Quantitative evaluation of tear meniscus height from fluorescein photographs

Purpose: To describe a method of quantifying the tear meniscus height (TMH) and using these values to diagnose patients with dry eye. Methods: Thirty-eight eyes of 19 healthy subjects and 14 patients diagnosed with dry eye were studied. Each eye received 2 mu L of 1% fluorescein-sodium solution in the conjunctival sac, and digital photographs were taken of the external surface of the eye with a fundus camera. The tear meniscus was extracted from the digitalized image and used to measure the TMH with NIH image software. The correlation between the mean TMH and Schirmer test values or cotton-thread test values was evaluated. Results: The means of the upper and lower TMH in healthy subjects were 0.22 +/- 0.06 and 0.24 +/- 0.08 mm, respectively. The comparable values in patients with dry eye were 0.17 +/- 0.04 and 0.17 +/- 0.07 mm (upper TMS, P = 0.01; lower TMH, P = 0.04; unpaired t test). A significant correlation was found between the TMH and Schirmer test values (r = 0.72, P = 0.01) but not with cotton-thread test values. Conclusions: Fluorescein photographs of the eye can be used to quantify the upper and lower TMH separately and simultaneously without specialized equipment. This technique can be used for the diagnosis of dry eye.