RELATIONSHIP BETWEEN TEAR-MENISCUS PARAMETERS AND TEAR-FILM BREAKUP

Purpose. Several flaws exist with the lipid-diffusion model for tear-f ilm breakup. The aim of this study was to test an alternative model of tear-film rupture in which the negative hydrostatic pressure in each tear meniscus (related to the tear-meniscus radius of curvature) is pr oposed to influence the formation of breaks in the tear film. Methods, Measurements of noninvasive breakup time (NIBUT) and tear-meniscus ra dius of curvature, height, width, and cross-sectional area (TMC, TMH, TMW, and XSA) were made for 15 aqueous-deficient dry-eye and 15 age-ma tched control subjects. An optic section of the inferior tear meniscus (colored with a minute volume of fluorescein) was photographed at x12 0 magnification, and images were computer analyzed. Results, A signifi cant positive correlation was found between log NIBUT and TMC (r(2) = 0.141; p < 0.05). Furthermore, all subjects with TMC <0.340 mm had NIB UT <15 s, and two thirds of subjects with TMC >0.340 mm had NIBUT >15 s, There was a moderate linear relationship between TMH and log NIBUT, indicating an association between tear volume and tear stability. TMC , TMH, and tear meniscus XSA measurements all showed good reliability. Conclusions, The association between highly curved tear menisci and r apid tear-film breakup times is consistent with the meniscus model of tear-film rupture. However, a causal relationship has yet to be establ ished.