Surgically induced astigmatism after phacoemulsification with and without correction for posture-related ocular cyclotorsion. Randomized controlled study

Purpose: To report the impact of posture-related ocular cyclotorsion on one surgeon's surgically induced astigmatism (SIA) results and the variance in SIA. Setting: Institute of Eye Surgery, Whitfield Clinic, Waterford, Ireland. Methods: This prospective randomized controlled study included eyes that had phacoemulsification with intraocular lens implantation. Eyes were randomly assigned to have (intervention group) or not have (control group) correction for posture-related ocular cyclotorsion. In the intervention group, the clear corneal incision was placed precisely at the 120-degree meridian with instruments designed to correct posture-related ocular cyclotorsion. In the control group, the surgeon endeavored to place the incision at the 120-degree meridian, but without markings. Results: The intervention group comprised 41 eyes and the control group, 61 eyes. The mean absolute SIA was 0.74 diopters (D) in the intervention group and 0.78 D in the control group; the difference between groups was not statistically significant (P>.5, unpaired 2-tailed Student t test). The variance in SIA was 0.29 D² and 0.31 D², respectively; the difference between groups was not statistically significant (P>.5, unpaired F test). Conclusions: Attempts to correct for posture-related ocular cyclotorsion did not influence SIA or its variance in a single-surgeon series. These results should be interpreted with full appreciation of the limitations of currently available techniques to correct for posture-related ocular cyclotorsion in the clinical setting. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.