Elevated intraocular pressure is associated with insulin resistance and metabolic syndrome

Influence of meteorological factors on intraocular pressure variability using a large-scale cohort

The effects of meteorological conditions on IOP using a large-scale health examination cohort were investigated. There were a total of 811,854 measurements from 126,630 eyes of 63,839 subjects in 9 years from a health checkup cohort followed up annually for age, sex, body height, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), and IOP. The effects of these variables and the meteorological data of daily average temperature (TP), daily average local atmospheric pressure (AP), daily average volumetric humidity (VH), and daily amount of rainfall (RF) on the day of IOP measurement on IOP were investigated. Several variables were significantly associated with IOP, including sex, age, body height, BMI, SBP, DBP, average TP, average AP, average VH, RF, white blood cell count, red blood cell count, hemoglobin, aspartate aminotransferase, alanine aminotransferase, guanosine triphosphate, calcium, and HbA1c. This study indicated a correlation between meteorological factors and IOP. Higher AP and RF were associated with elevated IOP, whereas higher TP and VH were associated with decreased IOP.

Relationships between Frailty and the Risk of Glaucoma in Middle-aged and Older Adults

PURPOSE

Increased frailty in older individuals increases health risks, but its relationship with glaucoma, the leading cause of irreversible blindness in middle-aged and older adults, is unclear. We investigated the association between frailty and glaucoma in a large-scale representative sample and explored possible causal relationships.

DESIGN

Combined cross-sectional and Mendelian randomization (MR) study.

PARTICIPANTS

In the cross-sectional analysis, we included 5744 participants of the US National Health and Nutrition Examination Surveys 2005-2008 aged ≥40. For the MR analysis, frailty genome-wide association study (GWAS) data were sourced from a UK Biobank and TwinGen meta-analysis, and GWAS data on glaucoma subtypes were derived from FinnGen.

METHODS

According to the 49-item frailty index, we classified participants into nonfrail (≤0.10), prefrail (0.10-0.21), and frail (>0.21) groups. Using survey-weighted logistic regression models adjusted for multiple covariates, we explored the association between frailty and glaucoma. We further assessed causation using MR.

MAIN OUTCOME MEASURES

The associations between different levels of frailty (nonfrail, prefrail, and frail) and glaucoma, as well as causal relationships between genetically predicted frailty and various subtypes of glaucoma (primary open-angle glaucoma, primary angle-closure glaucoma, normotensive glaucoma, exfoliation glaucoma, and suspected glaucoma).

RESULTS

After adjusting for covariates, higher frailty levels were significantly associated with glaucoma in frail individuals (odds ratio [OR]=1.83, 95% confidence interval [CI]=1.05-3.19, P=0.036) but not prefrail (OR=1.90, 95% CI=0.99-3.64, P=0.052). The association was significantly stronger among male participants (P interaction=0.042). The variation in the association between frailty and glaucoma did not reach statistical significance across age groups (P interaction=0.575) or race groups (P interaction=0.092). MR revealed that genetically predicted frailty was linked to greater risks for primary open-angle glaucoma (OR=1.67, 95% CI=1.24-2.25, P=0.001), primary angle-closure glaucoma (OR=2.78, 95% CI=1.48-5.20, P=0.001), exfoliation glaucoma (OR=1.70, 95% CI=1.18-2.43, P=0.004), and suspected glaucoma (OR=1.74, 95% CI=1.30-2.34, P<0.001), but not for normotensive glaucoma (OR=1.01, 95% CI=0.61-1.68, P=0.956).

CONCLUSIONS

Our study revealed an association between frailty and increased glaucoma risk and emphasized the significance of glaucoma screening in frail individuals. Targeted healthcare strategies can help prevent or delay irreversible blindness among middle-aged and older adults.

Prevalence and Risk Factors of Fundus Pathology in Patients with Type 2 Diabetes in a Northeastern Chinese Cohort

PURPOSE

To assess the prevalence of and risk factors for fundus pathology in patients with type 2 diabetes mellitus (T2DM) in a cohort from northeastern China.

METHODS

Patients were included from the Fushun Diabetic Retinopathy Cohort Study. Patients aged ≥ 30 years with T2DM were recruited between July 2012 and May 2013. Fundus pathology included retinal vascular occlusion (RVO), age-related macular degeneration (AMD), macular pathology, pathologic myopia (PM) and glaucomatous optic atrophy (GOA).

RESULTS

A Total of 1998 patients with gradable fundus photographs were included in this study, of whom 388 (19.42%) had fundus pathology regardless of whether they had diabetic retinopathy (DR). There were 187 (9.36%) patients with AMD, 97 (4.85%) with GOA, 67 (3.35%) with macular pathology, 35 (1.75%) with PM and 23 (1.15%) with RVO. Advanced age was significantly associated with AMD (odds ratio (OR), 95% confidence interval (CI): 1.03, 1.01-1.05), macular pathology (OR, 95% CI: 1.06, 1.03-1.09) and GOA (OR, 95% CI: 1.06, 1.04-1.09). A wider central retinal arteriolar equivalent was protective against PM (OR, 95% CI: 0.78, 0.66-0.92). Wider central retinal venular equivalent was a protective factor for PM (OR, 95% CI: 0.75, 0.68-0.82) and GOA (OR, 95% CI: 0.93, 0.87-0.99).

CONCLUSIONS

One-fifth of these patients in northeast China with T2DM had fundus pathology regardless of whether they had DR, indicating the importance of early screening and long-term follow-up.

Aging and "Age-Related" Diseases - What Is the Relation?

The study explores the intricate relationship between aging and the development of noncommunicable diseases [NCDs], focusing on whether these diseases are inevitable consequences of aging or primarily driven by lifestyle factors. By examining epidemiological data, particularly from hunter-gatherer societies, the study highlights that many NCDs prevalent in modern populations are rare in these societies, suggesting a significant influence of lifestyle choices. It delves into the mechanisms through which poor diet, smoking, and other lifestyle factors contribute to systemic physiological imbalances, characterized by oxidative stress, insulin resistance and hyperinsulinemia, and dysregulation of the sympathetic nervous system, the renin-angiotensin-aldosterone system, and the immune system. The interplay between this pattern and individual factors such as genetic susceptibility, biological variability, epigenetic changes and the microbiome is proposed to play a crucial role in the development of a range of age-related NCDs. Modified biomolecules such as oxysterols and advanced glycation end products also contribute to their development. Specific diseases such as benign prostatic hyperplasia, Parkinson's disease, glaucoma and osteoarthritis are analyzed to illustrate these mechanisms. The study concludes that while aging contributes to the risk of NCDs, lifestyle factors play a crucial role, offering potential avenues for prevention and intervention through healthier living practices. One possible approach could be to try to restore the physiological balance, e.g. through dietary measures [e.g. Mediterranean diet, Okinawan diet or Paleolithic diet] in conjunction with [a combination of] pharmacological interventions and other lifestyle changes.

[Primary open angle glaucoma and sleep apnea syndrome: A review of the literature]

The relationship between glaucoma and Obstructive Sleep Apnea Syndrome (OSAS) has long been discussed, with conflicting study findings. OSAS appears in the most recent studies to be more of an aggravating factor than an independent risk factor for glaucoma. Patients with OSAS may develop a more rapid progression of primary open-angle glaucoma (POAG). OSAS may damage the optic nerve not only by increasing the intraocular pressure (IOP) but also by altering the blood supply to the optic nerve as shown by more recent work with OCT-Angiography. Although the systemic benefits of Continuous Positive Airway Pressure (CPAP) have been demonstrated, few studies have evaluated its effect on the optic nerve. CPAP might act on glaucomatous neuropathy by improving the blood supply to the optic nerve. The study of this mechanism of action might provide new insights into the relationship between OSAS and glaucoma.

Factors Associated with Increased Intraocular Pressure in Type 2 Diabetes Patients

BACKGROUND

Over one-third of patients living with diabetes will develop ocular disease during their lifetime. The present study analyzes the association between metabolic and anthropometric markers, associated comorbidities, and intraocular pressure (IOP) in patients with type 2 diabetes mellitus (DM).

METHODS

The retrospective study included 87 adult patients with type 2 DM who underwent routine eye examinations and blood/urine tests.

RESULTS

67.9% of the patients had an IOP > 14.5 mmHg and only 41.3% had an HbA1c < 7%. In a multivariate regression analysis, the mean IOP was associated with diabetes duration in subjects with a disease duration < 15 years and an HbA1c < 7% (adjusted R2 = 0.29, p = 0.008). Also, patients with shorter diabetes duration and optimal glucose control had a lower mean IOP than patients with a higher HbA1c (mean IOP 15.1 mmHG vs. 18.9 mmHg, p = 0.04). The patient's age, anthropometric or metabolic markers, associated comorbidities like hypertension (HTN) or retinal angiosclerosis, and diabetes therapies were not associated with IOP in this study.

CONCLUSION

Diabetes progression is directly associated with increased IOP. Avoiding clinical inertia and optimizing glycemic control could prevent or delay the increase of IOP. Routine eye examination should include measuring IOP, not only diabetic retinopathy screening.

Prevalence of Ocular Hypertension and Other Risk Factors of Open-Angle Glaucoma Among Middle-Aged Adults in Al-Baha City, Saudi Arabia

Background Ocular hypertension (OHT), defined by elevated intraocular pressure (IOP) beyond standard levels, is a predominant risk factor for initiating and exacerbating glaucoma, a collection of progressive optic neuropathies responsible for irreversible vision loss. Given the profound implications for vision care, it is imperative to elucidate the interplay between OHT and glaucoma for effective clinical management. Objective The present study aims to measure IOP levels and identify risk factors associated with glaucoma among middle-aged individuals in Al-Baha City, Saudi Arabia. Methods A cross-sectional study was conducted over a six-month span (January-June 2022) in Al-Baha City. The study cohort comprised adults aged 35 and above attending a glaucoma awareness campaign at King Fahad Hospital, Al-Baha. Parameters such as demographics, socioeconomic status, medical and ocular history, and familial history of eye diseases were collated. Initial ophthalmologic assessments and IOP measurements were performed. Statistical analyses utilized Pearson's Chi-square test for nominal variables. Results The study encompassed 111 participants, 84 (75.7%) of whom were male, and 75 (67.6%) were of Saudi nationality. Notably, 102 (91.9%) reported no family history of glaucoma, 91 (81.1%) indicated no past medical history and 81 (73.0%) were not on any chronic medications. The mean IOP for participants' right and left eyes fluctuated between 18.2-21.5 mmHg and 18.9-22.1 mmHg, respectively. Factors such as age, gender, family history of glaucoma, past medical history, use of chronic medications, and history of ophthalmic surgeries demonstrated a statistically significant correlation with IOP (p<0.05). Conclusion This study highlights a higher prevalence of OHT in females, with several risk factors for OHT and glaucoma identified, such as familial history, vascular diseases, diabetes mellitus, and chronic medication use. Notably, our study did not observe a significant association with age or smoking. These findings emphasize the necessity of regular eye examinations and IOP monitoring, especially in high-risk groups.

Intraocular Pressure Variations in Postural Changes: Comparison between Obese and Non-Obese Controls

BACKGROUND

Comparing intraocular pressure (IOP) changes (ΔIOP) between obese subjects and non-obese controls in relation to different positions: standing, sitting, supine.

METHODS

the IOP was measured in both obese patients and non-obese controls groups with Tono-Pen AVIA in different positions following this sequence: after 5 min (5') in the standing position, sitting, supine, supine after 5 min (supine 5') and immediately after standing. ΔIOP values obtained comparing all positions were, therefore, evaluated.

RESULTS

92 eyes of 46 obese subjects aged between 18 and 59 years (mean 38.07 ± 11.51 years) and of a Body Mass Index (BMI) between 31.84 and 60.65 (mean 41.84 ± 7.05) were evaluated. A total of 48 eyes of 24 non-obese controls aged between 23 and 55 (mean 35.21 ± 11.96 years) and of a BMI between 18.20 and 26.79 (mean 21.04 ± 2.36) were also recruited. In obese subjects, there were statistically significant differences between the IOP in the supine position and the supine positions 5' with all other IOP measurements (p < 0.05). There were statistically significant differences between ΔIOP in both supine positions and prolonged standing positions obtained by obese subjects and non-obese controls (p < 0.05).

CONCLUSIONS

In obese subjects, there is a statistically significant increase in IOP in the supine positions that is significantly greater than the non-obese population. BMI is weakly correlated with IOP and ΔIOP in postural changes.

Evaluation of retinal nerve fibre layer thickness as a possible measure of diabetic retinal neurodegeneration in the EPIC-Norfolk Eye Study

BACKGROUND/AIMS

Markers to clinically evaluate structural changes from diabetic retinal neurodegeneration (DRN) have not yet been established. To study the potential role of peripapillary retinal nerve fibre layer (pRNFL) thickness as a marker for DRN, we evaluated the relationship between diabetes, as well as glycaemic control irrespective of diabetes status and pRNFL thickness.

METHODS

Leveraging data from a population-based cohort, we used general linear mixed models (GLMMs) with a random intercept for patient and eye to assess the association between pRNFL thickness (measured using GDx) and demographic, systemic and ocular parameters after adjusting for typical scan score. GLMMs were also used to determine: (1) the relationship between: (A) glycated haemoglobin (HbA1c) irrespective of diabetes diagnosis and pRNFL thickness, (B) diabetes and pRNFL thickness and (2) which quadrants of pRNFL may be affected in participants with diabetes and in relation to HbA1c.

RESULTS

7076 participants were included. After controlling for covariates, inferior pRNFL thickness was 0.94 µm lower (95% CI -1.28 µm to -0.60 µm), superior pRNFL thickness was 0.83 µm lower (95% CI -1.17 µm to -0.49 µm) and temporal pRNFL thickness was 1.33 µm higher (95% CI 0.99 µm to 1.67 µm) per unit increase in HbA1c. Nasal pRNFL thickness was not significantly associated with HbA1c (p=0.23). Similar trends were noted when diabetes was used as the predictor.

CONCLUSION

Superior and inferior pRNFL was significantly thinner among those with higher HbA1c levels and/or diabetes, representing areas of the pRNFL that may be most affected by diabetes.

Metabolic Health, Obesity, and Intraocular Pressure

Obesity has been associated with increased intraocular pressure (IOP), but the results are inconsistent. Recently, a subgroup of obese individuals with good metabolic profiles were suggested to have better clinical outcomes than normal-weight individuals with metabolic diseases. The relationships between IOP and different combinations of obesity and metabolic health status have not been investigated. Therefore, we investigated the IOP among groups with different combinations of obesity status and metabolic health status. We examined 20,385 adults aged 19 to 85 years at the Health Promotion Center of Seoul St. Mary's Hospital between May 2015 and April 2016. Individuals were categorized into four groups according to obesity (body mass index (BMI) ≥ 25 kg/m²) and metabolic health status (defined based on prior medical history or abdominal obesity, dyslipidemia, low high-density lipoprotein cholesterol, high blood pressure, or high fasting blood glucose levels upon medical examination). ANOVA and ANCOVA were performed to compare the IOP among the subgroups. The IOP of the metabolically unhealthy obese group (14.38 ± 0.06 mmHg) was the highest, followed by that of the metabolically unhealthy normal-weight group (MUNW, 14.22 ± 0.08 mmHg), then, the metabolically healthy groups (p < 0.001; 13.50 ± 0.05 mmHg and 13.06 ± 0.03 mmHg in the metabolically healthy obese (MHO) and metabolically healthy normal-weight groups, respectively). Subjects who were metabolically unhealthy showed higher IOP compared to their counterparts who were metabolically healthy at all BMI levels, and there was a linear increase in IOP as the number of metabolic disease components increased, but no difference between normal-weight vs. obese individuals. While obesity, metabolic health status, and each component of metabolic disease were associated with higher IOP, those who were MUNW showed higher IOP than those who were MHO, which indicates that metabolic status has a greater impact than obesity on IOP.

Genetic Factors Implicated in the Investigation of Possible Connections between Alzheimer's Disease and Primary Open Angle Glaucoma

Both Alzheimer's disease (AD) and primary open angle glaucoma (POAG) are diseases of primary global neurodegeneration with complex pathophysiologies. Throughout the published literature, researchers have highlighted similarities associated with various aspects of both diseases. In light of the increasing number of findings reporting resemblance between the two neurodegenerative processes, scientists have grown interested in possible underlying connections between AD and POAG. In the search for explanations to fundamental mechanisms, a multitude of genes have been studied in each condition, with overlap in the genes of interest between AD and POAG. Greater understanding of genetic factors can drive the research process of identifying relationships and elucidating common pathways of disease. These connections can then be utilized to advance research as well as to generate new clinical applications. Notably, AD and glaucoma are currently diseases with irreversible consequences that often lack effective therapies. An established genetic connection between AD and POAG would serve as the basis for development of gene or pathway targeted strategies relevant to both diseases. Such a clinical application could be of immense benefit to researchers, clinicians, and patients alike. This paper aims to summarize the genetic associations between AD and POAG, describe common underlying mechanisms, discuss potential areas of application, and organize the findings in a review.

The effect of body mass index reduction on intraocular pressure in a large prospective cohort of apparently healthy individuals in Israel

PURPOSE

To investigate the effect of change in body mass index (BMI) on intraocular pressure (IOP) in a large cohort of apparently healthy volunteers who underwent an annual comprehensive screening examinations.

METHODS

This study included individuals who were enrolled in the Tel Aviv Medical Center Inflammation Survey (TAMCIS) and had IOP and BMI measurements at their baseline and follow up visits. Relationships between BMI and IOP and the effect of change in BMI on IOP were investigated.

RESULTS

A total of 7,782 individuals had at least one IOP measurement at their baseline visit, and 2,985 individuals had ≥2 visits recorded. The mean (SD) IOP (right eye) was 14.6 (2.5) mm Hg and mean (SD) BMI was 26.4 (4.1) kg/m2. IOP positively correlated with BMI levels (r = 0.16, p<0.0001). For individuals with morbid obesity (BMI≥35 kg/m2) and ≥2 visits, a change in BMI between the baseline and first follow-up visits correlated positively with a change in the IOP (r = 0.23, p = 0.029). Subgroup analysis of subjects who had a reduction of at least 2 BMI units showed a stronger positive correlation between change in BMI and change in IOP (r = 0.29, p<0.0001). For this subgroup, a reduction of 2.86 kg/m2 of BMI was associated with a reduction of 1 mm Hg in IOP.

CONCLUSIONS

BMI loss correlated with reduction in IOP, and this correlation was more pronounced among morbidly obese individuals.

Fatty Liver Is an Independent Risk Factor for Elevated Intraocular Pressure

Elevated intraocular pressure (EIOP) is a major risk factor for glaucoma. Both EIOP and fatty liver share metabolic risk factors, which implies a possible link between EIOP and fatty liver. We aimed to determine the association of fatty liver with EIOP and estimate the effect of fatty liver on EIOP directly and indirectly through insulin resistance. Data from 16,240 adults who underwent health examinations at a single center were analyzed. Multiple logistic regression analyses revealed that fully adjusted odds ratio (OR) and 95% confidence interval (CI) for EIOP in the fatty liver group compared to the non-fatty liver group were 1.36 and 1.08-1.71. Alcoholic liver disease was associated with EIOP in subgroup analysis (OR = 1.80, 95% CI: 1.27-2.56). There was a linear dose-response relationship between EIOP and the severity of fatty liver. Mediation analysis revealed that the total effect of fatty liver on intraocular pressure was 0.90 (0.81-0.99), with a direct effect of 0.81 (0.71-0.90) and an indirect effect of 0.09 (0.06-0.11) through insulin resistance. Fatty liver is independently associated with EIOP. It primarily has a direct effect on intraocular pressure. This suggests that evaluation of EIOP should be considered in patients with fatty liver.

Ocular manifestations of central insulin resistance

Central insulin resistance, the diminished cellular sensitivity to insulin in the brain, has been implicated in diabetes mellitus, Alzheimer's disease and other neurological disorders. However, whether and how central insulin resistance plays a role in the eye remains unclear. Here, we performed intracerebroventricular injection of S961, a potent and specific blocker of insulin receptor in adult Wistar rats to test if central insulin resistance leads to pathological changes in ocular structures. 80 mg of S961 was stereotaxically injected into the lateral ventricle of the experimental group twice at 7 days apart, whereas buffer solution was injected to the sham control group. Blood samples, intraocular pressure, trabecular meshwork morphology, ciliary body markers, retinal and optic nerve integrity, and whole genome expression patterns were then evaluated. While neither blood glucose nor serum insulin level was significantly altered in the experimental or control group, we found that injection of S961 but not buffer solution significantly increased intraocular pressure at 14 and 24 days after first injection, along with reduced porosity and aquaporin 4 expression in the trabecular meshwork, and increased tumor necrosis factor α and aquaporin 4 expression in the ciliary body. In the retina, cell density and insulin receptor expression decreased in the retinal ganglion cell layer upon S961 injection. Fundus photography revealed peripapillary atrophy with vascular dysregulation in the experimental group. These retinal changes were accompanied by upregulation of pro-inflammatory and pro-apoptotic genes, downregulation of anti-inflammatory, anti-apoptotic, and neurotrophic genes, as well as dysregulation of genes involved in insulin signaling. Optic nerve histology indicated microglial activation and changes in the expression of glial fibrillary acidic protein, tumor necrosis factor α, and aquaporin 4. Molecular pathway architecture of the retina revealed the three most significant pathways involved being inflammation/cell stress, insulin signaling, and extracellular matrix regulation relevant to neurodegeneration. There was also a multimodal crosstalk between insulin signaling derangement and inflammation-related genes. Taken together, our results indicate that blocking insulin receptor signaling in the central nervous system can lead to trabecular meshwork and ciliary body dysfunction, intraocular pressure elevation, as well as inflammation, glial activation, and apoptosis in the retina and optic nerve. Given that central insulin resistance may lead to neurodegenerative phenotype in the visual system, targeting insulin signaling may hold promise for vision disorders involving the retina and optic nerve.

Body shape and risk of glaucoma: A Mendelian randomization

Background

Body size (BS) is one of the risk factors for the development of many clinical diseases, but the relationship between BS and glaucoma is controversial. Herein, we try to use Mendelian randomization (MR) method to study BS causal association with glaucoma risk from the genetic level.

Methods

The Body Size was determined through anthropometric traits (ATs), such as body mass index (BMI), waist-to-hip ratio adjusted by body mass index (WHRadjBMI), waist-to-hip ratio (WHR), and waist circumference (WC). Association of single nucleotide polymorphisms (SNPs) with each AT and glaucoma were determined individually from the aggregated data of the Genetic Investigation of Anthropometric Traits (GIANT) consortium and the FinnGen study summary data (8,591 cases with glaucoma and 210,201 controls). To explore the role of BS and glaucoma, a two-sample MR analysis was performed on genome-wide association study (GWAS) data. Besides, three MR methods [inverse variance weighted (IVW), Weighted median, and MR-Egger regression] were used to get the whole causal estimate for multiple instrumental SNPs.

Results

BMI (OR = 1.20; 95% CI = 1.02-1.41; P = 0.03) and WC (OR = 1.32; 95% CI =1.04-1.69; P = 0.03) were associated with a risk of glaucoma. Besides, genetically predicted WHRadjBMI (OR = 1.10; 95% CI = 0.88-1.35; P = 0.43) and WHR (OR = 1.22; 95% CI = 0.93-1,572; P = 0.14) were not associated with glaucoma. No heterogeneity and directional pleiotropy were detected.

Conclusion

The data of this study revealed that increased BMI and WC are potential risk factors for glaucoma, and WHRadjBMI and WHR are not associated with the occurrence of glaucoma.

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

PRCIS

For patients with glaucoma, metabolic syndrome was associated with higher intraocular pressure and greater central corneal thickness. Patients with metabolic syndrome were more likely to have ocular hypertension.

PURPOSE

The purpose of this study was to determine whether glaucomatous optic neuropathy, also known as glaucoma, and ocular hypertension are more likely to occur in patients with metabolic syndrome.

PATIENTS AND METHODS

Patients in Olmsted County, MN, were identified as having metabolic syndrome based on diagnosis codes, laboratory values, and/or medication use to meet 3 or more of the 5 standard criteria for diagnosing metabolic syndrome: systemic hypertension, hyperglycemia, hypertriglyceridemia, reduced high-density lipoprotein cholesterol, and central adiposity defined by increased body mass index. Patients with glaucoma, including primary open angle, low tension, pigment dispersion, and pseudoexfoliation, were identified using diagnostic codes. The charts of patients with glaucoma were individually reviewed to collect visual acuity, intraocular pressure, cup to disc ratio, central corneal thickness, visual field mean deviation, retinal nerve fiber layer thickness, and treatment of intraocular pressure. Patients with ocular hypertension were separately identified and similarly evaluated.

RESULTS

For patients with glaucoma, those with metabolic syndrome had higher intraocular pressure and greater central corneal thickness compared with those without metabolic syndrome. After adjustment for central corneal thickness, there was no longer a significant difference in intraocular pressure between groups. Metabolic syndrome was also associated with the diagnosis of ocular hypertension, and although central corneal thickness trended higher in patients with metabolic syndrome, it did not attain statistical significance.

CONCLUSION

In Olmsted County, though metabolic syndrome was associated with ocular hypertension and higher intraocular pressure in patients with glaucoma, the results were likely related to a thicker central corneal in this patient population.

The Causal Association Between Obesity and Primary Open-Angle Glaucoma: A Two-Sample Mendelian Randomization Study

The correlation between obesity and primary open-angle glaucoma (POAG) has not yet been fully established. The aim of this study was to investigate the causal relationship between obesity and POAG by a two-sample Mendelian randomization (MR) study. In this study, body mass index (BMI), an index to evaluate general obesity, and waist and hip circumference, indices to evaluate abdominal obesity, were selected as exposures in MR analysis. Single-nucleotide polymorphisms (SNPs) were chosen as instrumental variables (IVs). Summary data from genome-wide association studies (GWASs) based on a European ancestry by Locke et al., with regard to BMI, and Shungin et al., with regard to waist and hip circumference, were used. Genetic predictors of POAG were obtained from public GWAS summary data. To assess the causal effect of obesity on POAG, the inverse variance-weighted (IVW) method was used as the primary method, and other methods, such as MR-Egger, weighted median, simple mode, and weighted mode, were also used as complementary analyses. Finally, we performed Cochran's Q statistic to assess heterogeneity, and sensitivity analysis was performed to evaluate the reliability and stability of the MR results. MR analysis showed that BMI has a positive effect on the risk of POAG, with 1 standard deviation (SD) increase in BMI; the risk of POAG increases by approximately 90.9% [OR = 1.909; 95% CI= (1.225, 2.975); p = 0.0042)] (analyzed by IVW); there were no heterogeneity and pleiotropy in the result; and waist circumference also had a positive effect on the risk of POAG [OR = 2.319; 95% CI= (1.071, 5.018); p = 0.033)] analyzed by weighted median. As hip circumference increases, with 1 SD increase in hip circumference, the risk of POAG increases by approximately 119% [OR = 2.199; 95% CI= (1.306, 3.703); p = 0.00305)] estimated by IVW, there were not heterogeneity and pleiotropy as for the result. Our study for the first time confirms that obesity might increase the risk of POAG using two-sample MR analysis. These results might provide guidance on the prevention and treatment of POAG.

The Correlation Between Body Weight and Intraocular Pressure

INTRODUCTION: Preflight body weight is a strong predictor of visual changes in spaceflight. To understand the effect of body weight on the eye, we examined the effect of increased body mass index on intraocular pressure on Earth.METHODS: We conducted a systematic review to summarize the relationship between weight parameters (including body mass index (BMI) and obesity indices), and intraocular pressure (IOP). Study selection and data extraction were performed in duplicate using EMBASE, MEDLINE, and CENTRAL, from database inception to the second week of April 2020.RESULTS: A total of 66 individual studies were included for qualitative analysis from the 1364 studies eligible for title and abstract screening. A total of 39 studies were available for quantitative analysis. The average BMI was 25.9 (range, 20.148.8) and the average IOP was 14.9 mmHg (range, 11.627.8). The overall pooled RR between BMI and elevated intraocular pressure (IOP) was 1.06 (95 CI%, 1.041.07), meaning for each unit increase in BMI one is 6 more likely of having higher IOP than baseline. Two studies assessed the effects of bariatric surgery, and both showed significant decreases in IOP postoperatively.CONCLUSION: A higher BMI was associated with increased IOP in ground-based studies. IOP also decreased with weight loss. These data support the idea that alterations in body weight affect intraocular pressures. Further research is needed to understand the relationship between body weight, IOP, and microgravity-induced visual changes. This finding may also be useful clinically.Khan S, Kirubarajan A, Lee M, Pitha I, Buckey JC Jr. The correlation between body weight and intraocular pressure. Aerosp Med Hum Perform. 2021; 92(11):886-897.

Association between diabetes status and subsequent onset of glaucoma in postmenopausal women

The purpose of this study was to analyze the risk of glaucoma based on diabetes status using a large nationwide longitudinal cohort of postmenopausal women. This study included 1,372,240 postmenopausal women aged ≥ 40 years who underwent National Health Screening Program in 2009. Subjects were classified into the following 5 categories based on diabetes status: no diabetes, impaired fasting glucose (IFG), new onset diabetes, diabetes treated with oral hypoglycemic medication, and diabetes treated with insulin. Subjects were followed from 2005 through 2018, and hazard ratios of glaucoma onset were calculated for each group. Subgroup analyses of subjects stratified by age, smoking, drinking, hypertension, and dyslipidemia were performed. During the follow up period, 42,058 subjects developed glaucoma. The adjusted hazard ratio was 1.061 (95% CI, 1.036–1.086) in the IFG group, 1.151 (95% CI, 1.086–1.220) in the new onset diabetes group, 1.449 (95% CI, 1.406–1.493) in the diabetes treated with oral hypoglycemic medication group, and 1.884(95% CI, 1.777–1.999) in the diabetes treated with insulin group compared to the no diabetes group. The results were consistent in subgroup analyses after stratifying by age, lifestyle factors (smoking and drinking), and comorbidities (hypertension and dyslipidemia). Diabetes status is associated with increased risk of glaucoma development in postmenopausal women.

Association Between Diabetes, Diabetic Retinopathy, and Glaucoma

PURPOSE OF REVIEW

The strength of the relationship between diabetes, diabetic retinopathy (DR), and glaucoma remains controversial. We review evidence supporting and refuting this association and explore mechanistic pathological and treatment relationships linking these diseases.

RECENT FINDINGS

While studies have shown diabetes/DR may increase the risk for glaucoma, this remains inconsistently demonstrated. Diabetes/DR may contribute toward glaucomatous optic neuropathy indirectly (either by increasing intraocular pressure or vasculopathy) or through direct damage to the optic nerve. However, certain elements of diabetes may slow glaucoma progression, and diabetic treatment may concurrently be beneficial in glaucoma management. Diabetes plays a significant role in poor outcomes after glaucoma surgery. While the relationship between diabetes/DR and glaucoma remains controversial, multiple mechanistic links connecting pathophysiology and management of diabetes, DR, and glaucoma have been made. However, a deeper understanding of the causes of disease association is needed.

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.

Metabolic syndrome and the aging retina

PURPOSE OF REVIEW

This review explores metabolic syndrome (MetS) as a risk factor that accelerates aging in retinal neurons and may contribute to the neurodegeneration seen in glaucomatous optic neuropathy (GON) and age-related macular degeneration (AMD).

RECENT FINDINGS

Both animal model experiments and epidemiologic studies suggest that metabolic stress may lead to aberrant regulation of a number of cellular pathways that ultimately lead to premature aging of the cell, including those of a neuronal lineage.

SUMMARY

GON and AMD are each leading causes of irreversible blindness worldwide. Aging is a significant risk factor in the specific retinal neuron loss that is seen with each condition. Though aging at a cellular level is difficult to define, there are many mechanistic modifiers of aging. Metabolic-related stresses induce inflammation, oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, alterations to the unfolded protein response, defects in autophagy, alterations to the microbiome, and deposition of advanced glycation end products that can all hasten the aging process. Due to the number of variables related to metabolic health, defining criteria to enable the study of risk factors at a population level is challenging. MetS is a definable constellation of related metabolic risk factors that includes enlarged waist circumference, dyslipidemia, systemic hypertension, and hyperglycemia. MetS has been associated with both GON and AMD and may contribute to disease onset and/or progression in each disease.

Carbohydrate intake and risk of glaucoma in the sun cohort

PURPOSE

To assess the association between carbohydrates (CH) intake and glaucoma incidence.

METHODS

18,247 volunteer participants (183,067 person-years at risk) with 10-year of median follow-up were included in this prospective dynamic cohort. Baseline total CH intake (g/d) was categorised in quartiles and classified in nine different CH food sources. Self-reported diagnosis of glaucoma was collected at baseline and on biennial follow-up questionnaires. CH intake and glaucoma diagnosis were validated in a subsample of participants. We studied potential confounders and effect modificators, including diabetes. The relationship between CH intake and glaucoma incidence was analysed using multivariable Cox proportional hazards ratio (HR) models to adjust for potential confounding factors.

RESULTS

During 10 years of median follow-up, a total of 242 new cases of glaucoma were identified. Participants in the highest quartile of baseline CH intake had a significantly higher risk of glaucoma as compared to participants in the lowest quartile [HR 1.50 (95% Confidence interval (CI): 1.01-2.25), p for trend = 0.042]. None of the nine CH food groups was individually related to glaucoma. In stratified analyses, after excluding all cases of diabetes, the HR comparing extreme quartiles of CH intake was 1.77 (95% CI: 1.15-2.74).

CONCLUSIONS

Our results suggest that a higher intake of total carbohydrates is associated with a higher risk of incident glaucoma. The total amount of CH, rather than the specific food sources of CH, seems to play a major role, and this association does not seem to be confounded or modified by diabetic status.

Serum Calcium Level as a Useful Surrogate for Risk of Elevated Intraocular Pressure

BACKGROUND

Uncontrolled intraocular pressure (IOP) plays a principal role in the deterioration of glaucoma, and the intraocular pressure is also accepted as the most important modifiable factor. Calcium ion has been found to play a vital role in regulating the resistance of the trabecular meshwork in humans. However, the relationship between serum total calcium and IOP has not been well-established.

METHODS

We investigated the association between serum total calcium and the IOP in a large population (14,037 eligible participants, consisting of 7712 men and 6325 women, were included) at the Tri-Service General Hospital from 2010 to 2016. Several models of covariate adjustments associated with IOP were designed. Univariate and multivariate regression analysis was performed for gender differences in the association between the serum total calcium level and IOP.

RESULTS

There was a significant relationship between serum total calcium levels and IOP in women and men with a β coefficient of 0.050 (95% confidence interval (CI), 0.030-0.069) and 0.025 (95%CI, 0.007-0.043). Notably, participants in the highest tertiles of serum total calcium levels had significantly higher IOP, in both the male and female participants.

CONCLUSIONS

Our study shows that IOP is significantly associated with serum total calcium levels in a large Asian population. This study supports the notion that serum total calcium may play an important role in groups at high risk for elevated IOP.

Citicoline Modulates Glaucomatous Neurodegeneration Through Intraocular Pressure-Independent Control

Glaucoma is a neurodegenerative disease that causes progressive, irreversible vision loss. Currently, intraocular pressure (IOP) is the only modifiable risk factor for glaucoma. However, glaucomatous degeneration may continue despite adequate IOP control. Therefore, there exists a need for treatment that protects the visual system, independent of IOP. This study sought, first, to longitudinally examine the neurobehavioral effects of different magnitudes and durations of IOP elevation using multi-parametric magnetic resonance imaging (MRI), optokinetics and histology; and, second, to evaluate the effects of oral citicoline treatment as a neurotherapeutic in experimental glaucoma. Eighty-two adult Long Evans rats were divided into six groups: acute (mild or severe) IOP elevation, chronic (citicoline-treated or untreated) IOP elevation, and sham (acute or chronic) controls. We found that increasing magnitudes and durations of IOP elevation differentially altered structural and functional brain connectivity and visuomotor behavior, as indicated by decreases in fractional anisotropy in diffusion tensor MRI, magnetization transfer ratios in magnetization transfer MRI, T1-weighted MRI enhancement of anterograde manganese transport, resting-state functional connectivity, visual acuity, and neurofilament and myelin staining along the visual pathway. Furthermore, 3 weeks of oral citicoline treatment in the setting of chronic IOP elevation significantly reduced visual brain integrity loss and visual acuity decline without altering IOP. Such effects sustained after treatment was discontinued for another 3 weeks. These results not only illuminate the close interplay between eye, brain, and behavior in glaucomatous neurodegeneration, but also support a role for citicoline in protecting neural tissues and visual function in glaucoma beyond IOP control.

Relationship of Obesity and Related Disorders with Ocular Parameters in Children and Adolescent

PURPOSE

To evaluate the effect of obesity and obesity-related high blood pressure (BP) on the retinal nerve fiber layer (RNFL) and macula in children and adolescents.

MATERIALS AND METHODS

Thirty-two obese patients followed up in the pediatrics endocrinology clinic between 2018 and 2019 were evaluated in the ophthalmology clinic. The results were compared with 25 healthy subjects, matched for age and sex. Anthropometric measurements, and systolic and diastolic BP were measured. The study consisted of three groups: Group 1, patients with obesity; Group 2, those with obesity and associated hypertension (obesity-related HT); and Group 3, healthy controls. A complete ophthalmologic examination was performed. Macular and RNFL thicknesses were determined using spectral domain optical coherence tomography (SD-OCT).

RESULTS

There were no statistically significant differences between the groups in terms of gender, age, and intraocular pressure (p > .05). The inferior RNFL thickness and central foveal thickness were statistically thinner in the obesity-related HT group (p < .001 and p = .040). The systolic and diastolic BP and fasting glucose values were significantly higher in the obesity-related HT group than the other groups (p < .001; p < .001; p = .026, respectively). In linear regression modeling in obese and obesity-related HT groups, a significant assocation was found between diastolic BP and temporal RNFL thickness (p = .027) as well as between the systolic BP and triglyceride values and the nasal RNFL thickness values (p = .016 and p = .025, respectively).

CONCLUSIONS

Inferior RNFL thickness and central foveal thickness were significantly thinner in patients with obesity-related HT. The effects of obesity-related HT on the retina should be evaluated using SD OCT, since no signs were found in a routine ocular examination.

Predicting intraocular pressure using systemic variables or fundus photography with deep learning in a health examination cohort

The purpose of the current study was to predict intraocular pressure (IOP) using color fundus photography with a deep learning (DL) model, or, systemic variables with a multivariate linear regression model (MLM), along with least absolute shrinkage and selection operator regression (LASSO), support vector machine (SVM), and Random Forest: (RF). Training dataset included 3883 examinations from 3883 eyes of 1945 subjects and testing dataset 289 examinations from 289 eyes from 146 subjects. With the training dataset, MLM was constructed to predict IOP using 35 systemic variables and 25 blood measurements. A DL model was developed to predict IOP from color fundus photographs. The prediction accuracy of each model was evaluated through the absolute error and the marginal R-squared (mR2), using the testing dataset. The mean absolute error with MLM was 2.29 mmHg, which was significantly smaller than that with DL (2.70 dB). The mR2 with MLM was 0.15, whereas that with DL was 0.0066. The mean absolute error (between 2.24 and 2.30 mmHg) and mR2 (between 0.11 and 0.15) with LASSO, SVM and RF were similar to or poorer than MLM. A DL model to predict IOP using color fundus photography proved far less accurate than MLM using systemic variables.

Metabolic Syndrome Is Associated With Ocular Hypertension and Glaucoma

Glaucoma remains the world's leading cause of irreversible blindness and though intraocular pressure (IOP) is the most prevalent risk factor and only reliable therapeutic target, a number of systemic disease associations have been reported. Metabolic syndrome (MetS) is a constellation of findings that includes systemic hypertension, abdominal obesity, glucose intolerance, and dyslipidemia. MetS is becoming increasingly common worldwide, with prevalence up to 40% in some countries. Not only is MetS a significant cause of morbidity, but it is also associated with an increase in all-cause mortality. Reports have been conflicting regarding the association of individual components of MetS, including systemic hypertension and diabetes, with elevated IOP or glaucoma. However, though limitations in the existing literature are present, current evidence suggests that MetS is associated with IOP as well as glaucoma. Additional studies are needed to clarify this association by incorporating additional metrics including assessment of central corneal thickness as well as optic nerve structure and function. Future studies are also needed to determine whether lifestyle modification or systemic treatment of MetS could reduce the incidence or progression of glaucoma.

Ocular findings in metabolic syndrome: a review

Metabolic syndrome (MetS) has emerged as a worldwide health hazard of the modern lifestyle, representing a cluster of metabolic abnormalities and a risk factor for cardiovascular disease. Eye diseases, such as diabetic retinopathy, central retinal artery occlusion, cataract, age-related macular degeneration, glaucoma, and dry eye syndrome have been linked with many of MetS components. Their relationship with MetS itself is, however, a recent topic of investigation. This review aims to gather published evidence supporting associations between ocular findings and MetS and to explore the related physiopathological processes that congregate in this syndrome and lead to these diseases. Despite compiling interesting and compelling evidence, it raises awareness to the need of further studies in this field to keep solidifying these associations and unveiling the pathological processes that support them. It ultimately targets MetS patients as a population of individuals who are at increased risk of developing age-related eye diseases and vision loss.

A Cohort Study on Associations between Fundus/intraocular Pressure Abnormality and Medical Check-up Items

PURPOSE

To evaluate the associations between medical check-up items (MCI) for fundus and intraocular pressure abnormality (FIPA) diseases in the Department of Health Management Centre, the Fifth Affiliated Hospital of Sun Yat-sen University (DHMC-FHS).

PATIENTS AND METHODS

Individuals who visited DHMC-FHS and underwent MCI between June 2017 to May 2019 were included, 3237 subjects. A total of 356 participants were diagnosed as FIPA and enrolled. The general clinical characteristics were collected. Diseases for FIPA diagnosed included five cohort, high intraocular pressure, diabetic retinopathy, hypertension fundus arteriosclerosis, large eye cup, and high myopia fundus changes. Possible impact factors of MCI included blood routine, B-ultrasound, heart rate, hypertension, hyperlipidemia, standard vision, cerebral arteriosclerosis, body mass, arterial/carotid arteriosclerosis, etc. Further, the Pearson's correlation coefficients and logistic regression analyses were used to examine associations between MCI and FIPA.

RESULTS

The weighted study population who belonged to FIPA included 356 subjects. There were significant differences in age, IOP, habitual exercise, smoking, sleep duration (P˂0.05) between FIPA and without FIPA. And RBC, Hemoglobin, B-ultrasound abnormal event, heart rate, systolic pressure, diastolic pressure, TC, LDL-C, standard vision, cerebral arteriosclerosis, body mass index, carotid arteriosclerosis were positively correlated with high intraocular pressure, hypertension fundus arteriosclerosis and high myopia fundus changes (P < .05). Possible prognosis risk factors, higher IOP, habitual exercise and more frequent smoking affect FIPA prognosis significantly [Odds ratio (OR) = 0.53, P = .01; OR = 0.13, P = .03; OR = 0.83; P = .04, respectively].

CONCLUSION

Of FIPA participants, high intraocular pressure, hypertension fundus arteriosclerosis and high myopia fundus changes were shown a positive relationship with MCI. Control IOP, habitual exercise and less frequent smoking were regarded as positive associations with decreased FIPA. These findings could help us prevent and diagnose FIPA diseases in time via MCI.

Effect of Diabetes Control on Rates of Structural and Functional Loss in Patients with Glaucoma

PURPOSE

To investigate the association between levels of diabetes mellitus (DM) control and rates of visual field and retinal nerve fiber layer (RNFL) loss over time in glaucoma.

DESIGN

Retrospective cohort study.

PARTICIPANTS

A total of 351 eyes of 222 patients with type 2 DM with concomitant primary open-angle glaucoma (POAG) or suspected glaucoma extracted from the Duke Glaucoma Registry.

METHODS

All patients had at least 2 reliable standard automated perimetry (SAP) tests, 2 spectral domain OCT (SD-OCT) tests, and 2 glycated hemoglobin (HbA1c) measures over time with a minimum follow-up of 6 months. Values of HbA1c were summarized for each patient as mean, peak, and fluctuation across time. Multivariable linear mixed models were used to estimate the effect of HbA1c on rates of change in SAP mean deviation (MD) and OCT RNFL thickness loss over time while adjusting for various confounding factors.

MAIN OUTCOME MEASURES

Rates of change in MD and RNFL thickness over time.

RESULTS

Subjects had a mean baseline age of 62.5 ± 10.2 years and follow-up time of 6.9 ± 5.1 years. Subjects had an average of 4.8 SAP tests (range, 2-28), 3.6 SD-OCT tests (range, 2-10), and 8.3 HbA1c tests (range, 2-21). Average HbA1c mean was 7.1% ± 1.1% (range, 5.4-11.7), peak HbA1c over time was 8.1% ± 2% (range, 5.5-15.6), and HbA1c fluctuation was 0.6% ± 0.6% (range, 0-4.4). Mean rate of SAP MD change was -0.09 ± 0.20 decibel/year (median -0.06 decibel/year; interquartile range -0.15 to 0.01 decibel/year), and mean rate of RNFL change was -0.83 ± 0.51 μm/year (median -0.76 μm/year; interquartile range -1.06 to 0.56 μm/year). After adjustment for confounding factors, mean, peak, and fluctuation in HbA1c levels were not significantly associated with rates of MD change over time (P = 0.994, P = 0.689, P = 0.920, respectively), nor were rates of change in RNFL loss over time (P = 0.805, P = 0.575, P = 0.770).

CONCLUSIONS

We did not find a significant association between diabetes control, as measured by levels of HbA1c, and rates of visual field or RNFL loss over time in individuals with glaucoma or suspected glaucoma.

Association between metabolic risk factors and optic disc cupping identified by deep learning method

PURPOSE

This study aims to investigate correlation between metabolic risk factors and optic disc cupping and the development of glaucoma.

METHODS

This study is a retrospective, cross-sectional study with over 20-year-old patients that underwent health screening examinations. Intraocular pressure (IOP), fundus photographs, Body Mass Index (BMI), waist circumference (WC), serum triglycerides, serum HDL cholesterol (HDL-C), serum LDL cholesterol (LDL-C), systolic blood pressure (BP), diastolic BP, and serum HbA1c were obtained to analyse correlation between metabolic risk factors and glaucoma. Eye with glaucomatous optic neuropathy(GON) was defined as having an optic disc with either vertical cup-to-disc ratio(VCDR) ≥ 0.7 or a VCDR difference ≥ 0.2 between the right and left eyes by measuring VCDR with deep learning approach.

RESULTS

The study comprised 15,585 subjects and 877 subjects were diagnosed as GON. In univariate analyses, age, BMI, systolic BP, diastolic BP, WC, triglyceride, LDL-C, HbA1c, and IOP were significantly and positively correlated with VCDR in the optic nerve head. In linear regression analysis as independent variables, stepwise multiple regression analyses revealed that age, BMI, systolic BP, HbA1c, and IOP showed positive correlation with VCDR. In multivariate logistic analyses of risk factors and GON, higher age (odds ratio [OR], 1.054; 95% confidence interval [CI], 1.046-1.063), male gender (OR, 0.730; 95% CI, 0.609-0.876), more obese (OR, 1.267; 95% CI, 1.065-1.507), and diabetes (OR, 1.575; 95% CI, 1.214-2.043) remained statistically significant correlation with GON.

CONCLUSIONS

Among the metabolic risk factors, obesity and diabetes as well as older age and male gender are risk factors of developing GON. The glaucoma screening examinations should be considered in the populations with these indicated risk factors.

Gender-Specific Association Between Serum Uric Acid and Incident High Intraocular Pressure in Chinese Population: A Cross-Sectional Study

Purpose

The purpose of this study was to investigate the relationship between high intraocular pressure (IOP) and uric acid.

Methods

In a retrospective cross-sectional study, 19,147 participants were included in 2018. Serum uric acid (SUA) was cut to four groups as Q1 to Q4, according to the quartiles. The odds ratio (OR) and 95% confidence interval (CI) of different SUA levels were estimated by a binomial logistic regression model in men and women. A restrictive cubic spline method was used to estimate the dose-response relationship between uric acid and high IOP. Subgroup analysis was performed to find the gender-specific association between uric acid and high IOP.

Results

In women, after adjusting for confounding factors, the Q3 and Q4 of SUA levels were significantly associated with the risk of high IOP. The OR with 95% CI for Q3 and Q4 were 1.77 (1.22, 2.57) and 1.51 (1.01, 2.26), respectively, Q1 as a reference. For men, SUA levels were not associated with the incidence of high IOP. Moreover, the spline analysis found an inverted U‐shaped relationship between uric acid and high IOP in women (P = 0.0171).

Conclusions

Elevated levels of SUAwere independently associated with an increased risk of high IOP in women, but not in men. In addition, uric acid had an inverse U-shaped nonlinear dose-response relationship with high IOP in women.

Systemic factors associated with intraocular pressure among subjects in a health examination program in Japan

Background

To elucidate the possible effect of various systemic factors on intraocular pressure (IOP) using a dataset from a health examination program database in Japan.

Methods

This cross-sectional study included 1569 subjects selected from the 2287 subjects who comprised the database. Various systemic parameters including age, sex, height, body weight, waist circumference, percent body fat, blood pressure (BP), pulse rate, body mass index, 28 blood examination values, intimal medial thicknesses of both carotid arteries, and intraocular pressure (IOP) values measured by non-contact tonometry in both eyes were collected. The possible correlation between the IOP and other parameters was assessed initially by univariate analyses followed by multivariate analyses.

Results

Stepwise multivariate analyses, which included all parameters extracted by the univariate analyses (p<0.1) and sex, identified the same six parameters as indicators of the IOP values for each right and left IOP model. Among the parameters, age (r = -0.05 and -0.04/year for right and left IOPs, respectively) was associated negatively and the percent body fat (r = 0.06 and 0.05/%), systolic BP (r = 0.02 and 0.03/mmHg), pulse rate (r = 0.03 and 0.03/counts/minutes), albumin (r = 1.12 and 1.00/g/dL), and hemoglobin A1c (r = 0.38 and 0.44/%) were associated positively with the IOP in each eye.

Conclusions

Older age was associated with low IOP, while factors reflecting the metabolic syndrome were associated with high IOP in our study population.

Metabolic Health, Obesity, and the Risk of Developing Open-Angle Glaucoma: Metabolically Healthy Obese Patients versus Metabolically Unhealthy but Normal Weight Patients

BACKGROUND

This study sought to investigate the associations between metabolic health status, obesity, and incidence of primary open-angle glaucoma (POAG).

METHODS

In this nationwide, population-based, longitudinal prospective cohort study conducted using the Korean National Health Insurance System, we categorized all subjects based on presence and severity of metabolic syndrome and obesity. Insurance claims data were used to identify POAG development. Then, Cox regression was applied to calculate the hazard of developing POAG in people with various components of metabolic syndrome, obesity, or their combination.

RESULTS

Of the total 287,553 subjects, 4,970 (1.3%) developed POAG. High fasting glucose, blood pressure, and total cholesterol levels were all associated with increased risk of developing POAG. Regarding obesity level, people with body mass index (BMI) greater than 30 kg/m² were more likely to develop POAG than those with normal BMI. Also, people with greater number of metabolic syndrome components showed a greater POAG incidence. People who are metabolically unhealthy and obese (adjusted hazard ratio [HR], 1.574; 95% confidence interval [CI], 1.449 to 1.711) and those who are metabolically unhealthy nonobese (MUNO: adjusted HR, 1.521; 95% CI, 1.405 to 1.645) but not those who are metabolically healthy obese (MHO: adjusted HR, 1.019; 95% CI, 0.907 to 1.144) had an increased hazard of developing POAG compared with metabolically healthy nonobese (MHNO) subjects.

CONCLUSION

Metabolic health status and obesity were significantly associated with increased risk of POAG incidence. MUNO subjects but not MHO subjects showed a higher risk of POAG development than did MHNO subjects, suggesting that metabolic status is more important than obesity in POAG.

Relationships of diabetes and hyperglycaemia with intraocular pressure in a Japanese population: the JPHC-NEXT Eye Study

Although a meta-analysis previously suggested a positive relationship between diabetes and intraocular pressure (IOP), the interrelationships among diabetes, IOP, and other ocular biometric parameters remain unclear. The present study investigated the relationships of diabetes, haemoglobin A1c (HbA1c), and serum glucose with IOP and ocular hypertension (IOP > 21 mmHg) in non-glaucomatous Japanese adults living in Chikusei City. Diabetes was defined as a self-reported history of diabetes, the use of antidiabetic medication, or HbA1c levels ≥6.5%. Among 6,786 enrolled participants aged 40 years and above, 734 were classified as diabetic (10.8%). After adjusting for several confounders, the IOP values were significantly higher in participants with diabetes than in those without diabetes (14.4 ± 0.1 vs. 13.9 ± 0.1 mmHg, P < 0.001) and were also significantly increased in those with elevated HbA1c and serum glucose levels (both P < 0.001). Moreover, diabetes was significantly related to ocular hypertension (multivariable-adjusted odds ratio, 1.75; 95% confidence interval, 1.09–2.81; P < 0.05). The positive influence of diabetes with ocular hypertension was consistent even after adjustment for central corneal thickness. In conclusion, diabetes, elevated HbA1c, and increased serum glucose are significant contributing factors for elevated IOP.

Neurodegeneration in Alzheimer's disease and glaucoma: overlaps and missing links

The eye is said to be the window into the brain. Alzheimer’s disease (AD) and glaucoma both being diseases of the elderly, have several epidemiological and histological overlaps in pathogenesis. Both these diseases are neurodegenerative conditions. Over the years, a consensus has developed that both may be two ends of a singular spectrum of diseases. Epidemiological studies have shown that more Alzheimer’s patients may be suffering from glaucoma than general healthy population. Retinal ganglion cell damage is a characteristic of both diseases, along with discovery of amyloid-β and tau protein deposition in the retina and aqueous humor of eye. The latter two proteins are known to be pathognomonic of AD. Other pathways such as the insulin receptor pathway also seem to be affected in both diseases similarly. In spite of these overlaps, there are few missing links which still need more evidence, namely, intraocular pressure mechanisms, cerebrospinal fluid pressure and trans-lamina cribrosa pressure gradients, vascular autoregulation factors, etc. Several factors point towards a common pathogenesis at some level for both diseases and prospective studies are necessary to study the natural course of both diseases.

Sex hormone levels and risk of primary open-angle glaucoma in postmenopausal women

OBJECTIVE

We evaluated the relation of prediagnostic sex hormone levels in postmenopausal women with primary open-angle glaucoma (POAG) and intraocular pressure (IOP).

METHODS

Among postmenopausal participants of the Nurses' Health Study, POAG cases (n = 189; diagnosed 1990-2008) and controls (n = 189) were matched on age, fasting status, and postmenopausal hormone use at blood draw (1989-1990). Plasma concentrations of estrone sulfate, estradiol, testosterone, sex hormone binding globulin, and dehydroepiandrosterone sulfate were assessed. The primary outcome was POAG; in secondary analyses, among cases only, we evaluated maximum untreated IOP at diagnosis. Multivariable-adjusted logistic/multiple linear regression models were used to evaluate tertiles (Ts) of biomarker levels and the two outcomes, adjusting for various potential confounders.

RESULTS

We observed no significant associations of estrone, estradiol, sex hormone binding globulin, or dehydroepiandrosterone sulfate with POAG risk or with maximum IOP at glaucoma diagnosis among cases. Suggestive significant associations were observed with highest testosterone and POAG risk (T3 vs T1 multivariable-adjusted odds ratio 1.84; 95% confidence interval 1.02, 3.33; P trend 0.10). Similarly, for maximum IOP at diagnosis among cases only (mean 8 years after blood draw), higher testosterone was significantly associated with higher IOP (multivariable-adjusted difference in IOP T3 vs T1 2.17 mm Hg; 95% confidence interval 0.34, 3.99; P trend 0.02).

CONCLUSIONS

Overall, plasma sex hormone levels in postmenopausal women were not associated with POAG risk; however, a trend of higher testosterone levels being associated with higher POAG risk and higher IOP at diagnosis was observed and needs confirmation.

Examining the associations among intraocular pressure, hepatic steatosis, and anthropometric parameters

Emerging evidences had reported the positive relationship between obesity and intraocular pressure (IOP). The aim of the present study was to investigate the association between hepatic steatosis and IOP in an adult Taiwanese population.Seven thousand seven hundred twelve males and 6325 females who received a health examination at the Tri-Service General Hospital during the period from 2010 to 2016 were included in this study.IOP was measured by noncontact tonometry. Hepatic steatosis was diagnosed by abdominal ultrasound examination. Multivariate regression analyses were used to assess the associations among various anthropometric parameters and IOP.After adjusting for pertinent covariables, hepatic steatosis had a closer association with increased IOP than percentage body fat, body mass index, or waist circumference (β = 0.017, 95% confidence interval [CI] = 0.006, 0.028). This relationship remained significant among males in the study population (β = 0.015, 95% CI = 0.001, 0.029). Furthermore, hepatic steatosis was significantly correlated with increased risk of high IOP (odd ratios = 1.235, 95% CI = 1.041-1.465).Our study highlights that hepatic steatosis is a better index for assessing the relationship with increased IOP than other anthropometric parameters. Underlying pathophysiological mechanisms regulating the association between hepatic steatosis and increasing IOP and even the risk of glaucoma should be examined in further studies.

Cholinergic nervous system and glaucoma: From basic science to clinical applications

The cholinergic system has a crucial role to play in visual function. Although cholinergic drugs have been a focus of attention as glaucoma medications for reducing eye pressure, little is known about the potential modality for neuronal survival and/or enhancement in visual impairments. Citicoline, a naturally occurring compound and FDA approved dietary supplement, is a nootropic agent that is recently demonstrated to be effective in ameliorating ischemic stroke, traumatic brain injury, Parkinson's disease, Alzheimer's disease, cerebrovascular diseases, memory disorders and attention-deficit/hyperactivity disorder in both humans and animal models. The mechanisms of its action appear to be multifarious including (i) preservation of cardiolipin, sphingomyelin, and arachidonic acid contents of phosphatidylcholine and phosphatidylethanolamine, (ii) restoration of phosphatidylcholine, (iii) stimulation of glutathione synthesis, (iv) lowering glutamate concentrations and preventing glutamate excitotoxicity, (v) rescuing mitochondrial function thereby preventing oxidative damage and onset of neuronal apoptosis, (vi) synthesis of myelin leading to improvement in neuronal membrane integrity, (vii) improving acetylcholine synthesis and thereby reducing the effects of mental stress and (viii) preventing endothelial dysfunction. Such effects have vouched for citicoline as a neuroprotective, neurorestorative and neuroregenerative agent. Retinal ganglion cells are neurons with long myelinated axons which provide a strong rationale for citicoline use in visual pathway disorders. Since glaucoma is a form of neurodegeneration involving retinal ganglion cells, citicoline may help ameliorate glaucomatous damages in multiple facets. Additionally, trans-synaptic degeneration has been identified in humans and experimental models of glaucoma suggesting the cholinergic system as a new brain target for glaucoma management and therapy.

Gender Difference in Intraocular Pressure and Incidence of Metabolic Syndrome: A Community-Based Cohort Study in Matsu, Taiwan

Background: We aimed to assess the effect of intraocular pressure (IOP) on incident metabolic syndrome (MetS) using a longitudinal follow-up of screening cohort in contrast to most of previous studies addressing the association between both. Methods: The empirical data were derived from a community-based integrated screening program in Matsu during the period 2003 to 2010. A total of 1347 participants older than 30 years were enrolled in this study. With the enrollment of 1056 participants with MetS free at baseline, the cohort with IOP measurement in 2003 were followed up over time to identify incident MetS to elucidate the temporal sequence of both. Results: The statistically significant effect noted was that elevated IOP (≥15 mmHg vs. <15 mmHg) had 1.46-fold risk for developing incident MetS (adjusted relative ratio [aRR]: 1.46; 95% confidence interval [CI]: 1.08-1.99) for both sex combined, particularly in men (aRR: 1.66; 95% CI: 1.13-2.45) but not in women. The finding that elevated IOP occurred before the presence of high blood pressure was noted in both men and women, whereas men with elevated IOP may be concomitant with more individual components (severity) of MetS earlier than women with elevated IOP. Conclusions: Elevated IOP leading to the risk for incident or severe MetS was noted in men but not in women. Evidence on this temporal sequence revealed the possibility of showing signs of elevated IOP before the development of MetS, which indicates the necessity of monitoring IOP in routine health check-up for prevention of MetS-related chronic diseases.

Heterogeneity in arterial hypertension and ocular perfusion pressure definitions: Towards a consensus on blood pressure-related parameters for glaucoma studies

PURPOSE

Glaucoma studies have long taken into account the blood pressure (BP) status of patients. This study summarizes and evaluates the impact of the different criteria that have been used for BP-related variables in glaucoma research.

METHODS

Studies included in two meta-analyses that reviewed the role of BP in glaucoma were analyzed. Additional studies published after the search periods of the meta-analyses were also included. Criteria for the definition of arterial hypertension and other BP-related variables, such as mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP), were retrieved.

RESULTS

Sixty-four studies were evaluated. One-third used 140 mmHg as a systolic BP cut-off to define hypertension, 20% used 160 mmHg and the remaining half used various other criteria. Less than 20% of studies reported MAP and/or MOPP. While eight of the ten studies reporting MAP used a correct formula that only happened for five of the eleven studies reporting MOPP. Using as an example average blood pressure values, incorrectly used formulas could have led to an overestimation of more than 100% of the expected values.

CONCLUSION

Considerable heterogeneity exists in BP-related variables in glaucoma research and different definitions can lead to large disparities. Glaucoma research would benefit from a consensus regarding blood pressure parameters.

Exogenous influences on intraocular pressure

Intraocular pressure (IOP), the pressure within the eyeball, is a function mainly of the production and elimination of aqueous humour. Balanced IOP helps to maintain the eyeball contour, allowing proper refraction of light in the anterior segment of the eye. Increases in IOP can cause injury to the ocular structure, typically the optic nerve head and retinal ganglion cells. IOP increase, additionally, is a risk factor for glaucoma progression. However, it is not unusual that glaucoma worsens despite well-managed IOP; indeed, glaucoma can develop and progress even within the normal IOP range. IOP measured once during daytime office hours might not provide sufficient information for effective glaucoma management. In fact, IOP is not a fixed value but rather changes over time: it fluctuates with the intrinsic circadian rhythm and can also change in various lifestyle-related situations (eg, with body posture, during exercise, while holding breath and according to dietary habits). It is therefore worth exploring the various factors that can affect IOP and glaucoma risk. In this review, the various exogenous influences on IOP in the literature are 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.

Metabolic syndrome as a risk factor for high intraocular pressure: the Korea National Health and Nutrition Examination Survey 2008-2010

BACKGROUND

High intraocular pressure (IOP) is well established as the most significant risk factor for both the development and progression of primary open-angle glaucoma. Elevated IOP is more frequently seen in the presence of metabolic disturbances that are associated with the components of metabolic syndrome (MetS). The aim of this study was to investigate the association between ocular hypertension and MetS.

PATIENTS AND METHODS

We examined the relationship between ocular hypertension and MetS in 17,160 Korean adults without glaucoma aged >19 years (7,368 men and 9,792 women) who participated in the 2008-2010 Korea National Health and Nutrition Examination Survey. Multivariate logistic regression analysis was used to assess the relationship between MetS and ocular hypertension, after adjusting for age, body mass index, smoking, alcohol consumption, and regular exercise.

RESULTS

The prevalence of MetS was 35.1% among males and 30.1% among females. The prevalence of ocular hypertension was 1.3% among males with MetS and 0.7% among females with MetS. Participants with MetS had a significantly higher IOP than those without MetS (P≤0.001), and each component of MetS had a different effect on the IOP. Hypertension was the strongest predictor of an elevated IOP. In multivariate regression analysis, ocular hypertension was significantly associated with MetS (P=0.027 for men; P=0.015 for women).

CONCLUSION

There is a statistically significant relationship between MetS and ocular hypertension.

Ascorbic acid metabolites are involved in intraocular pressure control in the general population

Elevated intraocular pressure (IOP) is an important risk factor for glaucoma. Mechanisms involved in its homeostasis are not well understood, but associations between metabolic factors and IOP have been reported. To investigate the relationship between levels of circulating metabolites and IOP, we performed a metabolome-wide association using a machine learning algorithm, and then employing Mendelian Randomization models to further explore the strength and directionality of effect of the metabolites on IOP. We show that O-methylascorbate, a circulating Vitamin C metabolite, has a significant IOP-lowering effect, consistent with previous knowledge of the anti-hypertensive and anti-oxidative role of ascorbate compounds. These results enhance understanding of IOP control and may potentially benefit future IOP treatment and reduce vision loss from glaucoma.

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Vitamin C and its metabolites are highly concentrated in human brain and eye tissues.

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Multi-omics analysis finds evidence for association between ascorbic acid metabolism and intraocular pressure.

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O-methylascorbate lowers intraocular pressure in the general population.

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O-methylascorbate's role in intraocular pressure regulation is likely mediated by its anti-photooxidative properties.

Systemic Disease and Long-term Intraocular Pressure Mean, Peak, and Variability in Nonglaucomatous Eyes

PURPOSE

Elevated intraocular pressure (IOP) is a well-known risk factor in glaucoma development and progression. As most glaucoma risk factors are not modifiable, IOP remains the sole focus of medical and surgical therapy. Identifying modifiable factors and their effects on IOP, such as systemic diseases, is therefore of interest. The objective is to assess the long-term, longitudinal relationship between systemic diseases and IOP mean, peak, and variability, including diabetes, hypertension, body mass index (BMI), and smoking status.

DESIGN

Secondary analysis of randomized clinical trial data.

METHODS

Longitudinal IOP and systemic disease data from the Age-Related Eye Disease Study (AREDS), a randomized clinical trial of high-dose antioxidants, was analyzed.

STUDY POPULATION

A total of 3909 older participants without a reported diagnosis of glaucoma or glaucoma treatment during AREDS with up to 12 years of annual IOP and systemic disease data.

MAIN OUTCOME MEASURES

Independent systemic disease risk factors associated with IOP.

RESULTS

Univariate analysis identified numerous systemic disease factors associated with IOP mean, peak, and variability. Longitudinal adjusted models identified diabetes, obesity, and systolic hypertension as significantly associated with increased IOP, while systemic beta-blocker use was inversely associated.

CONCLUSIONS

Results demonstrate a relationship between multiple systemic diseases and IOP; moreover, they demonstrate that systemic diseases influence additional parameters beyond mean IOP, such as IOP peak and variability. Although only to be taken within the context of IOP, these population-level trends reveal potentially modifiable factors in IOP control, and are particularly important in the context of increasing obesity and diabetes prevalence rates in American adults.

Association Between Nonalcoholic Fatty Liver Disease and Intraocular Pressure in Korean Adults

PURPOSE

Elevated intraocular pressure (IOP) is an important modifiable risk factor predicting glaucoma progression. Recent studies have demonstrated that metabolic risk factors influence IOP. Nonalcoholic fatty liver (NAFLD) is an emerging chronic liver disease that is closely associated with metabolic syndrome, obesity, and type 2 diabetes. Therefore, we investigated the relationship between NAFLD and intraocular pressure in Korean adults.

PATIENTS AND METHODS

This retrospective cross-sectional study analyzed a total of 7681 participants who visited a local health promotion center. NAFLD was defined via ultrasonography and patients were classified into 3 groups based on severity: normal, mild, and moderate to severe. We conducted multiple logistic regression analysis to examine the relationship between NAFLD and high IOP. We additionally performed multiple linear regression analysis to investigate the independent association between NAFLD and mean IOP.

RESULTS

Mean IOP levels significantly and linearly increased with increasing NAFLD grades. Compared with normal, the odds ratio and 95% confidence intervals for high IOP were 1.09 (0.96-1.24) for mild NAFLD and 1.28 (1.12-1.48) for moderate to severe NAFLD after adjusting for confounding factors. NAFLD severity was noticed as an independent factor associated with mean IOP levels using stepwise and enter methods for multiple linear regression analyses.

CONCLUSIONS

NAFLD severity was associated with high IOP (>15 mm Hg) in Korean adults in a dose-dependent manner.