Conjunctival surface damage distribution in keratoconjunctivitis sicca. An impression cytology study.

Impression cytology was used to study the ocular surface of 32 eyes with keratoconjunctivitis sicca. Among these eyes, on the basis of the results of the Schirmer I test, two groups of eyes have been identified. The first group with Schirmer test less than 5.5 mm/5 min showed decreased concentration of goblet cells and increased cytoplasm/nucleus ratio on all the areas of the bulbar conjunctiva. The second group, with Schirmer test greater than 5.5 mm/5 min, showed similar changes to be localized in the interpalpebral bulbar conjunctiva only, while the eye surface protected by the lids was almost normal. These observations suggest a pathogenetic role of tear evaporation in eyes with tear film instability even in the presence of a 'theoretically' normal tear production.