High dose intramuscular methylprednisolone in experimental Staphylococcus aureus endophthalmitis

We attempted to determine whether treatment using intramuscular methylpredn isolone plus intravitreal vancomycin decreased ocular inflammation and pres erved retinal function better in experimental Staphylococcus aureus (S. aur eus) endophthalmitis than treatment with intravitreal vancomycin alone. Six teen rabbits received intravitreal inoculations in both eyes with S, aureus and the rabbits were divided into two groups (group I and group II) of eig ht rabbits each. Group I rabbits were treated with one injection of intravi treal vancomycin in each eye at either 24, 36, 48 or 72 hours after bacteri al inoculation followed by seven consecutive days of high dose intramuscula r methylprednisolone (30 mg/kg per day). Group II rabbits were treated with only one intravitreal injection of vancomycin in each eye at equivalent ti me intervals as in Group I. Clinical evaluations of ocular inflammation wer e performed by slit-lamp biomicroscopy and indirect ophthalmoscopy. Electro retinography (ERG) was performed eight days after bacterial inoculation to assess retinal function in all eyes. The combination of intramuscular methy lprednisolone and intravitreal vancomycin resulted in a degree of ocular in flammation equal to eyes treated with intravitreal vancomycin alone at all treatment intervals. ERG responses were not significantly different in eith er group. A single intravitreal injection of vancomycin plus daily intramus cular methylprednisolone for seven days were found neither to decrease ocul ar inflammation nor preserve retinal function better than a single intravit real injection of vancomycin in our experimental model of S. aureus endopht halmitis.