Functional and Morphologic Changes of Meibomian Glands in an Asymptomatic Adult Population

The aim of the study was to understand natural changes of meibomian glands (MG) that occur with aging in the absence of any ocular pathology or ocular discomfort symptoms, to differentiate between "age normal" and pathologic or dysfunctional changes of the MG.

A total of 185 subjects (109 females) with no pre-existing ocular and systemic abnormalities were recruited and divided into four age groups: 25 to 34, 35 to 44, 45 to 54, and 55 to 66 years. At a single visit, the following MG measures were collected: meibum quality (MQ) and MG expressibility (MGE) of the lower lid, and MG drop-out score (meiboscale) using infrared meibography of the upper and lower lids. Assessments of anterior eye, tear function variables, noninvasive and invasive tear breakup time (TBUT), corneal integrity, and lid wiper epitheliopathy were also performed during the visit. An Ocular Surface Disease Index (OSDI) questionnaire was used to record dry eye symptoms. Meibum lipids samples were collected and analyzed.

A majority of the study population (61%) was asymptomatic. There was a significant worsening in the MQ (P< 0.048), MGE (P < 0.03), and meiboscale (P < 0.01) with increasing age. Significant increase was observed in anterior blepharitis (P < 0.001) and telangiectasia (P< 0.02) with aging. Interestingly, tear osmolarity decreased significantly (P < 0.001), while tear meniscus height (P < 0.001) and invasive TBUT (P = 0.02) increased with increase in age. There was no significant association between MG variables and sex, ocular discomfort symptoms, or meibum lipids classes.

Progressive MG loss occurs normally with age accompanied by reduced quality and quantity of the meibum produced. However, clinical presentation of ocular discomfort symptoms is stalled without corresponding disruption to tear function.