Analysis of rotation evaluation with toric soft contact lenses

Abstract

Objective The purpose of this study was to analyze the results of factors related to lens stability, and the correlations among them. Methods It was a noninterventional,observational study. Thirty-two subjects were enrolled in this study. Both eyes wore Lo-Torque frequent replacement toric soft contact lenses. Stability evaluations were done after 20 minutes of wear, including visual acuity with the contact lens, lens positioning, activity, rotation direction,rotation degree, rotation stability, and nasal and temporal rotation recovery speed. One eye of each subject was randomly selected. The correlations between the parameters were evaluated with SPSS 13.0statistical analysis software. Results The percent of temporal rotation was 59%, with a mean degree of (10.56±7.77)°. There was a negative correlation between nasal rotation recovery speed and overall assessment (r=-0.49, P=0.005). For the looser lens, rotation recovery was faster from the nasal side.The degree of rotation was significantly correlated with rotation direction (r=0.48, P=0.006); the amount of rotation to the temporal side was less than to the nasal side. There was a positive correlation between rotation degree and orientation stability (r=0.45, P=0.010), the less the degree of rotation, the better the stability. Conclusion Frequent replacement toric soft lenses rotate easily to the temporal side in the clinic. Attention should be paid to loose fittings and temporal rotation. There are many factors that affect lens stability, including overall assessment and degree of rotation. This study suggests that more attention should be paid to the overall assessment of the degree of rotation when dispensing toric soft contact lenses in the clinic. Key words: Contact lenses,soft,toric ; Rotation; Astigmatism