Prevalence of asymptomatic meibomian gland dysfunction in the general adult population: a systematic review and meta-analysis

Background/objectives Meibomian gland dysfunction (MGD) constitutes a highly prevalent ocular surface condition and is a major etiological factor in tear film instability and evaporative dry eye disease. Although MGD can be objectively identified based on structural and functional abnormalities of the meibomian glands, epidemiological studies rarely differentiate between symptomatic and asymptomatic disease. Asymptomatic meibomian gland dysfunction, characterized by structural or functional gland alterations in the absence of self-reported ocular symptoms, may constitute an early and frequently overlooked phase within the disease spectrum. The objective of this systematic review and meta-analysis was to quantify the prevalence of asymptomatic MGD among adult populations. Methods A comprehensive literature search was performed across PubMed, Web of Science, Scopus, ScienceDirect, and Google Scholar in accordance with the PRISMA guidelines. The review protocol was registered in PROSPERO (CRD420261283795). Cross-sectional and observational studies reporting the prevalence of asymptomatic MGD in adult populations were included. Data extraction and study selection were performed independently by two reviewers. A random-effects meta-analysis of proportions with logit transformation was applied using R software. Interstudy heterogeneity was quantified using the I 2 statistic, and possible contributors to variability were investigated through sensitivity analyses and meta-regression. Methodological quality and risk of bias were assessed using a modified version of the Newcastle-Ottawa Scale, while the overall certainty of the evidence was evaluated according to the GRADE approach. Results Eight cross-sectional studies published between 2012 and 2023 were included, comprising a total of 3,637 participants and 1,313 cases of asymptomatic MGD. The combined prevalence of asymptomatic MGD was 72.86% (95% CI: 19.33–96.78%), with substantial heterogeneity across studies ( I 2 = 98.8%). Sensitivity analyses identified one influential study; however, the overall finding of a high prevalence remained consistent. Meta-regression showed that sex distribution significantly contributed to between-study heterogeneity, while no association with year of publication was observed. The level of certainty for the pooled prevalence estimate was classified as low. Conclusion Asymptomatic MGD is highly prevalent among adult populations worldwide. These findings indicate that reliance on symptom-based assessment alone may underestimate the burden of early MGD. Early identification of asymptomatic gland abnormalities may support preventive approaches to reduce progression to symptomatic dry eye disease, although further standardized and prospective studies are required. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420261283795 , CRD420261283795.