Purpose: To compare clinical tear film break-up time measurements obtained non-invasively, with those measured following minimal and conventional volumes of fluorescein instillation.
Methods: Forty-one subjects (20 male, 21 female, mean±SD age 34±11years), with or without dry eye, participated in a prospective cross-over study. Tear film break-up time was measured by the Tearscope Plus™ with fine grid insert. Measurements were made in triplicate, with no fluorescein instillation (NIBUT), then following application of a minimal volume of 1μl fluorescein from the Dry Eye Test™ (mTBUT), and finally with 15-30μl of fluid instilled via a conventional fluorescein strip (TBUT). A fifteen-minute interval between each set of measurements minimised the risk of residual contamination effects.
Results: All three techniques displayed statistically significant pairwise correlation (all p<0.001). TBUT values were significantly shorter than both NIBUT (geometric mean 8.6s versus 10.9s, p=0.03) and mTBUT (geometric mean 8.6s versus 10.6s, p=0.03), and demonstrated narrower spread (both p<0.05). No significant differences were detected between NIBUT and mTBUT (all p>0.05).
Conclusions: Tear film break-up time values measured with conventional fluorescein instillation were shortened, while minimal fluorescein instillation and non-invasive methods produced comparable readings. This suggests that minimising instilled volumes can reduce the impact of fluorescein on clinical measurements of tear film stability.
Keywords: Break-up time; Fluorescein; Tear film; Tear film stability.
Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.