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Evaluation of lower tear meniscus shape with OCT
Author(s) -
BANDLITZ S,
PURSLOW C,
MURPHY PJ,
PULT H
Publication year - 2012
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2012.4641.x
Subject(s) - meniscus , radius of curvature , radius , mathematics , vertex (graph theory) , curvature , optical coherence tomography , optics , ophthalmology , geometry , physics , medicine , mean curvature , graph , combinatorics , mean curvature flow , computer science , computer security , incidence (geometry)
Purpose When measuring the tear meniscus radius and calculating tear volume, the anterior radius of the meniscus is assumed to be spherical. This study aimed to define the shape of the meniscus more precisely using high‐resolution optical coherence tomography (OCT). Methods Images of the lower tear meniscus of 30 normal subjects (8M, 22F; mean age 27.5±9.6yrs), recruited from the patient pool of Höhere Fachschule für Augenoptik, Cologne, Germany, were taken using the Zeiss Cirrus HD OCT. Applying ImageJ software, the tear meniscus height (TMH) was measured and the xy‐coordinates of 12 marked points on the anterior tear meniscus curve were determined. With these coordinates a graph was plotted and the best fitting trend‐line (defining TM curvature) was calculated. Furthermore, the distance between the edge of the lower eyelid and the vertex of the curve (TMH‐V) was calculated and compared to the half TMH (TMH‐H). Results Mean TMH was 0.24 SD±0.06mm. The mean fitting trend‐line appeared to be a quadratic equation (R‐squared range from 0.908 to 0.996). TMH‐V (0.12±0.04mm) and TMH‐H (0.12±0.03mm) were significantly correlated (r=0.62; p<0.001). The 95% LoA showed that the TMH‐V could be expected to be up to ‐0.07 mm below and 0.07 mm above the TMH‐H. Conclusion With high‐resolution OCT the anterior surface of tear meniscus was found to have a parabolic shape, which will help to calculate tear volume more precisely. To know the position of the parabolas vertices is useful when explaining the position of light reflexes from the tear meniscus particularly in reflective meniscometry.