Structural and histologic eyelid changes associated with 6 months of topical bimatoprost in the rabbit

Purpose: To determine the periorbital effects of daily 0.03% bimatoprost in New Zealand white (NZW) rabbits. Materials and Methods: NZW rabbits were treated with daily 0.03% bimatoprost, artificial tears, or left untreated. Following 3 and 6 months of treatment, eyelid measurements were obtained for both upper and lower eyelid distraction, as well as canthus-to-canthus measurements. Once complete, subjects were humanely euthanized and eyelid tissue was utilized for histology. Hematoxylin and eosin staining, along with Verhoeff Van Giesen staining was performed on paraffin-embedded sections. Tissue was also stained with mActin antibodies as a marker for fibroblast activity. Results: Daily, topical 0.03% bimatoprost induced eyelid tightening and shortening the NZW rabbit. These findings were most striking at the 6-month timepoint, suggesting a temporal component to these induced changes. Histologically, eyelid tissue demonstrated thinning in bimatoprost-treated eyelids compared with those receiving artificial tears. Slightly increased mActin and Verhoeff Van Giesen staining was observed, suggesting increased fibroblast activity and elastin production in prostaglandin analogs-treated eyelids. Conclusions: These findings suggest that eyelid tissue thins and tightens over time, following daily administration of 0.03% bimatoprost in the NZW rabbit. These findings are similar to what has been observed in human patients.