Comparison of Tear Film Stability and Correction for Improvement by Toric Soft Contact Lens Materials

Abstract

Purpose : The Purpose of this study was to compare the degree of axial rotation and NIBUT of toric soft contact lenses which were three types of different materials and axial stability designs. Methods : The three types of toric soft contact lenses (hereinafter toric SCL) were worn on 19 subjects. One of them was double thin zone design lens (A-lens), the second was ASD lens (B-lens), and the third was prism ballast design lens (C-lens). Subjects were wearing the toric SCL to find out NIBUT for tear film stability and degree of the rotation for axial stability. All examinations were conducted after wearing SCL for two different wearing times such as 20 minutes (short time) and 8 hours (long time). Results : The “A-lens” corrected visual acuity was moderate at the initial wearing, and excellent after long time wearing. The result of NIBUT showed that “B-lens” was the best in initial wearing(p 0.050). The best axial stability was “A-lens” in the initial wearing(p 0.050). Conclusion : While the “A-lens” was best corrected visual acuity, it was worn for a long time, reducing tear film stability and surface wetting tendency. “B-lens” had better tear film stability and axial stability than the others in the early stage of lens wearing due to wet treatment on the surface and ASD design. In the C-lens with silicone hydrogel material, the corrected visual acuity was good, but the tear film stability and axial stability the poorest. It is considered that the great improvement for a method of surface treatment of silicone hydrogel is necessary.