Contact lenses in dry eyes.

This paper considers the dubious role of asymptomatic marginal reduction of tear production in the aetiology of contact lens intolerance and how in the light of our present knowledge and the tests available it is difficult to identify such marginal underproduction of tears. Contact lenses have a possible therapeutic role in the management of established dry eyes with and without conjunctival scarring and destructive corneal changes. All soft contact lenses have been shown to lose a considerable percentage of their fully hydrated water content when put in any eye and the presence of a contact lens in an eye has been shown to increase tear evaporation, irrespective of evaporation from the contact lens. Soft contact lenses would appear to be able to withstand considerable dehydration and yet maintain their optical quality and in the eye with inadequate tears a lens of lower water content will remain hydrated to a reasonable extent for a longer period than one of a higher water content. Contact lenses may be necessary in the dry eye to provide an optical surface to the cornea when it is the site of destructive changes. In the case of the severely dry eye it may be necessary to use a silicone soft lens with no water content in order to obviate the problems of dehydration. There are considerable dangers in such eyes with and without conjunctival and corneal destructive changes and a decision to fit a lens should not be taken lightly and without adequate provision for close follow up.