Assessment of Topical Therapies for Improving the Optical Clarity Following Stromal Wounding in a Novel Ex Vivo Canine Cornea Model

Abstract

PURPOSE. To evaluate the effect of topical suberanilohydroxamic acid (SAHA) and 5-methyl-1phenyl-2[1H]-pyridone (pirfenidone) on the degree of corneal haze in the stromal wounded ex vivo canine cornea. METHODS. Twenty-four corneoscleral rims from normal dogs were uniformly wounded with an excimer laser and placed into culture medium with an air-liquid interface. The control group (n ¼ 8) contained placebo-treated corneas. Treatment group 1 (n ¼ 8) received SAHA topically every 6 hours. Treatment group 2 (n ¼ 8) received pirfenidone topically every 6 hours. Each cornea was fluorescein stained and macrophotographed every 6 hours to assess epithelialization rate. All corneas were also macrophotographed weekly to assess optical clarity (haze). Images were analyzed for differences in pixel intensity between wounded (haze) and unwounded (nonhaze) regions, and haze surface area for each cornea was calculated. RESULTS. The mean epithelialization time was 47.25 hours in the control group, 45.00 hours in the SAHA group, and 43.50 hours in the pirfenidone group, revealing no significant difference (P ¼ 0.368). The median difference in pixel intensity between haze and nonhaze areas was 21.5 in the control group, 8.0 in the SAHA group, and 8.0 in the pirfenidone group, which is significant (P < 0.01). The median haze surface area was 12.96 mm 2 in the control group, 5.70 mm 2 in the SAHA group, and 5.92 mm 2 in the pirfenidone group, which is significant (P < 0.01). CONCLUSIONS. Stromal-wounded ex vivo canine corneas exhibited greater optical clarity when treated with SAHA and pirfenidone than when placebo treated at 21 days. There was no significant difference in epithelialization rate between groups. Corneal contour was correlated with geographic haze distribution.

Dexmedetomidine and Tear Production: Evaluation in Dogs as Spontaneous Model for Ocular Surface Disorders

“…The closer resemblances in ocular physiology between dogs and humans can justify the integration of companion dogs into preclinical studies rather than traditional laboratory animals such as rabbits, mice and rats, as reported in the literature [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59].…”

An eye on the dog as the scientist's best friend for translational research in ophthalmology: Focus on the ocular surface

“…The availability of such a model presents a clear opportunity for translational research (i.e., intact innervation, tear film, blood supply), although experimentally induced corneal wounding (at risk of secondary infection) and subsequent corneal scar in dogs represent potential ethical challenges. As an alternative, other authors have established ex vivo canine corneal cultures that can be used to model wound healing and assess antifibrotic compounds, [316][317][318] or better understand the pathophysiology of herpesvirus in a virus-natural-host environment 319 ; in that study, the authors established an air-liquid canine corneal organ culture model to study acute herpetic keratitis, showing important similarities in the response to CHV-1 to what has been described for HSV-1. 319…”

Interleukin‐6 and lactate dehydrogenase expression in a novel ex vivo rocking model of equine corneal epithelial wound healing

“…Ex vivo corneal wound healing models are becoming popular in recent years, as they maintain the dynamic, complex, physiologic events of the in vivo model, while decreasing the need for live animals 19,20,22,24 . In this study, we established an ex vivo model of equine corneal wound healing while demonstrating its physiologic relevance.…”

“…The inherent challenge comes in the desire to learn more about these involved processes without either harming healthy animals in vivo or struggling with physiologic relevance and clinical applicability with in vitro models. The ex vivo corneal model has been developed in other species, 19–22 and represents a logical steppingstone between the equine in vitro ocular benchtop models and the in vivo studies, all while providing physiologically based clinically applicable conclusions 23 . Effective, species‐specific, reproducible models of corneal wound healing are of paramount importance.…”