Clinical assessment of the lower tear meniscus height

Abstract

Purpose: Different values of the lower tear meniscus height (TMH) can be obtained depending on the method and technique of measurement employed. This study aimed to assess (1) differences between the absolute (TMH-A), reflex (TMH-R) and fluorescein (TMH-F) lower tear meniscus heights, (2) differences between the central (TMH-R), nasal (TMH-RN) and temporal (TMH-RT) reflex lower tear meniscus heights and (3) the amount of fluorescein present in the lower tear meniscus, 5 min after fluorescein instillation (TMH-FV). Methods: Thirty four young healthy subjects were included in the study. The lower tear meniscus height (TMH) was measured using an eye piece graticule inserted into a slit-lamp. Results: Mean ± S.D. values of TMH-A, TMH-R, TMH-RN, TMH-RT, TMH-F and TMH-FV of 0.25 ± 0.08, 0.13 ± 0.05, 0.23 ± 0.06, 0.21 ± 0.05, 0.27 ± 0.11 and 0.004 ± 0.001 mm, respectively were found. The TMH-R was significantly lower than the TMH-A and the TMH-F (p < 0.0001). The TMH-RN and TMH-RT were significantly higher than the TMH-R (p < 0.0001). The TMH-F was significant higher than the TMH-FV (p < 0.0001). No significant differences were found between the TMH-A and TMH-F (p = 0.2), and between the TMH-RN and TMH-RT (p = 0.36). Conclusion: Careful instillation of fluorescein does not affect normal TMH values. Fluorescein is washed out from the lower tear meniscus 5 min after instillation. Higher values of the TMH can be found at nasal and temporal locations compared to the center of the lower eye lid.