Differences in Cyclotorsion Compensation Between Low, Medium, and Large Angles in Myopic PRK: Visual and Refractive Results

Purpose: To evaluate the differences in myopic photorefractive keratectomy (PRK) outcomes between small, medium, and large cyclorotational angle degrees. Methods: This retrospective comparative study was conducted at Care Vision Laser Center, Tel Aviv, Israel. The study included consecutive patients who underwent myopic PRK between 2012 and 2023. Patients were divided into three groups according to their cyclorotation angle magnitude. A comparison of baseline and intraoperative parameters was performed. Refractive and visual outcomes were assessed and an Alpins vector analysis was performed. Multiple linear regression was performed to identify the effect of potential confounders. Results: A total of 17,214 eyes from 10,859 patients were analyzed (mean age: 25.9 ± 7.5 years, 55.7% male and 44.3% female). The large cyclorotation angle group exhibited statistically but not clinically significant lower corrected (CDVA) and uncorrected (UDVA) distance visual acuity at final follow-up compared to the other groups. However, no significant differences were observed in refractive outcomes, safety and efficacy indexes, or Alpins vector analysis. On regression analysis, preoperative CDVA was the only significant predictor of final CDVA (β = 0.633, P < .01). Although cylinder magnitude did not vary between the groups at baseline, in subgroup analysis by stratification into higher cylinders, efficacy was significantly lower in the small compared to the medium cyclorotation group, but the result was clinically negligible. Conclusions: Cyclorotation angles up to 10 degrees had no clinically significant impact on PRK refractive outcomes. These findings suggest that modern excimer laser systems effectively compensate for cyclorotation within this range, ensuring precise treatment delivery.