Preservative-related problems in soft contact lens wearers.

Details of 61 patients are presented who, having worn soft contact lenses for many months, developed red eyes, conjunctival irritation with minimal discharge, and progressive loss of tolerance of the lenses. Investigations revealed an absence of infective agents and the clinical course after treatment with preservative-free solutions strongly suggested that preservatives, especially organic mercurials, were responsible for the changes. The corneal signs were slow to clear but after resolution the majority of patients were able to return to soft contact lens wear using a heat disinfection system with preservative-free solutions. Skin testing to a wide range of substances, including preservatives, contact lens solutions, and common sensitizers, revealed only one responder to Thiomersal out of 21 tested. However a rapid response followed conjunctival challenge with 0.005 per cent Thiomersal in normal saline in all subjects tested.