Every community has a few rough neighborhoods, and the ocular surface is no different. Researchers recently discovered a unique microbiome in freshly collected human limbal and forniceal tissue that differs from the structure and composition of the ocular surface microbiome as a whole. And it’s populated by a known troublemaker.

The team obtained conjunctival tissue from 23 patients undergoing pterygium surgery and compared the samples with data from a recent study of conjunctival surface swabs. The researchers analyzed microbial communities by extracting DNA, sequencing the 16S rRNA gene and performing molecular imaging.

They found a significant difference in bacterial community structure between the conjunctival surface and limbal and forniceal tissue, but no difference between the limbus and fornix. The team notes that limbal and forniceal samples were dominated by Pseudomonas (79.9%), which was found in low relative abundances on the conjunctival surface (6.3%).