 eyes) who had undergone FLACS (LenSx Laser System, Alcon Inc) were recruited. We took screenshots from videos of FLACS to analyze ocular cyclorotation and the real angle between primary incision and secondary incision (RAPS). In addition, crystalline lens tilt and theoretic angle between the primary and secondary incisions (TAPS) was also calculated.Results: The mean absolute value of ocular cyclorotation was 8.03 ± 4.48 degrees (0-19.1 degrees). The crystalline lens tilt was 3.30 ± 1.44 degrees (0.93-6.44 degrees). And the mean preoperative uncorrected visual acuity was 0.89 ± 0.50 LogMAR units. Pearson bivariate correlation analysis showed significant positive correlation between ocular cyclorotation with crystalline lens tilt (r = 0.37, p = .008), and ocular cyclorotation negatively correlated with axial length (r = -0.29, p = .038). In addition, the TAPS was 89.78 ± 1.45 degrees, and the RAPS was 85.68 ± 2.04 degrees. The angle error was 4.11 ± 1.28 degrees (p<0.001).Conclusions: Ocular cyclorotation commonly occurred during FLACS. In addition, increased axial length was associated with less ocular cyclorotation and increased crystalline lens tilt was related to more ocular cyclorotation. Importantly, machinery systemic errors during corneal astigmatism correction by arcuate incision in FLACS should be taken into consideration.