Applied Forces Changed Myopia Lens Optical Performance but Not Retinal Image Quality Tested Using a Newly Designed Digital Colmascope

BACKGROUND: The aim of this study was to investigate the effects of applied forces generated by a rim screw on the optical performance of mounted myopia lenses. The residual refractive error and retinal image quality of the corrected eyes were also investigated. METHODS: For 120 lenses, internal lens stress was measured using a newly designed digital strain viewer (colmascope). Sixty myopic adults (120 eyes) were recruited. The effects of internal lens stress on residual refraction and retinal image quality were evaluated using OPD Scan III. The results were compared between loose and tight mounting and between the right and left eyes. RESULTS: Significant differences were observed among nine lens zones in both the right and left lenses, regardless of the mounting state (P < 0.001). The differences were mainly derived from the five vertically arranged zones (P < 0.05). Significant differences in internal lens stress were observed between the right and left lenses (P < 0.05). No significant differences in central residual refractive error and retinal image quality of the corrected eyes were found between the loose- and tight-mounted lenses. CONCLUSION: The applied forces generated by the rim screw changed the peripheral optical performance of the mounted myopia lenses but exerted only negligible impacts on the central residual refractive error and visual image quality.