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Ryan Todd Wallace, Mitchell A. Kirby, Wyatt Messenger, Matthew O'Donnell, Ruikang K Wang, Tueng T Shen; Transmittance of UV-A light during corneal cross-linking. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3572.
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© ARVO (1962-2015); The Authors (2016-present)
Corneal cross linking (CXL) involves riboflavin diffusion, theoretically shielding the contents of the eye from excess UV light exposure. The purpose of this study was to measure the amount of UV light passing through ex-vivo human corneas subject to standard CXL Dresden protocol. The amount of UV light transmitted through the cornea during the procedure may be used to estimate irradiation on various ocular structures.
Six human cornea stored in Optisol were secured through the University of Utah Lion’s Eye Bank in Murray, Utah. Each cornea was secured to a modified artificial chamber to measure UV irradiation passing through tissue subject to the standard Dresden protocol using a UV-photosensitive sensor placed approximately 10 mm from the corneal tissue in air.A 0.146% riboflavin solution in 20% dextran (Rf/dextran) was prepared using 500,000 weight dextran in isotonic saline. Every 2 minutes for 30 minutes, a 50 µL drop of riboflavin solution was placed on the apex of the cornea. Following the 30min initial installation of riboflavin, corneas were exposed to 3 mW/cm2 UV light (365 ± 10 nm) for 30 minutes. Rf/dextran drops were continued every 5 minutes during the 30min UV exposure.
Transmittance prior to Rf/dextran exposure was 53% (1.71 ± .06 mw/cm2). Following the initial 30 min Rf/dextran application, transmittance was measured at 43% (1.22 ± .08 mw/cm2). Following radiation with the application of Rf/dextran every 5 minutes for 60 minutes, transmittance was 26% (0.84 ± .07 mW/cm2). OCT-measured central cornea thickness was 550 ± 84 μm before and 453 ± 72 μm after CXL.
The measured UV transmission following Rf/dextran application can be used to estimate tissue optical properties. Such measurement may be used to explore UV irradiance to better understand potential dangers due to phototoxicity on ocular tissue during early CXL UV exposure.
This is a 2020 ARVO Annual Meeting abstract.
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