초자체 절제술 관류액에 혼합된 Cefazolin 항생제의 안전농도에 관한 실험적 관찰

초록

Management of infectious endophthalmitis presents one of the most challenging problems in ophthalmology. Retention of vision even in culture-proven cases has remained consistently poor. Recently vitrectomy is introduced into the management of endophthalmitis, often with antibiotics in the infusion 리uid, to promote intraocular drug diffusion. In this animal experiment, the author studied ultrastructural changes of the rabbit retina caused by the various concentrations of cefazolin mixed in the infusion fluid to help determine the non-toxic concentration. Pars plana core vitrectomy was performed with infustion fluid containing 40, 10, 5, and 1 ㎍/ml cefazolin on the 4 eyes of 4 rabbits respectively. Eyeballs were enucleated 2 weeks after vitrectomy and specimens were immediately processed for transmission electron microscopic examination. Same procedures were repeated using gentamicin to compare with the already known toxicity. Osmolar concentration of the each infusion fluid was checked to evaluate the possible high osmolar toxicity. The results were as follows: 1. In the 40 ㎍/ml group, pyknosis and cytoplasmic degeneration were observed in the inner and outer nuclear layer, and photoreceptor inner segment showed swelling and destruction of organelles, resulting in prominent fiber baskets of Mu¨ller cell processes. Retinal pigment epithelium also showed loss of apical microvilli, breaks in the cytoplasm, and widening of basal infolding. 2. Findings in the 10 and 5㎍/㎖ groups were similar to the 40 ㎍/㎖ group. 3. In the 1㎍/㎖ group, the changes were reduced but not as normal as in the comparison group. 4. It was confirmed that the changes noticed in the 40, 10, 5, and 1㎍/㎖ groups were not related with high osmolar concentration of the infusion fluid. In comparison with the gentamicin experiment, we may conclude, in spite of the ultrastructural changes noticed in the 1㎍/㎖ group, that these changes are reversible and functionally unharmful, provided that those additional tests such as electroretinography and fluorescein angiography be supplemented. Taking into consideration the mechanism by which cephalosporin makes retinal toxicity, we could suppose that this antibiotics might reach the enzyme-rich retinal cells and inhibit the enzyme-linked metabolism to make the morphological and functional changes in them.

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