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O.-T. Lee, J. M. Stewart; Effects of Ultraviolet-A/Riboflavin Derived Modifications on Corneal Permeability in a Live Rabbit Model. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4978.
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© ARVO (1962-2015); The Authors (2016-present)
To test the hypothesis that Ultraviolet-A (UVA) derived corneal cross-linking decreases drug delivery in an In Vivo and corneal permeability in an Ex Vivo Rabbit Model .
New Zealand White Rabbits were used in the study. Eyes were divided among three groups: 1) Untreated (control), 2) Untreated but with their epithelium mechanically removed. 3) Treated with riboflavin and UVA and epithelium mechanically removed. Beginning 30 minutes before irradiation, group 3 samples were treated with hypotonic 0.1% riboflavin solution administered onto the debrided cornea and continued every 5 minutes until the end of the irradiation period. These corneas were irradiated with UVA light for 30 minutes at a distance of 35 cm (irradiance, 2 mW/cm2) from the corneal surface by using a customed built UVA emitter ( = 370 nm). Sufficient time was allowed for epithelium wound healing and cornea edema drainage. Topical administration of 100 ug of pilocarpine was then applied and pupil constriction over a 30 minute period was measured with a pupilometer. The rabbits were then sacrificed and their corneas were removed and mounted onto a two-chamber diffusion apparatus to determine permeability. Permeability across the tissue, characterized by means of a permeability coefficient, was measured by using fluorescence spectrometry to determine the diffusion of sodium fluorescein.
In control and scraped only eyes, topical delivery of pilocarpine caused pupil constriction from 7.2 mm to 3.8 mm and 3.5 mm respectively. In UVA treated eyes, pupil constriction from 7.5 mm to 4.5mm was observed with slower kinetics. Corneal tissue crosslinked by the UVA treatment resulted in decreased permeability (2.26e-7 ± 9.13e-8 cm/seccompared to control tissues (3.89 e-7 ± 4.79e-8 cm/sec). The decrease was statistically significant (p < 0.05).
Treatment with UVA light decreases the permeability of solute across the rabbit cornea in both our In Vivo and Ex Vivo models. This study shows that UVA derived cross-linking has a significant impact on cornea permeability.
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