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Pete Kollbaum, D Robert Iskander, Ryan McGiffen, Meredith Jansen; OPTICAL PATH LENGTH QUANTIFICATION OF SOFT CONTACT LENS PARAMETER CHANGES DURING DEHYDRATION. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5463.
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© ARVO (1962-2015); The Authors (2016-present)
As a soft contact lens (SCL) dehydrates many optical and physical parameters of the lens may change, having the potential to impact vision and lens fit. The purpose of this study was to investigate the feasibility of a novel methodology to quantify dehydration-related SCL shape changes.
High resolution, ex-vivo, Shack-Hartmann wavefront technology was utilized to capture the real-time relative changes in optical path length (10mm analysis diameter), which occurred as lenses dehydrated for periods up to 5.5 minutes. Lenses were positioned on both a plane glass plate and a model eye, which approximated the cornea shape. Optical path length data was used to develop a computational model of the underlying parameter changes.
High-resolution retro-illumination and axial imaging demonstrate areas of lens dehydration and measureable lens surface shape, thickness, and diameter changes, which correlate with the observed optical path length changes. Although the changes vary with lens material, nominal thickness, and power (-9 D to +5 D in 2 D steps), optical path length changes of up to 12 microns may occur for some lenses for short-term air exposures of under 1-2 minutes.
The methodology described appears feasible in describing and quantifying SCL dehydration-related changes. Lenses of different material properties dehydrate differently.
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