Blepharitis driven by microbiome dysbiosis and Demodex infestation: possible pathogenic mechanisms

Blepharitis is a chronic inflammation of the eyelid margin that is mediated by the immune system. It is one of the common ocular surface diseases and often leads to serious sequelae that threaten vision, such as dry eye syndrome due to insufficient tear secretion, corneal neovascularization, and stubborn chalazion. Elucidating its precise etiology is therefore imperative. Emerging high-throughput sequencing and metagenomic analyses have unveiled a quantitative and qualitative disruption of the periocular microbiome (dysbiosis), characterized by the expansion of specific bacterial species such as Staphylococcus aureus, coupled with episodic blooms of Demodex. These perturbations are no longer considered epiphenomena. In this review, we reveal the possible mechanisms of the role of blepharitis and microbiota dysbiosis.