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Protection of the Corneal Epithelium with a Contact Lens

Mechanical protection of the corneal epithelium has been shown to reduce the irritation and improve the vision in a large series of cases of recurrent keratitis. The large and cumbersome scleral lenses were difficult to make, could only be worn for short periods by most individuals, and gave only a limited but welcome response. The development of soft contact lenses has dramatically improved our ability to protect the corneal epithelium in those patients when it is fragile (Pfister, 1986). Research to study the effect of soft contact lenses on the chronic relapsing keratitis after sulfur mustard injuries might provide an updated approach to mechanical protective devices.

Sulfur Mustard Compared to Alkali Injury: The Stromal Component

Sulfur mustard injuries bear distinct similarities to alkali or very strong acid injuries of the eye. If these two injuries present similar problems, then treatments that have been initiated for alkali burns of the eye might well be effective in mustard gas or Lewisite injuries. An animal model of the alkali-injured eye has yielded significant data showing that sodium  citrate and sodium  ascorbate, when applied topically to the eye, significantly reduce the incidence of corneal ulceration and perforation (Pfister and Paterson, 1980; Pfister et al., 1981, 1982). A national clinical trial on the treatment of human alkali-injured eyes with ascorbate and citrate is currently in progress. Other chelators that inactivate metalloproteases, such as collagenases, are also available. These metalloprotease inhibitors interfere with the enzymes leading to corneal ulceration. Although there is no clear-cut evidence available, it seems likely that this treatment could be quite effective in sulfur mustard injuries of the eye.

CONCLUSIONS

Acute, severe injury of the eye with sulfur mustard might result in recurrent corneal ulcerative disease for the remainder of the patient's life, with a maximum incidence occurring 15 to 20 years after the injury. Based on extensive data, there is a causal relationship between severe exposure to sulfur mustard and the development of delayed recurrent keratitis.

There is a causal relationship between exposure to sulfur mustard and the development of prolonged, intractable conjunctivitis.

There is evidence, in laboratory animals, to indicate that no causal relation is present between exposure to Lewisite and any long-term ocular disease process. However, any corneal scarring or vasculariza-



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