Fluorophotometric measurement of human tear turnover rate.

Measurement of tear turnover rate using an automated scanning fluorophotometer (FluorotronR) was compared to Schirmer test results without anesthesia in young adults with no known ocular disorder. After the instillation of fluorescein, tear film fluorescence, expressed as fluorescein concentration equivalent, decreased exponentially in a linear fashion with time. The mean tear turnover rate was 30% per minute. Contact lens wearers had higher mean tear turnover rates when compared with non-contact lens wearers, but differences were not statistically significant. Half of tested eyes demonstrated total wetting of Schirmer Tear Test StripsR. Higher mean tear turnover rates were associated with complete wetting of the Schirmer test strips. There was no significant correlation between Schirmer paper wetting of less than 30 mm and fluorescein turnover rate.