Qualitative assessment of tear dynamics with fluorescein profilometry

Purpose: To describe a new methodology for tear-film dynamics assessment by observing fluorescein decay rate over time and to understand the relationship between the newly defined tear fluorescein washout rate (TFWR)and other measures of the tear film behaviour. Methods: Forty subjects (24F/16M) aged (mean +/- standard deviation) 31.8 +/- 14.2 years volunteered for the study. It consisted of the review of medical history, McMonnies questionnaire (McMQ), slit lamp examination, and TFWR using a newly-developed fluorescein profilometry. The repeatability of TFWR measurements was assessed. TFWR estimates were contrasted against patient age, McMQ score, daytime, fluorescein tear film breakup time (FTBUT), tear meniscus height (TMH) and blink frequency. Results: Mean repeatability of the method was 28.13 +/- 9.59%. The group mean TFWR was 39 +/- 23% at 30-s mark after the beginning of measurements, ranging from 1.4% to 83%. This indicates that TFWR is highly subject-dependent. Statistically significant correlations were found between the percentage TFWR and McMQ score (r2 =0.214, p = 0.001) as well as FTBUT (r2 =0.136, p = 0.009). No statistically significant correlations were found between TFWR and age, daytime, TMH, and blink frequency. Conclusions: Fluorescein profilometry allows clinicians to follow dynamic changes in the tear film on the entire ocular surface and may be used for qualitative assessment of the tear film dynamics.