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H. Liu, C. G. Begley, L. Thibos, K. Haggerty, R. Chalmers, C. Riley; Visual Performance and Optical Quality Among Contact Lens Wearers. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5416.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously demonstrated simultaneous tracking of objective visual performance and subjective optical quality over a soft contact lens (ARVO-06). We aimed to extend those observations using refined methodologies augmented with retro-illumination (RI) to simultaneously monitor tear film disruption and in vivo lens wetting of the contact lens surface.
A confocal imaging system incorporates a range-defining aperture (RDA) that continuously measures light reflected through the pupil from an infrared laser beam focused on the retina. Light intensity (LI) passing through the RDA is a measure of the fraction of reflected light for which wavefront slope < 6.5 milliradians, which measures dynamic optical quality through changes in light scatter. A monitor, viewed through a beam splitter, displayed letter targets 20/40 in size for which contrast sensitivity (CS) was measured continuously and simultaneously with optical measurements. An infrared light source was used to retro-illuminate the pupil to simultaneously visualize the tear film over the lens surface in the area of pupil. Five hydrogel contact lens wearers were asked to keep one eye open for approximately 35 sec, while CS, LI and R were collected over 3 trials.
LI reduction and CS loss were highly correlated (average r = 0.80±0.53). Ten sec after eye opening trials, CS declined by 40.65%±26.44% and LI was reduced 9.65%±8.26%, and after 35 sec CS declined 68.60%±17.81%. and LI by 28.59%±22.59%. The decline was statistically significant (p<0.001, ANOVA) for both parameters. The distribution of tear breakup over the lens surface as viewed by RI was spatially correlated with the level of LI and CS loss. Centrally located tear breakup appeared to produce a greater loss in LI and CS than peripherally located breakup.
This method allowed simultaneous and dynamic tracking of the deterioration of objective optical quality of the eye and subjective visual performance while viewing surface tear quality and provides a procedure for determining in vivo lens wetting and its effect on vision.This project was supported by a grant from Johnson & Johnson Vision Care, Inc.
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