Factors Associated With Ocular Cyclotorsion Detected by High-Speed Dual-Detection Eye Tracker During Single-Step Transepithelial Photorefractive Keratectomy.

Purpose: To determine demographic, surgical, and preoperative visual factors affecting the level of static and dynamic cyclotorsion (SC and DC) in eyes undergoing single-step transepithelial photorefractive keratectomy (TransPRK).
Methods: In this cross-sectional study, 386 patients with different types of refractive errors scheduled for single-step TransPRK were enrolled. A comprehensive profile of personal, optic, and visual characteristics of patients as surgical parameters were collected. Statistical modeling was used to explore correlates of SC and DC before and during the refractive procedure, respectively.
Results: There was no difference in various indices of SC and DC between right and left eyes. Lower age (beta = -0.20), uncorrected (beta = -0.99) and corrected (beta = -0.72) visual acuities, and keratometry (beta = -0.09) were significantly associated with higher ranges of DC during the laser ablation procedure. Worse mesopic contrast sensitivity (beta = 0.24) and higher (beta = 0.002, left eyes) or lower (beta = -0.002, right eyes) kappa locus also showed significant associations with a higher range of DC. In cases of SC before the procedure, amount (beta = 0.46) and axis (beta = -0.003) of the astigmatism demonstrated notable associations.
Conclusions: Through comprehensive modeling, age, visual axis indices, visual acuity, and contrast sensitivity were found to be the main factors significantly associated with dynamic ocular globe cyclotorsions during single-step TransPRK. This could help identify eyes at higher risk of cyclotorsion and its potential complications in refractive surgery. [J Refract Surg. 2018;34(11):736-744.].
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