Safety of the subconjunctival injection of doxycycline in rabbits.

Purpose: To evaluate the safety of subconjunctival injection of doxycycline in rabbit eyes. Methods: Eight white New Zealand rabbits were selected. Different concentrations of 250 micrograms (μg), 500 μg, 1000 μg, and 2000 μg in 0.1 ml were prepared for subconjunctival injection. Each concentration was injected into the two eyes of each rabbit. For each dose, dextrose was injected in one contralateral eye and the other fellow eye remained non-injected. All rabbits underwent ocular examination in the 1st, 3rd, and 30th day after injection. The rabbits were sacrificed 30 days after injections and the histopathological examination was performed. Results: No obvious change was detected in all four groups from the 1st day to the 3rd day after injection in terms of tearing, hyperaemia, and chemosis. There was no visible sign of inflammation or necrosis, and also no histological change in both clinical and histopathological examinations. Conclusion: Subconjunctival injection of doxycycline with different dosages of 250 to 2000 ug in 0.1cc in rabbit eyes was safe and no clinical or histological changes were observed after one month.