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

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

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.

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.

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.