To evaluate the presence of free radicals in various drugs used in ophthalmology. Twenty five samples of drugs that are used by intracameral or intravitreal route, eleven samples of drugs used as fortified eye drop, thirty samples of topical commercial preparations that are used as long term, and eight samples of autologous serum were analyzed for total free radical presence using a kit for total oxidant status. The highest free radical concentration was in Moxifloxacin (Vigamox) in intracameral group, clindamycin in intravitreal group, brinzolamide in antiglaucoma group. Free radicals are present in drugs used in ophthalmology. The surgeon should consider the risk of oxidative damage in the presence of diseased eye.