Sulfur Mustard Toxicity of the Rabbit Eye: An Ultrastructural Study

Abstract

Whole body exposure to sulfur mustard (HD) produces cutaneous, respiratory, and ocular impairment. Of these, ocular damage causes the most immediate incapacitation. Heretofore, characterization of HD ocular toxicity has been limited largely to gross and histological observations. In this study we explore ultrastructural effects of ocular HD exposure and establish correlations with ultrastructural data already documented for dermal exposure. Anesthetized rabbits were exposed to 0.4 μl liquid HD placed directly on the cornea. At 24 h postexposure, animals were euthanized for routine necropsy evaluations. Eyes processed for ultrastructural analysis showed consistent focal necrotic sloughing of corneal epithelial cells at the site of exposure. In addition, a spreading detachment of epithelium occurred because of a disabling of basal cell hemidesmosomes, which cleaved the epithelium from the stroma at the level of the lamina lucida. This led to large expanses of denuded stroma, with remnants of anchoring filaments, fragments of basal cell membranes, and cellular debris attached to the remaining lamina densa. Edema, degenerating fibroblasts, and inflammatory cellular infiltrates were persistent stromal responses at the site of exposure. These ultrastructural effects of corneal exposure appear to be consistent with that reported previously for skin, perhaps providing shared anatomical considerations for the development of effective prophylaxis and therapy.