OBJECTIVE: To determine the safety of intracamerally injected preservative-free 0.5% moxifloxacin/0.1% dexamethasone fixed-dose combination on the corneal endothelium in a rabbit model and compare it to intracamerally injected preservative-free 0.5% moxifloxacin.

METHODS: This experimental study included twenty eyes from ten albino rabbits. The eyes were assessed for baseline corneal clarity and anterior chamber (AC) inflammation using slit-lamp biomicroscopy. A specular microscope measured the corneal endothelial cell density (ECC) and corneal thickness (CT). Intracameral injections of 0.1 mL 0.5% moxifloxacin ophthalmic solution were administered to the 10 right eyes (IPFM group) and 0.1 mL of 0.5% moxifloxacin/0.1% dexamethasone fixed-dose preparation were administered to the 10 left eyes (IPFMDex group). In both groups, ECC, CT, corneal clarity, and AC inflammation at Day 1 (one day post-injection) and Day 7 (seven days post-injection) were compared with Day 0 (baseline). The IPFMDex group was also compared with the IPFM group at Days 0, 1, and 7. The endothelial cells of harvested corneas from both groups at Day 1 and 7 were stained with trypan blue and alizarin red, and compared for endothelial cell damage (ECD). Data were analyzed using paired and independent sample t-tests.

RESULTS: In both the IPFM and IPFMDex groups, ECC and CT at Day 1 (IPFM: ECC p=0.07, CT p=0.76; IPFMDex: ECC p=0.41, CT p=0.94) and Day 7 (IPFM: ECC p=0.95, CT p=0.28; IPFMDex: ECC p=0.29, CT p=0.34) were not different from Day 0 (baseline). No significant difference in ECC, CT, and ECD were found between the IPFM and IPFMDex groups at Day 1 (ECC p=0.82, CT p=0.36, ECD p=0.96) and Day 7 (ECC p=0.95, CT p=0.22, ECD p=0.61). Throughout the study, the cornea in both groups were clear and showed no signs of AC inflammation.

CONCLUSION: Intracameral injection of preservative-free moxifloxacin/dexamethasone fixed-dose formulation was safe on the rabbit corneal endothelium and was no different from preservative-free moxifloxacin.