Conjunctival epithelium thickened in one to two weeks postinjury, but the corneal epithelial layer remained very thin, often with "skip" areas referred to as defects. When such defects were long-lasting, necrotic ulcers, with or without bacterial infection, often supervened. Depending on the severity of the original injury, a scarring, or "hazing," of the corneal stroma was noted.
Lewisite injuries cause necrosis of the deep corneal layers with loss of nuclei of all keratocytes and loss of normal staining characteristics in collagen fibers (Adler et al., 1947). Neutrophils invade the stroma at 24 hours but are replaced by round, chronic inflammatory cells at the end of 10 days. Corneal vascularization is not visible until 5 days after the injury, becoming intense at 14 days. Topical British Anti-Lewisite treatment diminished the severity of these injuries only if given within two to five minutes of injury (Hughes, 1946).
Long-term studies of the effect of sulfur mustard were conducted by Mann and Pullinger (1944). Over a period of 18 months they intermittently examined 138 rabbits injured by sulfur mustard (Figure 8-2). Based on the lifetime of a rabbit as one-tenth that of man, an observation period of 18 months would be sufficient time to develop delayed keratitis in this experimental animal. The results showed that, similar to the human condition, migration of fatty or cholesterin deposits to the surface of the eye could occur after 7 to 8 months and cause recurrent secondary ulceration. In these models of severe burns, it can be concluded that delayed and recurrent keratitis is demonstrable and reproducible.
Comparison of sulfur mustard injuries to those sustained with Lewisite is summarized in Table 8-3. A summary of the toxicology of Lewisite liquid and vapor is separately tabulated in Table 8-2. Many of the rabbits in the Lewisite study were watched for more than one year; no secondary lipoid degeneration or cholesterin deposition was noted, nor any long-term effect, in particular (Mann et al., 1946).
A large number of injuries occurred in the production of sulfur mustard. A summary of the toxic accidents in all three mustard gas production factories in England showed that 10.4 percent of 939 eye