July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Measurement of the optical quality of contact lens materials with dehydration
Author Affiliations & Notes
  • soheila boojari
    university of arizona, Phoenix, Arizona, United States
  • Jim Schwiegerling
    university of arizona, Phoenix, Arizona, United States
  • Footnotes
    Commercial Relationships   soheila boojari, Alcon Laboratories (F); Jim Schwiegerling, Alcon Laboratories (F)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 6346. doi:
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      soheila boojari, Jim Schwiegerling; Measurement of the optical quality of contact lens materials with dehydration. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6346.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : A wide variety of different contact lens materials are available, each having different dehydration characteristics. Extended exposure of these materials to the ambient air leads to breakup of lens surface moisture and degradation of image quality due to irregularity of the surface moisture and scatter from the surface roughness of the underlying bulk material. The purpose is to develop an objective means for measuring the optical performance of different contact lens materials while dehydrating to provide insight into their on-eye performance of insufficient tear film stability.

Methods : Two generations of a system for objectively measuring the optical performance of dehydrating contact lens materials have been developed. In the first generation system, an artificial eye consisting of an achromatic doublet with one surface having a radius of curvature similar to that of the cornea is mounted in a 3D printed “sclera” so as to provide a smooth transition between the lens and sclera. After placing contact lenses onto its surface, a camera is used to view an ETDRS chart at optical infinity through the eye model assembly. Following alignment and hydration, a two-minute video clip of the eyechart viewed through the system is recorded while the contact lens is exposed to the ambient air. Letter visibility and contrast over time are assessed to determine the optical performance with time.

Results : The optical quality demonstrates two distinct types of progression. The first type of progression has the letter targets steadily blur and lose contrast. The optical quality will ultimately reach a minimum and then begin to improve to varying degrees. This effect is interpreted as the underlying contact lens surface being smooth and image quality is restored once the lens surface moisture has fully evaporated.The second type of progression has the letter targets blur and lose contrast and then remain in that state. This is interpreted as the underlying contact lens surface being rough once the lens surface moisture is fully evaporated. The types of progression and the rates of degradation are strongly contact lens material dependent.

Conclusions : The system provides a means for measuring the optical quality through a contact lens and the degradation of this quality as a function of lens surface moisture breakup. The Placido system enables a correlation between the optical quality and the surface film dynamics.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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