Natural history of dry eye disease: Perspectives from inter-ethnic comparison studies

Asian ethnicity is a mostly consistent dry eye disease (DED) risk factor. Co-located ethnic population studies, reducing potential confounding effects of methodological and environmental heterogeneity, may help explain DED natural history. From 96 references identified through the systematic literature search strategy of the current review, 3 relevant studies possessed sufficient methodological homogeneity for pooled analysis. Results show earliest disparities detected between Asian and Caucasian populations being higher degrees of incomplete blinking and lid wiper epitheliopathy in pediatric Asian participants, likely associated with anatomically predisposed increased eyelid tension. Interethnic divergence in meibomian gland dropout in the young adult population follows, while other ocular surface characteristics remain within physiological limits; significant differences in meibomian gland function, tear film stability and osmolarity, DED symptomology and overall disease diagnosis (based on TFOS DEWS II criteria) do not manifest until the middle adult population; and disparities in corneal and conjunctival staining become significant only with older age. Aqueous tear deficiency appears less likely than evaporative mechanisms to be implicated in the Asian ethnic propensity towards DED development. Two retrospective studies identified in the systematic literature search, further indicate susceptibility of the Asian population to iatrogenic DED secondary to contact lens wear and refractive surgery. Overall, the observation of increasing interethnic ocular surface differences throughout life has potential to offer valuable insight into the natural history of dry eye disease development.