The aging Meibomian gland : an in vivo confocal study

PURPOSE. To evaluate age-related Meibomian gland (MG) changes by in vivo laser scanning confocal microscopy (LSCM). METHODS. Asymptomatic healthy subjects (n = 100, age range 20-83 years) with an Ocular Surface Disease Index score of less than 13 were consecutively enrolled. Two additional groups, one composed of subjects under 40 years of age (n = 12) and one composed of subjects over 65 years (n = 12), were included without inclusion or exclusion criteria. All subjects underwent a full ocular surface evaluation, and one eye of each subject was examined by LSCM to quantify the lower lid MG acinar unit diameters and densities, orifice diameters, secretion reflectivity, interstices inhomogeneity, and acinar wall inhomogeneity. RESULTS. In the asymptomatic population, MG density and diameter decreased with age (P < 0.001 and P < 0.01, respectively), and secretion reflectivity and inhomogeneity of acinar walls increased (P < 0.001). For the under 40-year-old subjects and the over 65-year-old subjects included without any inclusion or exclusion criteria, acinar unit density decreased with age, and secretion reflectivity, and wall inhomogeneity increased (P < 0.01). There was no significant difference between the mean acinar diameters of these two groups. CONCLUSIONS. In vivo LSCM imaging of age-related MG changes showed the histologic features underlying the clinically observed MG dropout. Asymptomatic older subjects mainly showed signs of atrophic, nonobstructive, age-related MG dysfunction. Comparing volunteers with and without ocular surface symptoms, LSCM can provide important information regarding the boundary between physiologic and pathologic MG aging.