Measurement of static and dynamic cyclotorsion during corneal refractive surgery using SCHWIND AMARIS

Abstract

Objective To investigate the direction and the amount of static cyclotorsion (SCC) and dynamic cyclotorsion (DCC) in ametropic patients during corneal refractive surgery.Methods Two hundred eighty-one eyes of 144 patients who had undergone SCHWIND AMARIS corneal refractive surgery from May 2013 to July 2013 were involved in the study.Ablation was performed using the SCHWIND AMARIS (Version:500).The magnitudes of static and dynamic cyclotorsion were recorded in the supine position during the operation by the SCHWIND AMARIS excimer laser system.SCC and DCC were compared by gender,eye,surgical technique and preoperative spherical equivalent.Enumeration data were compared with a x2 test and measurement data with an intergroup t test.Results Prevalence rates were 66.55％ for SCC,and the mean SCC value was 3.34°±2.57°(range 0° to 12°).Prevalence rates for Femto-LASIK and Trans PRK were 57.44％ and 87.21％,respectively.The difference was statistically significant (x2=23.76,P＜0.01).Sixty percent of the successful SCC right eyes and 50％ of the successful SCC left eyes with counterclockwise rotation.The mean DCC amplitude was 2.30°±1.42°(0.00°～7.80°).The mean DCC amplitude was 2.05°±1.26°in eyes treated with Femto-LASIK and 2.88°±1.59° in eyes treated with Trans PRK.The difference was statistically significant (t=4.33,P＜0.01).The mean DCC amplitude was 2.51°±1.51° in eyes with a preoperative spherical equivalent of ≥-5.00 D and 2.00°±1.23° in eyes with a preoperative spherical equivalent of ＜-5.00 D.The difference was statistically significant (t=3.07,P＜0.01).Conclusion Significant cyclotorsion occurs during corneal refractive surgery.The SCHWIND AMARIS excimer laser system is a useful tool to measure static and dynamic cyclotorsion precisely and to compensate effectively. Key words: Refractive surgical procedure; Cyclotorsion; Static cyclotorsion; Dynamic cyclotorsion