Preclinical investigation of fluorometholone acetate as a potential new adjuvant during vitreous surgery

To examine the effects of intravitreal fluorometholone acetate (FMT) on the morphology and function of the retina and to investigate its possible use for vitreous surgery. Brown Norway rat eyes (n = 6, 12 groups) were injected with 0.05 ml of SF6 gas for vitrectomization. Four weeks later, FMT solution was injected into the vitreous cavity/subretinal space of the vitrectomized eyes at doses of 10, 20, and 40 mg/ml (0.05 ml/eye, n = 12 for each group). The retinal function was evaluated by electroretinography (ERG) at 4 and 8 weeks after FMT injection. Retinal toxicity was also assessed histologically by a light microscopy. Sham-operated eyes (0.05 ml of irrigating solution, n = 12) were used as control animals. FMT-assisted pars plana vitrectomy with internal limiting membrane (ILM) peeling was performed in primate eyes (n = 2). Retinal toxicity was assessed by ophthalmoscope, fluorescein angiography and electron microscopy three months after the vitreous surgery. There was no remarkable reduction in any ERG waves at either time interval at 4 and 8 weeks after the intravitreal/subretinal injection of FMT. No obvious histological change was observed in any of the rat eyes either. Using ophthalmoscope, fluorescein angiography and electron microscopy, the appearance of the primate retinas remained to be in a non-pathological condition. FMT appears to be a potentially useful tool in assisting vitreous surgery including safe ILM peeling.