Association Between Body Mass Index and Primary Open Angle Glaucoma in Three Cohorts

Low Body Mass Index Poses Greater Risk of Primary Open-Angle Glaucoma in African Ancestry Individuals

PURPOSE

Investigate the relationship between body mass index (BMI) and primary open-angle glaucoma (POAG) in an African ancestry cohort from the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study.

DESIGN

Retrospective, cross-sectional "case-control" comparison study.

METHODS

A total of 6,634 POAAGG study subjects were eligible: 2,977 cases and 3,657 controls. Ocular and demographic data were collected from on-site exams, standardized interviews, and electronic medical records. BMI was calculated: weight(kg)/height(m)2, and categorized as low (<18.5), moderate (18.5-24.9), high (25.0-29.9), or very high (≥30). Structural and functional POAG progression were assessed by annual rate of change in retinal nerve fiber layer thickness and visual field mean deviation, respectively, using a linear mixed-effects model. Regression analyses evaluated associations of BMI with POAG status, phenotype, and progression.

RESULTS

Lower BMI was associated with increased POAG risk (aOR[95% confidence interval], 1.02 [1.007,1.023] per kg/m2 decrease in BMI, p = .0003). In cases, low BMI was associated with larger cup-to-disc ratio (p = .007) and worse visual acuity (p = .04). Fast functional POAG progressors had a significantly lower mean BMI than slow progressors (25.7 vs. 30.0 kg/m2, p = .04).

CONCLUSIONS

In this African ancestry cohort, low BMI was associated with increased POAG risk. POAG cases with low BMI were more likely to have larger cup-to-disc ratios, worse visual acuity, and faster functional progression, indicating more severe glaucoma.

Association between oxidative balance score and glaucoma in the National Health and Nutrition Examination Survey

Objective

To investigate the association between Oxidative Balance Score (OBS) and glaucoma risk.

Methods

Using data from the National Health and Nutrition Examination Survey (2005-2008), we analyzed 2,615 participants aged ≥40 years. OBS was calculated from 15 antioxidant and 5 pro-oxidant components, including dietary nutrients and lifestyle factors. Glaucoma was identified through self-reported diagnosis and retinal imaging. Survey-weighted logistic regression and restricted cubic splines (RCS) were used to assess associations.

Results

Higher OBS was associated with lower glaucoma risk (adjusted OR = 0.97, 95% CI: 0.94-1.00). Participants in the highest OBS quartile showed 51% lower odds of glaucoma compared to the lowest quartile (adjusted OR = 0.49, 95% CI: 0.27-0.90). The protective effect was more pronounced among middle-aged adults (40-60 years; OR = 0.90, 95% CI: 0.86-0.95) and males (OR = 0.93, 95% CI: 0.90-0.97).

Conclusion

Higher OBS were associated with lower glaucoma prevalence, particularly among middle-aged adults and males, suggesting potential benefits of maintaining oxidative balance in glaucoma prevention.

Nationwide cohort study of primary open angle glaucoma risk and cardiovascular factors among in Korean glaucoma suspects

This retrospective study investigated the risk of primary open-angle glaucoma (POAG) among individuals identified as glaucoma suspects and examined associated cardiovascular risk factors. We conducted a longitudinal, nationwide cohort study using data from the Korean National Health Insurance Service (KNHIS) and included 362,285 participants aged ≥ 40 years from the Korean National Health Screening Program (NHSP) without pre-existing POAG in 2009 and 2010. Of these, glaucoma suspects (n = 32,220) were defined as individuals with at least two recorded instances of the KCD code H400 for glaucoma suspect and no prior antiglaucoma medication prescriptions before health screening. The primary outcome was the diagnosis of POAG and the prescription of antiglaucoma medications. Over a 6-year follow-up, 4.92% of glaucoma suspects developed POAG. Through multivariate Cox regression analysis, glaucoma suspects with diabetes, hypertension, dyslipidemia, or coronary heart disease exhibited a greater risk of conversion to POAG than those without these comorbidities ([HR, 1.354; 95%CI, 1.201 to 1.527] for diabetes, [HR, 1.139; 95%CI, 1.019 to 1.273] for systemic hypertension, [HR, 1.128; 95%CI, 1.013 to 1.26] for dyslipidemia, [HR, 1.124, 95%CI, 1.007 to 1.254] for coronary heart disease).This nationwide study observed that among glaucoma suspects, having cardiovascular risk factors/disease was associated with higher risk of developing POAG.

Social history and glaucoma progression: the effect of body mass index, tobacco and alcohol consumption on the rates of structural change in patients with glaucoma

BACKGROUND/AIMS

Although obesity, tobacco and alcohol consumption were linked to the progression of numerous chronic diseases, an association of these social history aspects with glaucoma progression is not yet determined. This study aims to investigate the effect of body mass index (BMI) and history of tobacco and alcohol use on the rates of retinal nerve fibre layer (RNFL) change over time in glaucoma patients.

METHODS

2839 eyes of 1584 patients with glaucoma from the Duke Ophthalmic Registry were included. Patients had at least two spectral-domain optical coherency tomography (SD-OCT) tests over a minimum 6-month follow-up. Self-reported history of alcohol and tobacco consumption was extracted from electronic health records and mean BMI was calculated. Univariable and multivariable linear mixed models were used to determine the effect of each parameter on RNFL change over time.

RESULTS

Mean follow-up time was 4.7±2.1 years, with 5.1±2.2 SD-OCT tests per eye. 43% and 54% of eyes had tobacco or alcohol consumption history, respectively, and 34% were classified as obese. Higher BMI had a protective effect on glaucoma progression (0.014 µm/year slower per each 1 kg/m2 higher; p=0.011). Tobacco and alcohol consumption were not significantly associated with RNFL change rates (p=0.473 and p=0.471, respectively). Underweight subjects presented significantly faster rates of structural loss (-0.768 µm/year; p=0.002) compared with normal weight.

CONCLUSIONS

In a large clinical population with glaucoma, habits of tobacco and alcohol consumption showed no significant effect on the rates of RNFL change. Higher BMI was significantly associated with slower rates of RNFL loss.

Association of obesity and metabolic syndrome with incident primary open angle glaucoma in the UK Biobank

BACKGROUND

We sought to investigate the association between obesity, metabolic syndrome, and metabolic health with incident primary open-angle glaucoma (POAG).

METHODS

We included 103 249 UK Biobank participants without previously diagnosed glaucoma or glaucoma-related procedures at enrolment. The primary outcome was POAG identified from diagnostic coding via linked hospital inpatient and primary care data. We used multivariable Cox regression to evaluate the association of body mass index (BMI), and the interaction with metabolic syndrome (MetS) and a novel definition of metabolic health status with incident POAG. BMI was modelled as a time-varying coefficient. Multivariable analysis was adjusted for age, sex, ethnicity, intraocular pressure, spherical equivalent, polygenic risk score and stratified by the presence of primary care data.

RESULTS

There were 647 events of incident POAG over 464 117 580 person-years and a mean follow-up of 12.6 years. At baseline (time = 0), each one unit increase in BMI was associated with a 9% lower hazard of incident glaucoma (HR 0.91, CI 0.86-0.97, p = 0.0066). Further, compared to a normal BMI range of 18.5-24 kg/m2, a BMI ≥30 kg/m2 was associated with a 65% relative hazard reduction (HR 0.35, CI 0.16-0.80, p = 0.012). There was no significant interaction between BMI and metabolic syndrome or metabolic health (all p > 0.05).

CONCLUSION

The effect of BMI on the risk of incident POAG varied with time. Higher BMI was associated with a decreased risk of incident POAG in this large prospective cohort. There was no significant association with systemic metabolic health.

Fecal microbiota transplantation for glaucoma; a potential emerging treatment strategy

Glaucoma is the primary cause of irreversible blindness globally. Different glaucoma subtypes are identified by their underlying mechanisms, and treatment options differ by its pathogenesis. Current management includes topical medications to lower intraocular pressure and surgical procedures like trabeculoplasty and glaucoma drainage implants. Fecal microbiota transplantation (FMT) is an almost effective and safe treatment option for recurrent Clostridium difficile infection. The relationship between bacterial populations, metabolites, and inflammatory pathways in retinal diseases indicates possible therapeutic strategies. Thus, incorporating host microbiota-based therapies could offer an additional treatment option for glaucoma patients. Here, we propose that combining FMT with standard glaucoma treatments may benefit those affected by this condition. Also, the potential safety, efficacy, cost-effectiveness and clinical applications are discussed.

The association between airborne particulate matter (PM2.5) exposure level and primary open-angle glaucoma

The eye is vulnerable to the adverse effects of air pollution. Previous experimental study found that fine particulate matter (PM2.5) had a direct toxic effect on intraocular tissues. However, clinical evidence for the impact of air pollutants exposure on functional and structural changes in glaucoma remains scarce. A total of 120 patients with primary open-angle glaucoma (POAG) who met the inclusion criteria were included in this retrospective study. The standardized ophthalmic examination, such as intraocular pressure (IOP), visual field, optical coherence tomography, and comprehensive physical examination, were performed. The air pollution data, including PM2.5 concentration and air quality index (AQI), were collected. PM2.5 and AQI for the day of the medical examination, as well as one month, and three months before the medical examination date, were investigated. In our results, higher average exposure levels for one-month and three-month, were associated with increased IOP (r=0.229, P=0.013; r=0.204, P=0.028, respectively) and decreased visual field mean sensitivity (MS) (r=-0.212, P=0.037; r=-0.305, P=0.002, respectively). PM2.5 concentrations for the day of the medical examination was not significantly associated with ocular parameters. In multiple linear regression analysis adjusted for demographic and clinical factors, higher PM2.5 exposure for one month was associated with elevated IOP (P=0.040, β=0.173, 95 %CI=0.008-0.337). We also found an association between PM2.5 and MS (one-month exposure: β=-0.160, P=0.029; three-month exposure: β=-0.238, P=0.002). The logistic regression analysis found that three-month average PM2.5 exposure level was significantly associated with the disease severity (β=0.043, P=0.025, 95 %CI=1.005-1.084). In conclusion, this study is the first to investigate the relationship between air pollution and detailed ocular parameters of POAG patients in Shanghai over a three-year period, and to explore the effects of different exposure times of PM2.5 on glaucoma. This study found that PM2.5 exposure was correlated with elevated IOP and decreased MS. The one-month PM2.5 exposure level had the most significant effects on IOP. The three-month PM2.5 exposure level was an independent risk factor for POAG severity. Current evidence suggests there may be an association between PM2.5 exposure and POAG.

Evaluating the impact of caloric restriction, body mass index and exercise on primary open-angle glaucoma: A review

This literature review evaluates any possible links between primary open-angle glaucoma (POAG) and caloric restriction (CR), body mass index (BMI), and exercise, aiming to map the extent of the literature. Its primary objective is to recognise the nature and breadth of research evidence, identify possible gaps in these topics and develop future studies. The databases searched were MEDLINE (PudMed), Scopus and ScienceDirect, in April 2023 for articles published in English, with no date restriction. A total of 447 search results were retrieved. Of these, 73 were related to CR, 249 to BMI, and 125 to exercise. Records identified included systematic reviews, meta-analyses, randomised controlled trials, cohort studies and animal studies. CR has been shown to halt the degeneration of retinal ganglion cells and protect against various glaucomatous processes in animal models. Low BMI has been shown to be associated with an increased risk of POAG and a faster rate of visual field deterioration in POAG. However, the association between high BMI and POAG is not consistent. Exercise has been shown to cause mechanical, vascular, and neurobiological changes affecting the pathophysiology of POAG. The present review helps identify key characteristics and factors relating to the impacts of CR, BMI, or exercise on POAG.

Big data in visual field testing for glaucoma

Recent technological advancements and the advent of ever-growing databases in health care have fueled the emergence of "big data" analytics. Big data has the potential to revolutionize health care, particularly ophthalmology, given the data-intensive nature of the medical specialty. As one of the leading causes of irreversible blindness worldwide, glaucoma is an ocular disease that receives significant interest for developing innovations in eye care. Among the most vital sources of data in glaucoma is visual field (VF) testing, which stands as a cornerstone for diagnosing and managing the disease. The expanding accessibility of large VF databases has led to a surge in studies investigating various applications of big data analytics in glaucoma. In this study, we review the use of big data for evaluating the reliability of VF tests, gaining insights into real-world clinical practices and outcomes, understanding new disease associations and risk factors, characterizing the patterns of VF loss, defining the structure-function relationship of glaucoma, enhancing early diagnosis or earlier detection of progression, informing clinical decisions, and improving clinical trials. Equally important, we discuss current challenges in big data analytics and future directions for improvement.

Evaluation of the Observational Associations and Shared Genetics Between Glaucoma With Depression and Anxiety

Purpose

Glaucoma, a leading cause of blindness worldwide, is suspected to exhibit a notable association with psychological disturbances. This study aimed to investigate epidemiological associations and explore shared genetic architecture between glaucoma and mental traits, including depression and anxiety.

Methods

Multivariable logistic regression and Cox proportional hazards regression models were employed to investigate longitudinal associations based on UK Biobank. A stepwise approach was used to explore the shared genetic architecture. First, linkage disequilibrium score regression inferred global genetic correlations. Second, MiXeR analysis quantified the number of shared causal variants. Third, specific shared loci were detected through conditional/conjunctional false discovery rate (condFDR/conjFDR) analysis and characterized for biological insights. Finally, two-sample Mendelian randomization (MR) was conducted to investigate bidirectional causal associations.

Results

Glaucoma was significantly associated with elevated risks of hospitalized depression (hazard ratio [HR] = 1.54; 95% confidence interval [CI], 1.01-2.34) and anxiety (HR = 2.61; 95% CI, 1.70-4.01) compared to healthy controls. Despite the absence of global genetic correlations, MiXeR analysis revealed 300 variants shared between glaucoma and depression, and 500 variants shared between glaucoma and anxiety. Subsequent condFDR/conjFDR analysis discovered 906 single-nucleotide polymorphisms (SNPs) jointly associated with glaucoma and depression and two associated with glaucoma and anxiety. The MR analysis did not support robust causal associations but indicated the existence of pleiotropic genetic variants influencing both glaucoma and depression.

Conclusions

Our study enhances the existing epidemiological evidence and underscores the polygenic overlap between glaucoma and mental traits. This observation suggests a correlation shaped by pleiotropic genetic variants rather than being indicative of direct causal relationships.

Potentially compromised systemic and local lactate metabolic balance in glaucoma, which could increase retinal glucose and glutamate concentrations

To investigate the association between lactate metabolism and glaucoma, we conducted a multi-institutional cross-sectional clinical study and a retinal metabolomic analysis of mice with elevated intraocular pressure (IOP) induced by intracameral microbead injection. We compared lactate concentrations in serum and aqueous humor in age-matched 64 patients each with primary open-angle glaucoma (POAG) and cataract. Neither serum nor aqueous humor lactate concentrations differed between the two groups. Multiple regression analysis revealed that only body mass index showed a significant positive correlation with serum and aqueous humor lactate concentration in POAG patients (rs = 0.376, P = 0.002, and rs = 0.333, P = 0.007, respectively), but not in cataract patients. L-Lactic acid was one of the most abundantly detected metabolites in mouse retinas with gas chromatography and mass spectrometry, but there were no significant differences among control, 2-week, and 4-week IOP elevation groups. After 4 weeks of elevated IOP, D-glucose and L-glutamic acid ranked as the top two for a change in raised concentration, roughly sevenfold and threefold, respectively (ANOVA, P = 0.004; Tukey-Kramer, P < 0.05). Glaucoma may disrupt the systemic and intraocular lactate metabolic homeostasis, with a compensatory rise in glucose and glutamate in the retina.

Change of Intraocular Pressure Over 5 Years and its Relationship to Cardiovascular Parameters: Results From the Gutenberg Health Study

Purpose

To investigate the longitudinal change in intraocular pressure (IOP) over 5 years and its relationship with cardiovascular parameters in a population-based sample in Germany.

Methods

The Gutenberg Health Study is a prospective, observational, single-center cohort study. The sample was equally stratified for sex, residence, and age decade. IOP was measured with noncontact tonometry at baseline and at 5-year follow-up. Cardiovascular parameters, including body mass index (BMI), systolic blood pressure, and diabetes status, were assessed. Participants without IOP measurement at one time point, who were taking IOP-lowering medications, or who had ophthalmic surgery during the 5-year follow-up interval were excluded, as well as those with glaucoma diagnosis. Univariable and multivariable linear regression analyses were conducted.

Results

This analysis included 9633 participants (48.9% female). The mean IOP increased from 14.04 ± 2.78 mmHg at baseline to 14.77 ± 2.92 mmHg at 5-year follow-up (P < 0.001). In multivariable linear regression analyses, an increase in BMI was associated with an increase in IOP over time (P < 0.001), whereas a higher baseline BMI was associated with a lower IOP change (P < 0.001). Higher age and male sex were associated with higher IOP change (P < 0.001). A change in systolic blood pressure was associated with IOP change, whereas baseline systolic blood pressure and diabetes status were not associated.

Conclusions

This population-based study found a relationship between IOP change over 5 years and BMI and systolic blood pressure change, respectively. These findings suggest the importance of monitoring cardiovascular risk factors in IOP management.

The role of the microbiota in glaucoma

Glaucoma is a common irreversible vision loss disorder because of the gradual loss of retinal ganglion cells (RGCs) and the optic nerve axons. Major risk factors include elder age and high intraocular pressure (IOP). However, high IOP is neither necessary nor sufficient to cause glaucoma. Some non-IOP signaling cascades can mediate RGC degeneration. In addition, gender, diet, obesity, depression, or anxiety also contribute to the development of glaucoma. Understanding the mechanism of glaucoma development is crucial for timely diagnosis and establishing new strategies to improve current IOP-reducing therapies. The microbiota exerts a marked influence on the human body during homeostasis and disease. Many glaucoma patients have abnormal compositions of the microbiota (dysbiosis) in multiple locations, including the ocular surface, intraocular cavity, oral cavity, stomach, and gut. Here, we discuss findings in the last ten years or more about the microbiota and metabolite changes in animal models, patients with three risk factors (aging, obesity, and depression), and glaucoma patients. Antigenic mimicry and heat stress protein (HSP)-specific T-cell infiltration in the retina may be responsible for commensal microbes contributing to glaucomatous RGC damage. LPS-TLR4 pathway may be the primary mechanism of oral and ocular surface dysbiosis affecting glaucoma. Microbe-derived metabolites may also affect glaucoma pathogenesis. Homocysteine accumulation, inflammatory factor release, and direct dissemination may link gastric H. pylori infection and anterior chamber viral infection (such as cytomegalovirus) to glaucoma. Potential therapeutic protocols targeting microbiota include antibiotics, modified diet, and stool transplant. Later investigations will uncover the underlying molecular mechanism connecting dysbiosis to glaucoma and its clinical applications in glaucoma management.

Cannabis use and the risk of primary open-angle glaucoma: a Mendelian randomization study

Several observational studies have investigated the association between cannabis use and intraocular pressure, but its association with primary open-angle glaucoma (POAG) remains unclear. In this study, we leveraged human genetic data to assess through Mendelian randomization (MR) whether cannabis use affects POAG. We used five single-nucleotide polymorphisms (SNPs) associated with lifetime cannabis use (P-value < 5 × 10-8) from a genome-wide association study (GWAS) (N = 184,765) by the International Cannabis Consortium, 23andMe, and UK Biobank and eleven SNPs associated with cannabis use disorder (P-value < 5 × 10-7) from a GWAS meta-analysis of (17,068 cases and 357,219 controls of European descent) from Psychiatric Genomics Consortium Substance Use Disorders working group, Lundbeck Foundation Initiative for Integrative Psychiatric Research, and deCode. We associated the selected five SNPs from the GWAS of lifetime cannabis use and the eleven SNPs from the GWAS of cannabis use disorder, with the largest to date GWAS meta-analysis of POAG (16,677 cases and 199,580 controls). MR analysis suggested no evidence for a causal association of lifetime cannabis use and cannabis use disorder with POAG (odds ratio (OR) of outcome per doubling of the odds of exposure (95% confidence interval): 1.04 (0.88; 1.23) for lifetime cannabis use and 0.97 (0.92; 1.03) for cannabis use disorder). Sensitivity analyses to address pleiotropy and weak instrument bias yielded similar estimates to the primary analysis. In conclusion, our results do not support a causal association between cannabis use and POAG.

Differences in Factors Associated With Glaucoma Progression With Lower Normal Intraocular Pressure in Superior and Inferior Halves of the Optic Nerve Head

Purpose

The purpose of this study was to investigate risk factors for progression in the superior and inferior hemi-visual fields (hemi-VFs) and the corresponding hemi-disc/retinas in eyes with normal tension glaucoma (NTG).

Methods

A 5-year prospective follow-up of 90 patients with NTG with untreated intraocular pressure (IOP) consistently ≤ 15 mm Hg was conducted. The IOP and Humphrey Perimeter measurements and disc/retina stereo-photographs were taken every 3 and 6 months, respectively. Risk factors for progression in the superior and inferior hemi-VFs and in the superior and inferior hemi-disc/retinas were investigated.

Results

The mean total deviation values decreased at -0.50 ± 0.76 and -0.13 ± 0.34 dB/year in the superior and inferior hemi-VFs, respectively (P < 0.001). In the superior hemi-VF, the risk factor for faster progression was greater long-term IOP fluctuation (P = 0.022). In the inferior hemi-VF, the risk factors were disc hemorrhage (DH), greater myopic refraction, body mass index (BMI), and vertical cup-to-disc ratio (v-C/D; P < 0.05). The progression probability was 47.7 ± 6.0 and 17.7 ± 4.7% at 5 years in the superior and inferior hemi-disc/retinas respectively (P < 0.001), and DH was a risk factor for progression in both (P = 0.001).

Conclusions

In NTG eyes, greater BMI, myopia, and v-C/D are characteristic risk factors for faster progression in the superior half of the optic nerve head (ONH), whereas long-term IOP fluctuation is the significant risk factor in the inferior half of the ONH, whereas DH is a risk factor in both.

Translational Relevance

Different risk factors were identified in superior and inferior hemifields in NTG eyes.

Causal factors in primary open angle glaucoma: a phenome-wide Mendelian randomisation study

Primary open angle glaucoma (POAG) is a chronic, adult-onset optic neuropathy associated with characteristic optic disc and/or visual field changes. With a view to identifying modifiable risk factors for this common neurodegenerative condition, we performed a 'phenome-wide' univariable Mendelian randomisation (MR) study that involved analysing the relationship between 9661 traits and POAG. Utilised analytical approaches included weighted mode based estimation, the weighted median method, the MR Egger method and the inverse variance weighted (IVW) approach. Eleven traits related to POAG risk were identified including: serum levels of the angiopoietin-1 receptor (OR [odds ratio] = 1.11, IVW p = 2.34E-06) and the cadherin 5 protein (OR = 1.06, IVW p = 1.31E-06); intraocular pressure (OR = 2.46-3.79, IVW p = 8.94E-44-3.00E-27); diabetes (OR = 5.17, beta = 1.64, IVW p = 9.68E-04); and waist circumference (OR = 0.79, IVW p = 1.66E-05). Future research focussing on the effects of adiposity, cadherin 5 and angiopoietin-1 receptor on POAG development and progression is expected to provide key insights that might inform the provision of lifestyle modification advice and/or the development of novel therapies.

Phenotypic and Genetic Links between Body Fat Measurements and Primary Open-Angle Glaucoma

The phenotypic and genetic links between body fat phenotypes and primary open-angle glaucoma (POAG) are unclear. We conducted a meta-analysis of relevant longitudinal epidemiological studies to evaluate the phenotypic link. To identify genetic links, we performed genetic correlation analysis and pleiotropy analysis of genome-wide association study summary statistics datasets of POAG, intraocular pressure (IOP), vertical cup-to-disc ratio, obesity, body mass index (BMI), and waist-to-hip ratio. In the meta-analysis, we first established that obese and underweight populations have a significantly higher risk of POAG using longitudinal data. We also discovered positive genetic correlations between POAG and BMI and obesity phenotypes. Finally, we identified over 20 genomic loci jointly associated with POAG/IOP and BMI. Among them, the genes loci CADM2, RP3-335N17.2, RP11-793K1.1, RPS17P5, and CASC20 showed the lowest false discovery rate. These findings support the connection between body fat phenotypes and POAG. The newly identified genomic loci and genes render further functional investigation.

Microbiome Dysbiosis: A Pathological Mechanism at the Intersection of Obesity and Glaucoma

The rate at which obesity is becoming an epidemic in many countries is alarming. Obese individuals have a high risk of developing elevated intraocular pressure and glaucoma. Additionally, glaucoma is a disease of epidemic proportions. It is characterized by neurodegeneration and neuroinflammation with optic neuropathy and the death of retinal ganglion cells (RGC). On the other hand, there is growing interest in microbiome dysbiosis, particularly in the gut, which has been widely acknowledged to play a prominent role in the etiology of metabolic illnesses such as obesity. Recently, studies have begun to highlight the fact that microbiome dysbiosis could play a critical role in the onset and progression of several neurodegenerative diseases, as well as in the development and progression of several ocular disorders. In obese individuals, gut microbiome dysbiosis can induce endotoxemia and systemic inflammation by causing intestinal barrier malfunction. As a result, bacteria and their metabolites could be delivered via the bloodstream or mesenteric lymphatic vessels to ocular regions at the level of the retina and optic nerve, causing tissue degeneration and neuroinflammation. Nowadays, there is preliminary evidence for the existence of brain and intraocular microbiomes. The altered microbiome of the gut could perturb the resident brain-ocular microbiome ecosystem which, in turn, could exacerbate the local inflammation. All these processes, finally, could lead to the death of RGC and neurodegeneration. The purpose of this literature review is to explore the recent evidence on the role of gut microbiome dysbiosis and related inflammation as common mechanisms underlying obesity and glaucoma.