Purpose The current study evaluated the meibum and lid margin microbiome of eyelids with chalazion and compared it with contralateral uninvolved eyelids and healthy controls.

Methods Chalazion contents (group 1) and expressed meibum swabs from the lid margins of seven patients with chalazion (mean age 29±12 years; >6 weeks chalazia duration) and age-matched healthy controls were sequenced using next-generation 16S rDNA V3-V4 variable region sequencing. The meibum from the contralateral eye of patient with chalazion served as sample control (group 2), and healthy individuals served as negative control (group 3). The contents were also plated using conventional culture techniques.

Results Meibomian glands expressed thick turbid meibum in the area of chalazion in five out of seven eyelids. Contralateral uninvolved eyelids and healthy control glands were expressible with clear meibum. The mean Schirmer I value was 24.6±4.9 mm. Lid margin and meibum microbiome profiling revealed significant differences between the patients (involved or uninvolved sides) and healthy controls. The predominant phyla were Proteobacteria, Bacteroidota and Actinobacteria in all three groups. Acinetobacter, Moraxella and Paracoccus were the predominant genera in groups 1 and 2. Significant differences were noted in the predominant genera between group 3 versus groups 1 and 2. Principal coordinate analysis revealed overlap between groups 1 and 2, whereas group 3 had a distinct cluster. None of the culture media (for aerobic, anaerobic bacteria and fungus) showed any bacterial growth.

Conclusion In patients with unilateral chalazion, involved and uninvolved eyelids share similar lid margin and meibum microbiome but differ from the healthy controls.