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Dynamic changes in tear meniscus curvature at the rigid contact lens edge
Norihiko Yokoi1, Kunio Maruyama, Shigeru Kinoshita
1Department of Ophthalmology, Kyoto Prefectural University of Medicine, Japan. nyokoi@ophth.kpu-m.ac.jp
Purpose:
To investigate dynamic changes in tear meniscus curvature at the edge of a rigid contact lens.
Methods:
Four eyes of four men and seven eyes of seven women who were daily wearers of rigid contact lenses were enrolled in the study. A digital video-meniscometer was used to observe real-time changes in tear meniscus curvature. Quantitative measurements have not previously been made at these locations.
Results:
The meniscus at the lens edge showed stereotypical changes with each blink. The meniscus radius is lowest at the end of the up-phase of the blink and then increases to a steady value 0.213 +/- 0.024 mm (mean +/- SD, n = 6) after about 1 second.
Conclusions:
The video-meniscometer permitted observation of real-time changes in meniscus curvature at the contact lens edge during the blink. The short radius at the end of the up-phase suggests that tears are drawn away from the lens during the upward movement of the lid and lens. The restoration of a longer radius of curvature in the period that follows is thought to be due to a flow of fluid into the meniscus from the neighboring tear film.