Relationship between tear-meniscus parameters and tear-film breakup.
OBJECTIVE
Several flaws exist with the lipid-diffusion model for tear-film 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 proposed to influence the formation of breaks in the tear film.


METHODS
Measurements of noninvasive breakup time (NIBUT) and tear-meniscus radius of curvature, height, width, and cross-sectional area (TMC, TMH, TMW, and XSA) were made for 15 aqueous-deficient dry-eye and 15 age-matched control subjects. An optic section of the inferior tear meniscus (colored with a minute volume of fluorescein) was photographed at x120 magnification, and images were computer analyzed.


RESULTS
A significant positive correlation was found between log NIBUT and TMC (r2 = 0.141; p < 0.05). Furthermore, all subjects with TMC < 0.340 mm had NIBUT < 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 rapid tear-film breakup times is consistent with the meniscus model of tear-film rupture. However, a causal relationship has yet to be established.
Golding
T R
TR
Centre for Eye Research, School of Optometry, Queensland University of Technology, Australia.
Bruce
A S
AS
Mainstone
J C
JC
D000287:Administration, Topical; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001767:Blinking / Q000502:physiology; D003287:Contrast Media; D015352:Dry Eye Syndromes / Q000503:physiopathology*; D005260:Female; D019793:Fluorescein; D006801:Humans; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions; D015203:Reproducibility of Results; D013500:Surface Tension; D013666:Tears / Q000502:physiology*; D014741:Video Recording
D003287:Contrast Media; D009883:Ophthalmic Solutions; D019793:Fluorescein