Tear meniscus measurement in the diagnosis of dry eye

Abstract

PURPOSE: Assessment of the tear film meniscus is a quantitative, minimally invasive, direct measurement of tear film quantity. The aim of this study was to assess the efficacy of tear meniscus parameter measurement in the diagnosis of dry eye. METHODS: Tear meniscus radius of curvature, height, width and cross-sectional area (TMC, TMH, TMW, XSA) were determined by photographing an optic section of the inferior tear meniscus (colored with a min volume of fluorescein) at 12 x magnification, and then scanning developed images into a computer analysis program. Fifteen dry eye subjects and 15 age-matched controls were assessed. Dry eye subjects satisfied the criteria of a rose bengal staining score >/= 1, and a mean phenol red thread 15s wetted length </= 10 mm. RESULTS: TMC, TMH and XSA were all reduced in magnitude in the dry eye group compared to the control group (mean +/- SD; TMC: 0.314 +/- 0.160 mm vs. 0.545 +/- 0.259 mm, TMH: 0.244 +/- 0.089 mm vs. 0.461 +/- 00.173 mm, XSA: 0.0082 +/- 0.0048 mm2 vs. 0.0176 +/- 0.0103 mm2, ANOVA, p < 0.05). Both TMC and TMH showed good diagnostic accuracy (166.7% and 160% respectively), with a dry eye referent value of </=0.35 mm for each parameter. TMC and TMH also showed strong correlations with the cotton thread test, non-invasive breakup time, and ocular surface staining scores (p < 0.01). TMH was the most powerful predictor of tear film insufficiency. CONCLUSIONS: This study has shown tear meniscus assessment to be a useful alternative to existing tests for dry eye.