Bacterial endophthalmitis caused by intraocular surgery or penetrating wounds has long been a severe ophthalmologic problem. For several decades, antibiotics have been directly injected into the vitreous body as the treatment of endophthalmitis. Since then in order to come up with a treatment that would not cause toxic effect on the retina, experimental reports on many different effect of antibiotics on morphological changes and its safe doses have been documented today.
Tobramycin, which is two to four times more effective than gentamicin against Pseudomonas strains but less toxic, has been studied and experimented on rabbits or human retina by many investigators with ophthalmoscope, electroretinogram or light microscope. But these reports were not adequate for fine histological findings since the tissue were embedded in paraffin, and fine structural changes is not known well.
Author, by using 84 colored mature rabbits as experimental animals that tobramycin were injected into their vitreous bodies, observed gross findings seen throughout the days 1, 2, 4, 7, 14, 28 and 60. Also in order to observe the fine structures of retina, semithin and thin sections were performed after Epson embedding, then studied with both light and electron microscopic observation.
The following results were obtained:
1. A distinguishable structural changes were not observed in groups injected with 50mg of tobramycin.
2. Tissue changes: As time passed, through out the whole layer of retina, vacuolar degeneration in cytoplasm of nerve fiber layer, inner plexiform layer, ganglion cell and inner neuclear layer cells were seen. Also vacuolar changes within outer plexiform layer, karyolysis of outer neuclear layer, appearance of phagocytes occurred, clumping of pigment granules of pigment epithelium,
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