Analysis of Bimatoprost-Induced changes on Rabbits eyelash Follicle: Clinical and Electron microscopic study

OBJECTIVE: To analyze ultrastructural changes of rabbits' eyelash follicles treated with bimatoprost eye drops to increase our knowledge of how this drug works. METHODS: The study included 15 clinically healthy male rabbits. All rabbits were treated with bimatoprost 0.03% daily for 4 weeks with one drop of the topical eye drops applied to the conjunctival fornix of the right eyes; left eyes were used as controls. Eyelash lengths were measured before and after treatment. The eyelid of each animal was dissected for light and electron microscopic analysis. RESULTS: Both control and treated rabbit eyes matched regarding eyelash length before treatment (9.80±0.388mm vs 9.88±0.24mm) (P=0.108). There was a significant increase in eyelash length between control (9.75±0.33 mm) and treated rabbit eyes (11.60±0.46 mm) (P=0.369). Light and electron microscopy revealed, bimatoprost treated eyes had thick epidermis. The dermis contained two hairs growing out of the same hair follicle. Heavily keratinized Henle’s layer, the cortical cells (Cx) have prominent nucleolus and cytoplasm is studded with melanin granules. CONCLUSION: Bimatoprost-induced eyelash changes were not restricted to increased eyelash length, thickness, and pigmentation but also showed increased number of eyelashes within the same hair follicle which were stronger and could resist pulling from the skin without any evidence of inflammatory cells within the specimens. These changes occurred as early as 1 month of treatment, giving rise to thoughts about the possibility of using bimatoprost eye drops as a prophylaxis against madarosis associated with chemotherapy if it is started 1 month before chemotherapy and continued afterwards, making eyelashes stronger and resistant to falling out.