Association of Metabolic Syndrome With Glaucoma and Ocular Hypertension in a Midwest United States Population

Metabolic syndrome as an independent risk factor for glaucoma: a nationally representative study

BACKGROUND

Central insulin resistance contributes to glaucoma development. Given the close association between metabolic syndrome MetS and insulin resistance, this study aimed to determine whether MetS is associated with glaucoma risk.

METHODS

We analyzed data from 11,499 adults aged ≥ 19 years in the 2019-2021 Korean National Health and Nutrition Examination Survey and applied sampling weights to represent the general Korean population. Participants were classified into groups with or without MetS. Ocular hypertension (HTN) was defined as intraocular pressure > 21 mmHg. Primary open-angle glaucoma (POAG) was diagnosed based on the results of a visual field test and optical coherence tomography using the criteria published by the International Society for Geographic and Epidemiological Ophthalmology. We further divided POAG into normal tension (NTG) and POAG with ocular HTN. A spline curve was drawn to determine the dose-response relationship between the number of MetS components and risk of POAG. Odds ratios (ORs) with 95% confidence interval (CI) for POAG according to MetS status were estimated using weighted logistic regression analyses.

RESULTS

The prevalence of POAG was 5.7% and 3.5%, respectively, in groups with and without MetS. We identified a dose-response relationship between the number of MetS components and risk of POAG. Unadjusted ORs (95% CI) for POAG in the group with MetS was 1.85 (1.52-2.25), compared with those without MetS. The trends persisted in adjusted models. The fully-adjusted OR (95% CI) for POAG was 1.47 (1.04-2.09) in the group with MetS. Subgroup analysis revealed that a significant relationship remained only in the NTG group (fully adjusted OR, 1.50; 95% CI 1.05-2.15).

CONCLUSIONS

A comprehensive ophthalmological assessment should be considered for persons with MetS who are at increased risk of POAG, particularly NTG.

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.

Metabolic syndrome and its components are associated with non-arteritic anterior ischaemic optic neuropathy

PURPOSE

To determine whether metabolic syndrome (MetS) is a risk factor for various forms of optic neuropathy including non-arteritic anterior ischaemic optic neuropathy (NAION).

METHODS

This population-based analysis identified patients ≥40 years of age in Olmsted County, Minnesota, USA using the Rochester Epidemiology Project 2005-2018. Patients with MetS were identified if three or more of the five standard criteria for diagnosing MetS were present: systemic hypertension, hyperglycaemia, hypertriglyceridaemia, reduced high-density lipoprotein cholesterol (hypoalphalipoproteinaemia) and central adiposity defined by increased body mass index. Charts of patients identified as having an optic neuropathy were reviewed to record specific diagnoses and compared with patients without ocular pathology other than cataract. The odds ratio (OR) of association with MetS was calculated and adjusted for age, sex and race with multivariate analysis for the various optic neuropathies.

RESULTS

Patients with MetS were more likely to have an optic neuropathy than those without (OR 2.2, p<0.001). After adjusting for age, sex and race, the only optic neuropathy found to be significantly associated with MetS was NAION (OR 6.17, p=0.002). For patients with NAION, though each individual component of MetS was individually significantly associated with MetS, further analysis suggested that hypertriglyceridaemia, hypoalphalipoproteinaemia and hyperglycaemia were likely the key drivers in the overall significance between NAION and MetS.

CONCLUSION

Patients with MetS were more likely to have NAION. Further studies are needed to determine whether MetS is a modifiable risk factor for NAION.