Immunological complications of soft contact lenses.

Immunologic reactions may be the basis of some complications associated with the use of soft contact lenses. In the case of giant papillary conjunctivitis, the antigen causing the problem is not known but is presumed to be protein adherent to the lenses. Superior limbic keratoconjunctivitis and dendritic corneal lesions related to soft contact lenses are associated with thimerosal, but occlusive patch tests do not demonstrate consistent delayed hypersensitivity responses to this preservative in these patients, suggesting that a toxic response may be involved. The association of corneal infiltrates and conjunctival hyperemia with delayed hypersensitivity to thimerosal probably represents the strongest immunologic association to date. These patients consistently show delayed hypersensitivity reactions to thimerosal in occlusive patch tests and intradermal tests.