We evaluated the retinal toxicity of antimicrobials (sulbenicillin, cefazolin, flomoxef, gentamicin, sisomicin, netilmicin, tobramycin, amikacin, vancomycin, ofloxacin, lomefloxacin, and miconazole) by the electroretinogram, before and after a single-shot intravitreal injection in rabbits. The clinical dosage for single-shot intravitreal injections which we recommend are 2 mg for sulbenicillin, 0.25 mg for cefazolin, 0.2 to 0.4 mg for flomoxef, 0.1 mg for gentamicin, 0.1 to 0.2 mg for netilmicin, 0.2 to 0.4 mg for amikacin, 0.2 mg for tobramycin, 1 mg for vancomycin, 0.2 mg for ofloxacin, 0.2 mg for lomefloxacin, and 0.05 mg for miconazole.