Soft contact lens materials are fabricated from polymers that have a relatively lower material rigidity. The flexible soft contact lens materials could reshape itself and deform to a different lens shape after placing on a rigid surface. Besides its flexibility, typically, lens material (such as hydrogel) contains water. The deformed lens shape along with posterior lens liquid films and lens liquid evaporation could further modify its in air optical performances. Thus, it is important to quantitatively study the soft material wavefront aberration correction properties directly in air. In this study, contact lenses were covered on a hard plastic phantom which has a similar surface curvature as the lens posterior surface. Appropriate lens hydration was maintained to minimize evaporation introduced surface deformation. A Shack-Hartmann wavefront measurement system was installed to measure lens-phantom system wavefront aberration in air. Transmission wavefront aberrations with and without covering spherical lenses (on phantom) were measured and the wavefront aberration difference were compared with labeled lens power. For a 0.5D negative lens, measured lens power is -0.53±0.07D and within 4-mm pupil size, higher order aberration RMS is 0.08 µm. Other lens power was also measured with an averaged power error less than 7%. The results indicate the measurement introduces minimized lens surface deformations (due to liquid evaporation) and has precise measurement repeatability. The technology offers a metrology to be potentially used to study lens deformations on different surface curvatures, which potentially provides a guidance for lens on-eye fitting performance investigation.
Minghan Chen, "Employing wavefront detection system to study soft contact lens in air deformation properties (Conference Presentation)," Proc. SPIE 10486, Design and Quality for Biomedical Technologies XI, 104860C (Presented at SPIE BiOS: January 27, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2286949.5751457676001.
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