Gut-ocular axis: An emerging strategy to treat ocular diseases

Table 2 Current level of evidence for each major ocular condition

Ocular disease	Animal studies	Human observational studies	Clinical trials/meta-analyses
Dry eye disease	Multiple murine models (germ-free, antibiotic-treated)[10]	Cross-sectional and cohort studies (Sjögren and non-Sjögren)[20]	Limited; pilot probiotic trials
Uveitis	Extensive (EAU models, gnotobiotic mice)[8,9]	Case-control studies (Behçet, HLA-B27)[31]	No published RCTs; case series with FMT
Glaucoma	Murine models (commensal T-cell priming)	Preliminary cross-sectional studies[10,21]	None published to date
Diabetic retinopathy	Rodent models of type 1 and type 2 diabetes[28]	Cross-sectional gut microbiome profiling[12]	No dedicated ocular endpoint trials
Age-related macular degeneration	High-fat diet murine models[25,26]	Case-control gut microbiome studies[14,22]	No published RCTs

HLA: Human leukocyte antigen; RCT: Randomized controlled trial; FMT: Fecal microbiota transplantation.