Effects of torsional movements in refractive procedures.

UNLABELLED: Using PubMed and our internal database, we extensively reviewed the literature on the history of measurement of torsional movements of the eye from 1963 to the present, focusing specifically on the implications of torsional measurement and compensation in corneal refractive and ocular surgery. Mean cyclotorsional movements observed in refractive surgery procedures have been reported to be around 3 degrees, which can be well controlled by the currently used technology. Torsional movements affect aberrations with a vectorial component (astigmatic procedures) more adversely. Currently available eye-registration technology provides an accuracy of ±1.5 degrees. The vectorial components of residual aberrations can be minimized by intentionally underplanning the refractive treatments. The gaps in our knowledge limit the precision in current surgical procedures due to imperfect cyclotorsion compensation. This review summarizes about the explored aspects of torsional movements in surgical applications and raises questions about the unexplored implications. FINANCIAL DISCLOSURE: Dr. Arba Mosquera and Mr. Verma are employees of Schwind eye-tech-solutions GmbH and Co. KG.