Topical Glaucoma Therapy Is Associated With Alterations of the Ocular Surface MicrobiomeOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study investigated the ocular surface microbiome in patients with unilateral or asymmetric glaucoma who were using topical ophthalmic medications in only one eye. Researchers used V3-V4 16S rRNA sequencing on ocular surface swabs to characterize microbial diversity and composition. They then tested whether differences in microbial composition were related to measures of ocular surface disease, including tear meniscus height, tear break-up time, and Dry Eye Questionnaire scores.
Who was studied?
The study included 17 subjects total. Ten were patients with asymmetric or unilateral glaucoma who used topical glaucoma therapy in only one eye, allowing comparison between their treated and untreated eyes. Seven were age-matched healthy controls with no history of ocular disease or eyedrop use, and samples were grouped into three categories: treated glaucomatous eyes, untreated contralateral eyes, and healthy control eyes.
What were the most important findings?
Both the treated and the untreated eyes of glaucoma patients showed significantly greater alpha-diversity and a greater relative abundance of gram-negative organisms compared to healthy control eyes. This pattern occurred even in the contralateral eye that received no eyedrops, suggesting a systemic or bilateral effect rather than one confined to the treated eye alone. The microbial composition of patient eyes was also associated with decreased tear meniscus height and decreased tear break-up time, linking microbiome alterations to signs of ocular surface disease.
What are the greatest implications of this study?
The findings suggest that topical glaucoma therapy is associated with ocular surface microbiome shifts that extend beyond the directly treated eye, potentially through systemic exposure or shared tear film dynamics. Because these microbial changes correlated with impaired tear film stability, the results implicate the ocular surface microbiome as a factor in medication-related ocular surface disease among glaucoma patients. This raises the possibility that microbiome monitoring could inform strategies to reduce ocular surface complications in long-term glaucoma treatment.