Intravitreal antibiotic therapy with vancomycin and aminoglycoside. An experimental study of combination and repetitive injections
B. S. Oum, D. J. D'Amico and K. W. Wong
Retina Service, Massachusetts Eye and Ear Infirmary, Boston 02114.
We evaluated the retinal toxic reaction of combined intravitreal therapy
with regimens of 1.0 mg of vancomycin hydrochloride and 400 micrograms of
amikacin sulfate or 1.0 mg of vancomycin hydrochloride and 100 micrograms
of gentamicin sulfate in the rabbit eye. The effects of reinjecting each
combination a second or third time, separated by 48-hour intervals, were
also examined by ophthalmoscopy and light and transmission electron
microscopy. The initial administration of either regimen did not produce
toxic reaction. After two injections, five of six eyes with
vancomycin-gentamicin therapy and three of six eyes with
vancomycin-amikacin therapy displayed focal areas of retinal toxic reaction
on histologic study. After three injections, all eyes treated with either
regimen showed histologic evidence of more advanced retinal toxic reaction
primarily involving the outer retina and retinal pigment epithelium. The
present study demonstrates the safety of an initial intravitreal injection
of vancomycin and aminoglycoside but shows increasing retinal toxic
reaction with repetitive combination therapy.
