Table 1. Relevant studies that have been conducted on the role of the microbiome in ophthalmologic diseases since 2018.

AMD: age-related macular degeneration, HLA: human leukocyte antigen, POAG: primary open-angle glaucoma

Authors	Study type	Disease	Findings
Peng et al. (2024) [27]	Case-control	Retinal dystrophy (Leber congenital amaurosis due to CRB1 gene mutation)	Mechanism connecting the gut and the eye: the principle of bacterial translocation-dependent retinal degeneration has implications that go beyond inherited retinal dystrophies.
Zhao et al. (2024) [48]	Systematic review and meta-analysis	Diabetic retinopathy	Association between alterations in the gut microbiome in type 2 diabetes and the development and progression of diabetic retinopathy: this suggests that restoring the homeostasis of the gut microbiome could be a potential way to prevent or treat diabetic retinopathy.
Morandi et al. (2024) [28]	Case-control	HLA-B27-associated non-infectious anterior uveitis	The development of uveitis is influenced by functional and compositional alterations of the intestinal microbiome. An increase in specific gram-negative bacteria and lipopolysaccharides may play a role in triggering inflammation and aberrant immune response in the eye.
Zhang et al. (2023) [49]	Case-control	AMD	AMD patients had different gut microbiota compared with healthy controls, and pathophysiology might be linked to changes in gut-related metabolic pathways.
Liu et al. (2023) [50]	Mendelian randomization	AMD	The order Rhodospirillales influenced AMD risk based on the gut-retinal axis.
Mao et al. (2023) [51]	Mendelian randomization	AMD	Causal relationship with microbiome gut taxa, including the Eubacterium oxidoreducens group, Faecalibacterium, Ruminococcaceae UCG-011, Anaerotruncus, and Candidatus Soleaferrea. These strains have the potential to serve as novel biomarkers.
Goodman et al. (2023) [52]	Case-control	Dry eye	Differences in the composition of the gut microbiome were found in individuals with predominantly early markers of Sjögren's syndrome compared to controls.
Liu et al. (2022) [15]	Mendelian randomization	Diabetic retinopathy	There is a possible causal relationship between some taxa of the gut microbiome and diabetic retinopathy, highlighting the association of the "gut-retina" axis and offering new insights into the mechanism of diabetic retinopathy.
Tavakoli et al. (2022) [43]	Case-control	Dry eye	The application of probiotics and prebiotics could be effective in the treatment of dry eye disease and suggests a possible alternative treatment.
Kutsyr et al. (2021) [25]	Case-control	Retinal dystrophy (retinitis pigmentosa)	Alterations in morphology and function of the rd10 mouse, an animal model of retinitis pigmentosa, demonstrate for the first time that retinal degenerative changes in neuronal and glial cells that occur in RP are concomitant with relevant changes in the gut microbiome.
Gong et al. (2020) [36]	Case-control	POAG	The first study that focused on the gut microbiome profile and its association with serum metabolites in patients with POAG.
Ye et al. (2020) [31]	Cohort	Uveitis	Distinct signature of the gut microbiome in patients with Vogt-Koyanagi-Harada, and they showed an exacerbating effect of this gut microbiome in experimental autoimmune uveitis.
Kalyana Chakravarthy et al. (2018) [53]	Cohort	Uveitis	The first study that demonstrated dysbiosis in the intestinal bacterial communities of patients with uveitis compared to healthy human subjects from a South Indian population.