A comprehensive analysis of the microbiome of the eyelid’s skin, the conjunctival sac and meibomian gland (MG) meibum has revealed that meibomian glands are not sterile and that the meibum microbiome differs from that of the eyelid skin, even though the MG orifices were on the skin. Researchers detailed their results in Vancouver at ARVO 2019 earlier this year.

The Japanese study involved two groups of 12 subjects without any eye or skin disorders, one group between the ages of 20 and 35 and the other between 60 and 70. From one eye in each subject, researchers collected swab specimens from the lower eyelid skin, the lower conjunctival sac and the lower MG secretion. DNA sequencing helped determine the microbiomes for each area.

The mean relative abundance of Propionibacterium acnes in the meibum was 20.3% in the younger group and 10.7% in the older age group. The diversity of the microbiome decreased with age for both the meibum and the conjunctival sac. The mean diversity index of the microbiome in the meibum was 2.77 in the younger group and 1.78 the older group.

Researchers found that sex difference in the microbiome was not significant in either group. They concluded that age-related changes in the microbiome of meibum may affect the lipid metabolism of the MGs and homeostasis of the ocular surface.