Meibomian Gland Morphology: The Influence of Structural Variations on Gland Function and Ocular Surface Parameters.

ABSTRACT

PURPOSE: To objectively and quantitatively characterize meibomian gland morphology and to investigate the influence of morphological variations on gland function and ocular surface and tear film parameters. METHODS: One hundred fifty subjects were enrolled. The examinations included tear osmolarity, tear meniscus height, bulbar conjunctival hyperemia, noninvasive tear film breakup time, lid margin thickness, foam secretion, meibomian gland expressibility, count of functioning glands, corneal and conjunctival staining, fluorescein breakup time, lid wiper epitheliopathy, and Schirmer test. Patient symptoms were assessed using the Ocular Surface Disease Index questionnaire. Images from noncontact meibography were analyzed using an automated method that objectively estimates dropout area, number of glands, gland length and width, and gland irregularity. RESULTS: Gland irregularity highly correlated with dropout area (r = -0.4, P < 0.001) and showed significant partial correlations with fluorescein breakup time (r = 0.162, P = 0.049) and the Ocular Surface Disease Index questionnaire (r = -0.250, P = 0.002) Subjects with dropout area <32% were divided into 2 groups high and low irregularity. Gland expressibility was statistically significantly different between the 2 groups (U = 319.5, P = 0.006). In the high irregularity group, gland irregularity correlated with the Schirmer test (r = 0.530, P = 0.001) and corneal fluorescein staining (r = -0.377, P = 0.021). CONCLUSIONS: Automated morphological analysis of meibomian gland structure provides additional quantitative and objective information regarding gland morphology. The link between dropout area and gland function is not clear. Assessment of gland irregularity might better predict gland function and its effects on ocular surface and tear film parameters.