Effects of topical hyaluronic acid on corneal wound healing in dogs: a pilot study

Abstract

Objective: To investigate the efficacy of topical 0.2% hyaluronic acid in canine corneal ulcers in vivo.

Procedures: Six purpose-bred beagles were randomly assigned into two groups (three dogs/group): group A received experimental product (Optimend^™ , containing 0.2% hyaluronic acid, KineticVet^™ ); group B received control product (Optimend^™ without 0.2% hyaluronic acid and supplemented with carboxymethylcellulose). The clinical scorer was masked to product content and subject assignment. Under sedation and topical anesthesia, 6-mm axial corneal epithelial debridements were performed in the left eye. Wounded corneas received standard ulcer treatment and topical product (group A) or control product (group B) three times a day (TID) until ulcers were healed. Slit-lamp biomicroscopy was performed 6 h after wounding and then every 12 h; findings were graded according to modified McDonald-Shadduck scoring system; extraocular photography was performed after fluorescein stain application at all examination time points. Images were analyzed using NIH image j software to quantify rate of corneal epithelialization. Gelatin zymography was used to analyze matrix metalloproteinase (MMP) 2 and 9 protein expression in tears collected at set time points during the study period.

Results: No statistical differences in clinical ophthalmic examination scores, rate of corneal epithelialization, or MMP2 or MMP9 protein expression were found between groups at any tested time point.

Conclusions: The application of 0.2% hyaluronic acid to standard ulcer medical management is well tolerated. Topical addition of the viscoelastic did not accelerate corneal wound healing compared to a topical control with similar viscosity in this study.

Keywords: artificial tears; canine; carboxymethylcellulose; cornea; hyaluronic acid; matrix metalloproteinase.