In the news: New Research on Gut Microbiome & Eye Diseases

Imbalanced Microbiome & Ocular Diseases

The gut microbiome is increasingly recognized as a potential contributor to the development of immune-mediated conditions elsewhere in the body, such as the eye. Two recently published studies shed more light on the gut and ocular health connection.

The first study(1) links bacterial diversity in the GI tract with genetic alleles that make individuals more susceptible to age-related macular degeneration (AMD).

Researchers compared 85 cases of advanced AMD with 49 healthy, age-similar controls to investigate whether an intestinal microbial signature is associated with advanced AMD, and to investigate the impact of AREDS supplementation and genetic risk on AMD microbiota.

Exploratory analysis (PLS-DA) showed that gut microbiome composition was able to predict AMD with moderate confidence.

A higher AMD genetic risk score was associated with lower gut microbial diversity (P = 0.0086; Spearman r = —0.3), a finding confirmed by multiple linear regression with confounding covariates.

In contrast, AREDS supplementation was linked with increased gut bacterial diversity (coefficient, 2.64; P < 0.05).

In terms of bacterial species, proteobacteria and many differentially abundant genera (including Prevotella, Desulfovibrio, Oscillospira, and Rumino-coccaceae) were increased in AMD versus controls. Increased IgA-coating of gut bacteria in ARMS2 gene risk genotype was also noted in AMD patients.

The authors conclude that “the intestinal microbiome is able to predict advanced AMD. AREDS supplementation and genetic risk are crucial determinants of the AMD microbiome, which interacts with gut immunity by increasing IgA binding to certain bacteria. Understanding how the gut microbiome and its metabolites interact with gut immunity and host genetics will allow us to further investigate the microbiome to find potentially novel therapeutic targets in AMD.”

Review: Gut-Eye Axis in Eye Diseases

The objective of the second study(2) was to synthesize advances in the last five years (2020-2025) on how gut, oral, and ocular surface microbiota contribute to the following six eye diseases: dry eye disease, non-infectious uveitis, glaucoma, optic neuropathy, AMD, and diabetic retinopathy.

The investigators also evaluated the therapeutic potential of microbiome-based interventions.

They report that for all six eye diseases, dysbiosis (disturbed microbiome) was consistently characterized by depletion of anti-inflammatory bacterial types (e.g. Akkermansia, Ruminococaceae) and other bacterial producers of short chain fatty acids, as well as increased pro-inflammatory bacterial types (e.g. Proteobacteria, Staphylococcus).

These changes were associated with an array of adverse factors such as increased intestinal permeability and compounds such as systemic lipopolysaccharide, and regulatory T-cell imbalance.

As for interventions, they found that probiotics containing Lactobacillus or Bifidobacterium improved tear stability and reduced inflammation in preclinical and pilot studies, while high-fiber diets improved lesions in AMD and diabetic retinopathy.

The authors call for large, longitudinal trials testing microbiome-targeted strategies in eye diseases.

References

1. Dadgar N, et al. Age-related eye disease studies supplements and genetic risk score are crucial determinants of intestinal microbial alterations in advanced age-related macular degeneration. Ophthalmol Sci. 28;6(1):100920, 2026.
2. Wang C, et al. Review: The gut-eye axis in blinding eye diseases: microbiota-driven immune dysregulation and immunomodulatory therapies. Inter Ophthalmol. 29;46(1):57, 2025.