The natural history of meibomian glands: Age-related changes in an asymptomatic population

Abstract

Purpose: An understanding of the meibomian gland (MG) changes occurring naturally over time is important in order to identify pathology and dysfunctional changes. This study investigated measures of MG function and structure in a normal asymptomatic population aged between 25-65 years.

Methods: 156 asymptomatic subjects (91 females) with no pre-existing ocular and systemic abnormalities were recruited and divided into four age groups: 25-34, 35-44, 45-54, and 55-65 (n = 45, 38, 39, and 34, respectively). Asymptomatic subjects were defined as between “normal to mild” and “normal to marginal dry eye” as categorised by the Ocular Surface Disease Index and McMonnies Dry Eye questionnaires, respectively. At a single visit, the following MG measures were collected: meibum quality (MQ) and MG expressibility (MGE) of the lower lid, and infra-red meibography of the upper and lower lids which yielded the MG loss factor (MGLF) i.e. the ratio of the area of MG drop-out to the total area of MG measured. Other clinical measures included osmolarity, lid margin and lashes appearance, conjunctival redness and roughness, lipid layer appearance, tear meniscus height, non-invasive and invasive tear break-up-time (TBUT), corneal fluorescein staining and conjunctival and lid margin lissamine green staining. Data from the worst eyes of each subject were included for data analysis.

Results: There was a significant worsening in the grade severity of MQ (p=0.03), MGE (p<0.01) and MGLF (p=0.001) with increasing age. MGLF showed a steady reduction as age increased (p<0.04), while MQ and MGE both became worse only after 44 years of age (p<0.04). There was a linear increase in the flakes and scales on the lid lashes with age (p<0.01). Lipid layer thickness, tear meniscus height, non-invasive and invasive TBUTs increased beyond 54 years of age (p<0.04), with a corresponding decrease in osmolarity (p<0.001).

Conclusions: Progressive meibomian gland loss occurs normally with age, accompanied by reduced quality and quantity of the meibum produced. These changes can occur without corresponding increases in dry eye symptoms. In older individuals without dry eye symptoms, increased tear volume and reduced osmolarity may counterbalance the effects of meibomian gland changes.

Keywords: 486 cornea: tears/tear film/dry eye • 461 clinical (human) or epidemiologic studies: natural history • 526 eyelid