Tear meniscus height (TMH) is an indirect measurement of tear film volume. This study investigated the temporal changes in the TMH during the blink interval in the morning (8–9 am) and at the end of the day (5–6 pm) in both soft contact lens (CL) and nonlens wearers (NLW).
Fifty participants (25 CL; 25 NLW) were evaluated for their subjective symptoms, TMH, noninvasive break up time, and bulbar hyperemia at the am and pm visits on the same day. The TMH was measured at set intervals between 2 and 15 sec during the blink interval, using an optical coherence tomographer.
The NLW group revealed no changes in a variety of symptoms during the day, whereas the CL group reported an increase in dryness (P=0.03) and grittiness (P=0.02) over the day. For both groups, the TMH and calculated tear meniscus volume revealed lower values immediately after the blink and increased progressively afterwards, mainly due to reflex tearing. The am tear meniscus volume values tended to be higher than the pm values for both groups, but this was not significant (NLW P=0.13; CL P=0.82). Noninvasive break up time deteriorated during the day for both groups but was only significant for the CL group (P=0.002), whereas bulbar hyperemia revealed no statistically significant change for either group.
Reflex tearing may play a substantial role in the TMH differences observed over the blink interval. Standardization of the time when a TMH measurement is performed will be valuable in comparing tear film clinical studies.
From the Ecole d'optometrie (E.B.), Universite de Montreal, Montreal, Quebec, Canada; and Centre for Contact Lens Research (L.J., T.S., C.W.), University of Waterloo, Waterloo, Ontario, Canada.
Supported by Canada Foundation for Innovation and Ontario Research and Development Challenge Fund for an infrastructure grant for the OCT; Université de Montréal, the Fondation des maladies de l'oeil du Québec, and ALCON Canada for sabbatical support for EB. Partially supported by CIBA Vision for an unrestricted Education Grant.
Address correspondence and reprint requests to Etty Bitton, O.D., M.Sc., Ecole d'optometrie, Universite de Montreal, Montreal, 3744 Jean Brillant, Suite 260-7, Montreal, Quebec, Canada, H3T 1P1; e-mail: firstname.lastname@example.org.
Accepted February 25, 2010.