In the US, age-related macular degeneration (AMD) is the leading cause of irreversible blindness in adults older than 50 years. As the older adult population increases worldwide, there is a growing economic burden of AMD.¹ Currently, there are no efficacious preventive measures for AMD development or available treatments for the nonexudative form, which accounts for 90% of cases.

Progress in microbiome research has accelerated in recent years. Through the use of 16S rRNA assays and other genomic sequencing techniques, researchers have provided new insights about the communities of microorganisms that inhabit human and animal hosts. There is mounting evidence about the importance of these ‘microbiotas’ in a wide variety of disease states, suggesting potential targets for preventative and therapeutic interventions. Until recently, however, the microbiome received relatively little attention in ophthalmology. This review explores emerging research on the roles that ocular and extraocular microbiotas may play in the pathogenesis and treatment of ophthalmic diseases. These include diseases of the ocular surface as well as autoimmune uveitis, age-related macular degeneration, and primary open angle glaucoma. Many questions remain about the potential impacts of microbiome research on the diagnosis, treatment, and prevention of ophthalmic disease. In light of current findings, we suggest directions for future study as this exciting area of research continues to expand.Impact statement: This review describes a growing body of research on relationships between the microbiome and eye disease. Several groups have investigated the microbiota of the ocular surface; dysregulation of this delicate ecosystem has been associated with a variety of pro-inflammatory states. Other research has explored the effects of the gastrointestinal microbiota on ophthalmic diseases. Characterizing the ways these microbiotas influence ophthalmic homeostasis and pathogenesis may lead to research on new techniques for managing ophthalmic disease.

To investigate if there are differences in macular capillaries between black and white subjects using optical coherence tomography angiography (OCTA) and identify potential factors underlying the epidemiologically-based higher vulnerability of black populations to diabetic retinopathy (DR). This prospective, observational cross-sectional study included 93 eyes of 47 healthy subjects with no medical history and ocular history who self-identified as black or white and were matched for age, sex, refractive error, and image quality. Subjects underwent OCTA imaging (RTVue-XR Avanti) of the superficial (SCP) and deep (DCP) capillary plexuses and choriocapillaris. AngioAnalytics was used to analyze vessel density (VD) and choriocapillaris % blood flow area (BFA) in the 1mm-diameter fovea, parafovea, and 3mm-diameter circular area including the fovea and parafovea (3x3mm image). Foveal avascular zone (FAZ) was also analyzed. Linear mixed models were used to evaluate for differences between the study groups. Compared to the white subjects in this study, black subjects were found to have: lower foveal VD in the SCP (p<0.05); lower VD in the parafovea and in the 3x3mm image in the DCP (p<0.05); larger FAZ in SCP and DCP (p<0.05); and decreased choriocapillary BFA in the area underlying the fovea, parafovea, and 3x3mm image (p<0.05). In our study, our black subjects had decreased macular capillary vasculature compared to matched white subjects, even in early adulthood and the absence of any systemic or ocular conditions. To our knowledge, this is the first report showing that retinal and choriocapillary vascular differences may contribute to racial disparities in vulnerability to DR.

To examine outcomes of 23-gauge (23G) pars plana vitrectomy (PPV) for complex diabetic tractional retinal detachment (TRD) in Chicago’s Cook County Health and Hospitals System (CCHHS). This is a retrospective noncomparative study of diabetic TRD cases that underwent PPV at CCHHS. Primary retinal reattachment rate, visual function, and postoperative complications were analyzed. Sixty nine consecutive cases were included. Primary reattachment and final attachment were achieved in 68/69 eyes (98.6%). Secondary retinal detachment was noted in 1 eye (1.4%). Vitreous hemorrhage requiring repeat PPV developed in 5 eyes (7.2%) and reoperation due to other complications was required in 4/69 eyes (5.8%). Perfluoropropane (C₃F₈) gas tamponade was used in 91.3% of eyes and silicone oil in 8.7% of eyes. Mean LogMAR visual acuity significantly improved from 1.84 ± 0.61 to 0.93 ± 0.66, (P<0.0001). Vision was stabilized or improved in 66 eyes (95.7%). Visual acuity of 20/200 or better was achieved in 49/69 eyes (71.0%) and 20/50 or better in 16/69 eyes (23.2%). Even in patients with severe and advanced diabetic TRD pathology and unique demographics as seen in CCHHS, modern vitrectomy techniques can provide excellent anatomical and visual outcomes.

Studies have begun to reveal significant connections between the gut microbiome and various retinal diseases, including age-related macular degeneration (AMD). As critical supporting tissues of the retina, the retinal pigment epithelium (RPE) and underlying choroid play a critical role in retinal homeostasis and degeneration. However, the relationship between the microbiome and RPE/choroid remains poorly understood, particularly in animal models of AMD. In order to better elucidate this role, we performed high-throughput RNA sequencing of RPE/choroid tissue in germ-free (GF) and specific pathogen-free (SPF) mice. Furthermore, utilizing a specialized laser-induced choroidal neovascularization (CNV) model that we developed, we compared CNV size and inflammatory response between GF and SPF mice. After correction of raw data, 660 differentially expressed genes (DEGs) were identified, including those involved in angiogenesis regulation, scavenger and cytokine receptor activity, and inflammatory response—all of which have been implicated in AMD pathogenesis. Among lasered mice, the GF group showed significantly decreased CNV lesion size and microglial infiltration around CNV compared to the SPF group. Together, these findings provide evidence for a potential gut–RPE/choroidal axis as well as a correlation with neovascular features of AMD.