Menisci and fullness of the blink in dry eye

Purpose. This study was to investigate the role of the upper meniscus in tear film formation and blinking. Methods. One microliter of 2% fluorescein was instilled under the upper lid of 15 dry eye (DE) and 15 control subjects. Subjects were instructed to blink partially and hold the eye open as long as possible, and analysis of tear breakup dynamics was used to quantify the area of breakup. This procedure was repeated following a full blink. Meniscus height was measured from digital videos. Results. Both menisci were significantly decreased in DE compared with controls (p < 0.02, t test). Tear breakup dynamics analysis showed that significantly greater areas of breakup occurred with full compared with incomplete blinks in DE (p < 0.003 Mann Whitney U test), but not in controls. Conclusions. A stable tear film can be deposited by the upper meniscus alone following a partial blink, without contribution from the lower meniscus. The increased tear stability of partial blinks in DE may be due to less stretching of the already fragile tear film compared with a full blink, which covers more surface area.