Dry eye patients have been divided primarily into two categories, evaporative or tear
production-deficient. 1 In both cases, increased tear evaporation and by extension,
evaporation rate, is a significant parameter in the etiology and pathogenesis of dry eye.
Paradoxically, the use of tear supplements has been shown to exacerbate tear evaporative
loss. 2 Theoretically, tear supplements should cause minimal increases in evaporation and
ideally, should reduce evaporation of the tear film.

Purpose: To investigate the effect of the instillation of an oil and water emulsion on the
evaporation rate from the human tear film. The effects of the emulsion were compared to two
other preparations: hypermellose and castor oil. Methods: Tear evaporation was measured
using a modified ServoMed evaporimeter mounted in a swim goggle attached to a slit-lamp.
Twelve young subjects (mean age 29 years, 6 male, 6 female) asymptomatic for dry eye as
assessed by a McMonnies dry-eye questionnaire, were recruited. Baseline evaporation …