Metabolic syndrome as a risk factor for elevated intraocular pressure

Identification of the novel role of sterol regulatory element binding proteins (SREBPs) in mechanotransduction and intraocular pressure regulation

Trabecular meshwork (TM) cells are contractile and mechanosensitive, and they aid in maintaining intraocular pressure (IOP) homeostasis. Lipids are attributed to modulating TM contractility, with poor mechanistic understanding. In this study using human TM cells, we identify the mechanosensing role of the transcription factors sterol regulatory element binding proteins (SREBPs) involved in lipogenesis. By constitutively activating SREBPs and pharmacologically inactivating SREBPs, we have mechanistically deciphered the attributes of SREBPs in regulating the contractile properties of TM. The pharmacological inhibition of SREBPs by fatostatin and molecular inactivation of SREBPs ex vivo and in vivo, respectively, results in significant IOP lowering. As a proof of concept, fatostatin significantly decreased the SREBPs responsive genes and enzymes involved in lipogenic pathways as well as the levels of the phospholipid, cholesterol, and triglyceride. Further, we show that fatostatin mitigated actin polymerization machinery and stabilization, and decreased ECM synthesis and secretion. We thus postulate that lowering lipogenesis in the TM outflow pathway can hold the key to lowering IOP by modifying the TM biomechanics.

Association of Hypertriglyceridemia and Incident Glaucoma in a Rural Chinese Population: The Handan Eye Study

Purpose

The purpose of this paper was to investigate the association between baseline metabolic risk factors and incident glaucoma over a 5-year period in rural Chinese adults.

Methods

Population-based prospective cohort study. Participants aged 30 years and older without glaucoma at baseline who underwent comprehensive examinations at baseline and after a 5-year interval in the Handan Eye Study were enrolled. Incident glaucoma was defined as people without glaucoma in either eye at baseline that had developed glaucoma in at least one eye in the 5-year follow-up. Five metabolic syndrome components, mean blood pressure, fasting plasma glucose, total cholesterol, triglycerides (TGs), low density lipoprotein cholesterol, high-density lipoprotein cholesterol, and obesity, determined as body mass index ≥30 kg/m2 at baseline were considered as potential metabolic risk factors for incident glaucoma. Univariate and multivariate logistic regression analyses were carried out to determine baseline metabolic risk factors associated with incident glaucoma.

Results

A total of 5184 participants were included in our study. During the 5-year follow-up, incident glaucoma developed in 82 subjects. Age (odds ratio [OR] = 1.060, 95% confidence interval [CI] = 1.034, 1.086, P < 0.001) and TGs level (OR = 1.213, 95% CI = 1.030, 1.429, P = 0.021) were independently and positively associated with incident glaucoma.

Conclusions

Our study revealed that increased age and high TGs level, one of the baseline metabolic features, were independent risk factors for incident glaucoma. The data implied that the metabolic features be involved in the pathogenesis of glaucoma.

Translational Relevance

This study shed the light on that the TGs level was involved in the pathogenesis of glaucoma.

Association between hypertriglyceridemia and open angle glaucoma: A case report

Hypertriglyseridemia is a metabolic disorder that can cause vascular dysfucntion and be causally associated with glaucoma. Herein we present the case of a 16-year-old boy with hypertriglyseridemia with open-angle glaucoma.

Correlation between body mass index and ocular parameters

Purpose: To investigate the relationship between BMI and selected ocular parameters.

Subjects and methods: Fifty-three left eyes of normal weight subjects and 67 age-sex matched overweight subjects were studied. Inclusion criteria for the normal weight and overweight groups included BMI between 18.5–22.9 and 23.0–29.9 kg/m², respectively. Subjects with a history of systemic disease, ocular disease or surgery, or disability were excluded. All subjects underwent a medical history interview, arterial blood pressure, height, weight, waist circumference and hip circumference measurements, and BMI and waist-hip ratio calculation. The intraocular pressure (IOP) and anterior corneal curvature were measured by non-contact tonometry and corneal topography, respectively. Measurement of anterior and posterior segment parameters of the eye, including central corneal thickness, anterior chamber depth (ACD), anterior chamber angle, macular thickness (MT), ganglion cell thickness (GCT), retinal nerve fiber layer thickness, cup to disc ratio, and choroidal thickness was performed by enhanced depth-imaging optical coherence tomography.

Results: There was a positive correlation between ACD and BMI (Univariate analysis; β =0.198, P=0.030, Multivariate analysis; β =0.410, P=0.005) and between BMI and IOP (Univariate analysis; β =0.269, P=0.003). The IOP of the overweight group was found to be significantly higher than of the normal weight group (12.80±3.40 and 11.86±2.12 mm Hg, respectively, P=0.002). Also, there was a significant difference found between the GCT and the MT of the two groups (P=0.036 and 0.009, respectively).

Conclusion: It was found that BMI strongly correlated with ACD and IOP. Also, the degree of obesity was found to be a significant factor; therefore, the relationship between these ocular parameters and the severity of obesity should be further investigated.

The association of intraocular pressure with metabolic syndrome and its components: a Meta-analysis and systematic review

AIM

To perform a Meta-analysis to explore the correlation between metabolic syndrome and intraocular pressure (IOP).

METHODS

We searched PubMed and Embase in November 2017 for studies discussing the relationship between metabolic syndrome components and IOP in patients. Pearson correlation coefficients, odds ratios and standardized betas were extracted from inclusive studies. Heterogeneity and publication bias were checked.

RESULTS

Of 295 articles, 10 met inclusion criteria and provided sufficient data for Meta-analysis. Results showed a significant positive relation between metabolic syndrome and IOP (Z=0.47, 95%CI: 0.15-0.79, P=0.005). The five components [waist circumference, hypertriglyceridemia, high blood pressure, high fasting glucose and low high density lipoprotein (HDL)-cholesterol] of metabolic syndrome all showed positive correlation with IOP except the low HDL-cholesterol which had no statistical significance. The pooled Z was 0.08 (95%CI: 0.04-0.12), 0.16 (95%CI: 0.11-0.21), 0.16 (95%CI: 0.10-0.22), 0.30 (95%CI: 0.20-0.40) and 0.12 (95%CI: 0.08-0.16), respectively. Begg's test and Egger's test showed no evidence of significant publication bias of this Meta-analysis.

CONCLUSION

Our findings suggest that metabolic syndrome and its components are significantly associated with IOP, besides the HDL-cholesterol. This association may be used to control IOP by intervening the occurrence of metabolic syndrome.

The synergistic effect of inflammation and metabolic syndrome on intraocular pressure: A cross-sectional study

Intraocular pressure is associated with metabolic syndrome. C-reactive protein (CRP) is associated with cardiovascular disease, irrespective of the presence of metabolic syndrome. In this study, we examined the synergistic effect of CRP and metabolic syndrome on intraocular pressure.A total of 1041 subjects were included for data analyses in this cross-sectional study. Intraocular pressure was measured using a noncontact tonometer, and serum CRP levels were measured using a commercially available kit.The intraocular pressure was significantly higher in the subjects with metabolic syndrome than in those without (14.1 ± 3.0 vs 13.4 ± 3.0 mm Hg, P = .002). Furthermore, intraocular pressures significantly increased according to CRP tertiles (13.1 ± 3.0, 13.7 ± 3.0, and 13.8 ± 3.0 mm Hg from the lowest to highest tertile of CRP, respectively; P = .002). The highest intraocular pressure was observed in subjects with metabolic syndrome in the highest CRP tertile (P value for trend < .001). Multivariate linear regression analysis revealed that the influence of CRP was independent of metabolic syndrome and that high CRP levels were significantly associated with high intraocular pressure (95% confidence interval: 0.080-1.297, P = .027).In conclusion, systemic inflammation, reflected by serum CRP levels, is associated with high intraocular pressure in subjects with and without metabolic syndrome.

Triglycerides and Open Angle Glaucoma - A Meta-analysis with meta-regression

Although intraocular pressure is the main the risk factor for the development of glaucoma, other risk factors such as vascular dysfunction might play an additional pathogenic role. Hypertriglyceridemia, which may lead to vascular dysfunction, has been implicated in the development of glaucoma. The objective of this meta-analysis was to investigate the association of triglyceride levels with the risk of glaucoma in case-control studies. Seventeen case-control studies were included investigating the difference in triglyceride levels in patients with glaucoma (N = 1 391) compared to subjects without glaucoma (N = 25 575). In random effects meta-analysis, the pooled mean triglyceride level across all studies and patients with and without glaucoma was 132.9 mg/dL (95%CI: 124.0-141.7). Patients with glaucoma had significantly higher mean triglyceride levels than patients without glaucoma (absolute difference = 14.2 mg/dL, 95%CI: 5.8-22.5, p < 0.0001). A considerable amount of heterogeneity of included studies was observed (I2 = 66.2%, heterogeneity χ2 = 47.4 on 16 degrees of freedom, p < 0.0001). In conclusion, this meta-analysis of case-control studies found that patients with glaucoma had higher mean triglyceride levels than patients without glaucoma. This finding is consistent with the concept that hypertriglyceridemia represents an additional risk factor for glaucoma. Whether this association is causal and/or might be modified by glaucoma medications remains to be investigated.

The association between intraocular pressure and different combination of metabolic syndrome components

BACKGROUND

Although the association between metabolic syndrome and intraocular pressure is well known, the relationship between the intraocular pressure and different combination of the components of metabolic syndrome has not been actively researched yet. The study aimed to investigate the relationship between the intraocular pressure and metabolic syndrome components with their different combinations.

METHODS

Thirty-one thousand two hundred seventy one healthy people aged 19-79 who attended a community hospital for a health check-up between January 2011 and December 2013 were enrolled in the study. Subjects with a history of intraocular disease, at least in one eye and those receiving medical treatment for glaucoma were excluded. Metabolic syndrome was diagnosed following the criteria defined in Circulation 2009.

RESULTS

Subjects with combination of three metabolic syndrome components of triglycerides, abdominal obesity, and fasting glucose had the highest intraocular pressure. And subjects with the combination of four components of blood pressure, high-density lipoproteins, triglycerides, fasting glucose had a significantly higher intraocular pressure than ones with the combination of all five metabolic syndrome components.

CONCLUSIONS

The difference in the risk of high intraocular pressure according to the different combination of the metabolic syndrome components could be confirmed. If additional follow-up studies are conducted, the findings can be used as an indicator for predicting intraocular pressure increases in patients with metabolic syndrome.

Evaluation of Anterior Segment Parameters in Obesity

PURPOSE

To investigate anterior segment parameters in obese patients in comparison to healthy individuals.

METHODS

Thirty-four obese subjects and 34 age-sex-matched healthy subjects were enrolled in this prospective cross-sectional study. Ophthalmological examinations including intraocular pressure (IOP), central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and axial length (AL) measurements were performed on each subject. Height and weight of all subjects were recorded and body mass index (BMI) was calculated.

RESULTS

IOP was significantly higher in the obese group (p = 0.003). The mean ACD in obese subjects was significantly lower than that in control subjects (p = 0.036). AL, ACV, ACA and CCT were not significantly different between the groups. There was a positive correlation between BMI and IOP (r = 0.404, p < 0.001). ACD and ACA were negatively correlated with BMI.

CONCLUSIONS

IOP was significantly higher and ACD was significantly lower in obese subjects. AL, ACV, ACA and CCT were not significantly different between the groups. The impact of obesity on anterior chamber parameters should be further investigated.