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William Michael Berkowski, Daniel J Gibson, Laura Proietto, David David Whitley, Gregory S Schultz, Caryn Plummer; Assessment of topical therapies for improving optical clarity following stromal wounding in a novel ex vivo canine cornea model.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5714.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the effect of two topical anti-fibrotic medications, suberanilohydroxamic acid (SAHA) and 5-methyl-1-phenyl-2[1H]-pyridone (pirfenidone), on the degree of corneal haze following stromal wounding in the ex vivo canine cornea.
Corneoscleral rims were harvested from clinically normal globes of dogs euthanized for reasons unrelated to ophthalmic disease (n=24 corneas). A 200 μm deep stromal wound was created in each axial cornea with an excimer laser. Tissues were then cultured in a buffered DMEM / Ham's F-12 based medium, kept on a nutating plate, and maintained at 37°C and 5% CO2. The control group (n=8) contained wounded, untreated corneas. Treatment group 1 (n=8) received 6.6 µg/mL (25 μM) SAHA topically every 6 hours for 21 days. Treatment group 2 (n=8) received 200 μg/mL (1.08 mM) pirfenidone topically every 6 hours for 21 days. Each cornea was stained with fluorescein dye and photographed every 6 hours until full epithelialization occurred. Wound area (mm2) was calculated for each cornea to assess epithelialization rate. All corneas were also photographed at 0, 7, 14, and 21 days to record changes in optical clarity (haze). Day-21 images of each cornea were analyzed to determine the difference in pixel intensity values between wounded (haze) and unwounded (non-haze) regions. A threshold filter was also used to isolate haze pixels and calculate haze surface area (mm2) for each day-21 cornea.
The mean epithelialization time was 52 hours in the control group, 45 hours in the SAHA group, and 43.5 hours in the pirfenidone group. There was no significant difference in epithelialization time between the control and treatment groups (p = 0.4). The median difference in pixel intensity between haze and non-haze areas was 22 in the control group, 6 in the SAHA group, and 8 in the pirfenidone group, showing a significant difference between the control group and each treatment group (p < 0.01). The median haze surface area was 13.0 mm2 in the control group, 5.6 mm2 in the SAHA group, and 5.9 mm2 in the pirfenidone group, which is significant (p < 0.01).
Stromal-wounded ex vivo canine corneas exhibited significantly greater optical clarity when treated with 25 μM SAHA and 1.08 mM pirfenidone than when left untreated at 21 days. There was no significant difference in epithelialization rate between groups.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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