Associations with intraocular pressure in the Barbados Eye Study

Incidence of primary open angle glaucoma in the Andhra Pradesh Eye Disease Study (APEDS)

BACKGROUND

To report 15-year incidence rate of primary open angle glaucoma (POAG) in the Andhra Pradesh Eye Disease Study (APEDS).

METHODS

A population-based longitudinal study was carried out at three rural study sites. Phakic participants aged ≥40 years who participated at baseline (APEDS I) and the mean 15-year follow-up visit (APEDS III) were included. A comprehensive ophthalmic examination was performed on all participants. Mean intraocular pressure (IOP) was average of IOPs of right and left eyes. The definition of glaucoma was based on the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) classification. The main outcome measure was incidence of POAG during the follow-up period in participants without glaucoma or suspicion of glaucoma at baseline.

RESULTS

Data from the available and eligible participants from the original cohort (1241/2790; 44.4%) were analysed. The mean age (standard deviation) of participants at baseline was 50.2 (8.1) years; 580 (46.7%) were men. Thirty-six participants developed POAG [bilateral in 17 (47.2%)] over 15 years. The incidence rate of POAG per 100-person years (95% confidence interval) was 2.83 (2.6, 3.08). Compared to baseline, the reduction in mean IOP [median (range) mm Hg] was -0.75 (-7.5, 9) in participants with incident POAG and -2.5 (-14.5, 14.5) in those without. The inter-visit difference in mean IOP was a significant risk factor on logistic regression analysis.

CONCLUSION

We report the long-term incidence of POAG in rural India. A longitudinal change in IOP, specifically a less pronounced reduction in IOP with increasing age, was a novel risk factor.

Association Between Days of the Week and Intraocular Pressure: Japan Ningen Dock Study

PRCIS

The analysis of intraocular pressure (IOP) by day of the week using the mega database showed a periodic weekly pattern with the highest value on Monday.

PURPOSE

To evaluate IOP by the day of the week.

PATIENTS AND METHODS

Annual health checkup examinees between April 2014 and March 2015 were cross-sectionally evaluated. As a result, 655,818 participants [51.5±10.5 (range: 20-96) years, 40.1% women] from 103 medical centers were included. IOP was measured using a noncontact tonometer. The mean IOPs of each day of the week were compared using multiple comparison test and multiple linear regression analysis. Wednesday was set as the reference. Moreover, weekly IOP variations stratified by sex and age were also evaluated.

RESULTS

Mean IOPs from Monday to Sunday were 13.19±2.97, 13.06±2.92, 13.05±2.91, 13.05±2.92, 13.12±2.94, 13.10±2.96, and 13.16±2.78 mm Hg. IOP was significantly higher on Monday, Friday, and Saturday than those on Wednesday ( P <0.001, <0.001, 0.002). After adjusting for factors affecting IOP, the IOPs on Monday and Saturday were higher than those on Wednesday [β=0.097 (95% CI: 0.074-0.121), P <0.001; β=0.032 (95% CI: 0.005-0.059), P =0.019]. Men had significantly higher IOPs on Monday and Saturday than on Wednesday [β=0.142 (95% CI: 0.110-0.173), P <0.001; β=0.053 (95% CI: 0.017-0.089), P =0.004], whereas women did not have a significant trend. Participants aged below 65 years had higher IOPs on Monday ( P <0.001 in under 60 years; P =0.003 in 60-64 years), while those aged 65 years or older did not ( P =0.856).

CONCLUSION

IOP values may have a periodic weekly pattern. The high IOP on Monday was more pronounced in men aged less than 65 years.

Inventory of Ocular Pulse Amplitude Values in Healthy Subjects and Patients With Ophthalmologic Illnesses: Systematic Review and Meta-analysis

PURPOSE

Many studies have examined the ocular pulse amplitude (OPA) to better understand its physiology and clinical relevance, but the papers are scattered, not consistently indexed, and sometimes difficult to locate. We aimed to identify and summarize the relevant published evidence on OPA and, in a meta-analysis, outline specific differences of this parameter between healthy individual, primary open-angle glaucoma, normal-tension glaucoma, ocular hypertension, and cataract patients.

DESIGN

Systematic review and meta-analysis.

METHODS

A thorough literature search and data extraction were conducted by 2 reviewers independently. Reports on OPA measured by the dynamic contour tonometry in conjunction with different ocular and systemic diseases or potential influencing factors were included.

RESULTS

Of the 527 initially found reports, 97 met the inclusion criteria assessing 31 clinical conditions. A meta-analysis based on 6850 eyes and 106 study arms (68.8%) revealed differences in mean OPA values in millimeters of mercury between various entities. Among healthy eyes, the OPA was 2.58 mm Hg (95% CI: 2.45-2.71), whereas OPA values were higher in glaucoma (unspecified glaucoma 2.73 mm Hg, 95% CI: 2.38-3.08; normal-tension glaucoma 2.66 mm Hg, 95% CI: 2.36-2.97; and primary open-angle glaucoma 2.92 mm Hg, 95% CI: 2.75-3.08). Although ocular hypertension showed the highest OPA values (3.53 mm Hg, 95% CI: 3.05-4.01), the lowest values were found in cataract eyes (2.26 mm Hg, 95% CI: 1.57-2.94).

CONCLUSION

We found different OPA values characteristic of different clinical entities, with above-normal values in glaucoma and ocular hypertension and lower values in cataract patients. Our work is intended for clinicians and researchers who want to get a quick overview of the available evidence or who need statistical data on OPA distributions in individual diseases.

Impact of smoking on glaucoma

PURPOSE OF REVIEW

Assessing whether lifestyle related factors play a role in causing primary open-angle glaucoma (POAG) is of great value to clinicians, public health experts and policy makers. Smoking is a major global public health concern and contributes to ocular diseases such as cataracts, and age-related macular degeneration through ischemic and oxidative mechanisms. Recently, smoking has been investigated as a modifiable risk factor for glaucoma. In the presence of an association with glaucoma, provision of advice and information regarding smoking to patients may help reduce the burden of disease caused by POAG. Therefore, the aim of this review is to summarize the current evidence regarding the effect of smoking in the pathogenesis of glaucoma and its incidence, progression as well as the benefits of smoking cessation.

RECENT FINDINGS

While the association between glaucoma development and smoking history is controversial, in the last decade, several recent studies have helped to identify possible effects of smoking, especially heavy smoking, in regard to glaucomatous progression. Smoking cessation may possibly be protective against glaucoma progression.

SUMMARY

Smoking may play a role in glaucoma progression and long-term smoking cessation may be associated with lower glaucoma progression. The dose-response relationship between smoking and glaucoma as well as therapeutic potential of smoking cessation needs to be further validated with both preclinical and rigorous clinical studies.

Predictors of Glaucomatous Progression in Individuals with Small and Large Optic Discs

PURPOSE

To identify factors associated with glaucomatous progression in individuals with small and large optic discs.

DESIGN

Retrospective review.

SUBJECTS

4505 individuals with glaucoma at UCLA; 233 (59.7%) with small discs, 157 (40.3%) with large discs.

METHODS

Small and large disc sizes were defined by OCT or Heidelberg Retinal Tomography as disc area ≤ 5% (≤ 1.3 mm2) and ≥ 95% (≥ 2.9 mm2), respectively. Medical records were reviewed for demographics, systemic comorbidities, glaucoma type, ocular comorbidities, and ocular surgery. Logistic regression was used to identify predictors of visual field (VF) progression in individuals with small and large discs and predictors of large versus small discs.

MAIN OUTCOME MEASURES

The VF deterioration with mean deviation, pointwise linear regression, and glaucoma rate index (GRI); large vs. small disc.

RESULTS

In individuals with small discs, Asian versus non-Hispanic White ethnicity was associated with increased progression (adjusted odds ratio [aOR] = 4.05; 95% confidence interval [CI] = 1.12-14.59 for GRI). Higher intraocular pressure (IOP) range and peak were associated with increased progression in individuals with both small discs (aOR = 1.12; 95% CI = 1.00-1.27 and aOR = 1.05; 95% CI = 1.00-1.10 per 1 mmHg for range and peak with GRI) and large discs (aOR = 1.35; 95% CI = 1.12-1.66 and aOR = 1.11; 95% CI = 1.03-1.20 per 1 mmHg for range and peak with GRI). Multivariable predictors of having large vs. small discs included vasospastic phenotype (aOR = 2.58; 95% CI = 1.35-5.19) and Black (aOR = 20.46; 95% CI = 8.33-61.84), Hispanic/Latino (aOR = 9.65; 95% CI = 4.14-25.39), Asian (aOR = 4.87; 95% CI = 2.96-8.1), and other (aOR = 2.79; 95% CI = 1.69-4.63) versus non-Hispanic White ethnicity.

CONCLUSIONS

Increased odds of glaucomatous progression were associated with Asian vs. non-Hispanic White ethnicity in glaucoma patients with small optic discs, as well as with increased IOP range and peak in those with small and large discs. Individuals with a vasospastic phenotype and those from racial and ethnic minority backgrounds had increased odds of having large vs. small optic discs. Further characterization of discernible phenotypes would improve disease prognostication and help individualize glaucoma treatment.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

[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.

Association Between Alcohol Consumption Patterns and Glaucoma in Japan

PRCIS

In this case-control study of the Japanese population, including 3207 glaucoma cases, alcohol consumption patterns such as frequency and quantity showed a positive association with glaucoma prevalence.

PURPOSE

To examine the association between alcohol consumption patterns and glaucoma.

SUBJECTS AND METHODS

This case-control study evaluated 3207 cases with glaucoma and 3207 matched controls. Patients over 40 years of age were included from 1,693,611 patients admitted to 34 hospitals in Japan. Detailed alcohol consumption patterns (drinking frequency, average daily drinks, and total lifetime drinks) were obtained, as well as various confounding factors, including smoking history and lifestyle-related comorbidities. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for glaucoma prevalence.

RESULTS

Drinking frequency showed an association with glaucoma for "a few days/week" (OR, 1.19; 95% CI, 1.03-1.38) and "almost every day/week" (OR, 1.40; 95% CI, 1.18-1.66). Average daily drinks showed an association for ">0-2 drinks/day" (OR, 1.16; 95% CI, 1.03-1.32). Total lifetime drinks showed an association for ">60-90 drink-year" (OR, 1.23; 95% CI, 1.01-1.49) and ">90 drink-year" (OR, 1.23; 95% CI, 1.05-1.44). As alcohol consumption levels differed considerably between men and women, additional analyses were conducted separately for men and women. Among men, drinking frequency of "a few days/week" and "almost every day/week," average daily drinks of ">0-2 drinks/day" and ">2-4 drinks/day," and total lifetime drinks of ">60-90 drink-year" and ">90 drink-year" had an association with glaucoma. Conversely, among women, neither drinking frequency, average daily drinks, nor total lifetime drinks were associated.

CONCLUSIONS

Both the frequency and quantity of alcohol consumption were associated with glaucoma. Further research on gender differences is warranted.

Associations of smoking and alcohol consumption with the development of open angle glaucoma: a retrospective cohort study

OBJECTIVES

To investigate the associations of alcohol consumption and smoking with the development of perimetric glaucoma in patients with suspected glaucoma.

DESIGN

A retrospective cohort study of patients suspected to have glaucoma enrolled in the Diagnostic Innovations in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (ADAGES).

SETTING

Three tertiary glaucoma centres in the USA.

PARTICIPANTS

825 eyes of 610 patients with glaucoma suspect eyes with normal visual fields (VF) at baseline were followed over an average of 9 years from the DIGS and ADAGES studies.

OUTCOME MEASURES

Development of glaucoma was defined as occurrence of three consecutive abnormal VF tests during follow-up. Univariable and multivariable Cox regression models were used to investigate lifestyle-related factors associated with development of VF loss over time.

RESULTS

VF tests were abnormal three times in a row in 235 (28.5%) eyes. Alcohol consumption was associated with a higher risk of developing glaucoma (HR 1.57, 95% CI 1.03 to 2.38, p=0.037). In men, the risk of developing glaucoma in alcohol drinkers (HR 1.92, 95% CI 1.00 to 3.68, p=0.048) was greater than non-alcohol drinkers. In individuals of African descent, the risk of developing glaucoma in alcohol drinkers (HR 1.79, 95% CI 1.02 to 3.15, p=0.043) was greater than non-alcohol drinkers. Age was a modifier of the relationship between smoking and glaucomatous VF defects (p=0.048). The risk of developing glaucoma in smokers (HR 1.73, 95% CI 1.10 to 2.72, p=0.019) was greater than never smokers after adjustment for confounding factors in older patients (age >61 years).

CONCLUSION

Alcohol consumption was associated with an increased risk of developing glaucoma, particularly in men and individuals of African descent. The risk of developing glaucoma among smokers suspected of having glaucoma was influenced by age, with older individuals having a higher risk than younger people.

TRIAL REGISTRATION NUMBER

NCT00221897 and NCT00221923.

Towards modifying the genetic predisposition for glaucoma: An overview of the contribution and interaction of genetic and environmental factors

Glaucoma, the leading cause of irreversible blindness worldwide, is a complex human disease, with both genetic and environmental determinants. The availability of large-scale, population-based cohorts and biobanks, combining genotyping and detailed phenotyping, has greatly accelerated research into the aetiology of glaucoma in recent years. Hypothesis-free genome-wide association studies have furthered our understanding of the complex genetic architecture underpinning the disease, while epidemiological studies have provided advances in the identification and characterisation of environmental risk factors. It is increasingly recognised that the combined effects of genetic and environmental factors may confer a disease risk that reflects a departure from the simple additive effect of the two. These gene-environment interactions have been implicated in a host of complex human diseases, including glaucoma, and have several important diagnostic and therapeutic implications for future clinical practice. Importantly, the ability to modify the risk associated with a particular genetic makeup promises to lead to personalised recommendations for glaucoma prevention, as well as novel treatment approaches in years to come. Here we provide an overview of genetic and environmental risk factors for glaucoma, as well as reviewing the evidence and discussing the implications of gene-environment interactions for the disease.

The Association of Alcohol Consumption with Glaucoma and Related Traits: Findings from the UK Biobank

PURPOSE

To examine the associations of alcohol consumption with glaucoma and related traits, to assess whether a genetic predisposition to glaucoma modified these associations, and to perform Mendelian randomization (MR) experiments to probe causal effects.

DESIGN

Cross-sectional observational and gene-environment interaction analyses in the UK Biobank. Two-sample MR experiments using summary statistics from large genetic consortia.

PARTICIPANTS

UK Biobank participants with data on intraocular pressure (IOP) (n = 109 097), OCT-derived macular inner retinal layer thickness measures (n = 46 236) and glaucoma status (n = 173 407).

METHODS

Participants were categorized according to self-reported drinking behaviors. Quantitative estimates of alcohol intake were derived from touchscreen questionnaires and food composition tables. We performed a 2-step analysis, first comparing categories of alcohol consumption (never, infrequent, regular, and former drinkers) before assessing for a dose-response effect in regular drinkers only. Multivariable linear, logistic, and restricted cubic spline regression, adjusted for key sociodemographic, medical, anthropometric, and lifestyle factors, were used to examine associations. We assessed whether any association was modified by a multitrait glaucoma polygenic risk score. The inverse-variance weighted method was used for the main MR analyses.

MAIN OUTCOME MEASURES

Intraocular pressure, macular retinal nerve fiber layer (mRNFL) thickness, macular ganglion cell-inner plexiform layer (mGCIPL) thickness, and prevalent glaucoma.

RESULTS

Compared with infrequent drinkers, regular drinkers had higher IOP (+0.17 mmHg; P < 0.001) and thinner mGCIPL (-0.17 μm; P = 0.049), whereas former drinkers had a higher prevalence of glaucoma (odds ratio, 1.53; P = 0.002). In regular drinkers, alcohol intake was adversely associated with all outcomes in a dose-dependent manner (all P < 0.001). Restricted cubic spline regression analyses suggested nonlinear associations, with apparent threshold effects at approximately 50 g (∼6 UK or 4 US alcoholic units)/week for mRNFL and mGCIPL thickness. Significantly stronger alcohol-IOP associations were observed in participants at higher genetic susceptibility to glaucoma (Pinteraction < 0.001). Mendelian randomization analyses provided evidence for a causal association with mGCIPL thickness.

CONCLUSIONS

Alcohol intake was consistently and adversely associated with glaucoma and related traits, and at levels below current United Kingdom (< 112 g/week) and United States (women, < 98 g/week; men, < 196 g/week) guidelines. Although we cannot infer causality definitively, these results will be of interest to people with or at risk of glaucoma and their advising physicians.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Estimation of Physiologic Pressures: Invasive and Non-Invasive Techniques, AI Models, and Future Perspectives

The measurement of physiologic pressure helps diagnose and prevent associated health complications. From typical conventional methods to more complicated modalities, such as the estimation of intracranial pressures, numerous invasive and noninvasive tools that provide us with insight into daily physiology and aid in understanding pathology are within our grasp. Currently, our standards for estimating vital pressures, including continuous BP measurements, pulmonary capillary wedge pressures, and hepatic portal gradients, involve the use of invasive modalities. As an emerging field in medical technology, artificial intelligence (AI) has been incorporated into analyzing and predicting patterns of physiologic pressures. AI has been used to construct models that have clinical applicability both in hospital settings and at-home settings for ease of use for patients. Studies applying AI to each of these compartmental pressures were searched and shortlisted for thorough assessment and review. There are several AI-based innovations in noninvasive blood pressure estimation based on imaging, auscultation, oscillometry and wearable technology employing biosignals. The purpose of this review is to provide an in-depth assessment of the involved physiologies, prevailing methodologies and emerging technologies incorporating AI in clinical practice for each type of compartmental pressure measurement. We also bring to the forefront AI-based noninvasive estimation techniques for physiologic pressure based on microwave systems that have promising potential for clinical practice.

10 Years of GWAS in intraocular pressure

Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma, the leading cause of irreversible blindness worldwide. In this review, we summarize the findings of genome-wide association studies (GWASs) of IOP published in the past 10 years and prior to December 2022. Over 190 genetic loci and candidate genes associated with IOP have been uncovered through GWASs, although most of these studies were conducted in subjects of European and Asian ancestries. We also discuss how these common variants have been used to derive polygenic risk scores for predicting IOP and glaucoma, and to infer causal relationship with other traits and conditions through Mendelian randomization. Additionally, we summarize the findings from a recent large-scale exome-wide association study (ExWAS) that identified rare variants associated with IOP in 40 novel genes, six of which are drug targets for clinical treatment or are being evaluated in clinical trials. Finally, we discuss the need for future genetic studies of IOP to include individuals from understudied populations, including Latinos and Africans, in order to fully characterize the genetic architecture of IOP.

Prevalence of Glu323Lys Mutation of the TIGR/MYOC Gene and Risk Factors amongst Primary Open-angle Glaucoma Patients in Ouagadougou, Burkina Faso

Aim

Glaucoma is a group of degenerative diseases of the optic nerve whose predisposing factors may be genetic. The objective of this study was to estimate the frequency of the Glu323Lys mutation as a genetic risk factor for glaucoma.

Materials and methods

A cross-sectional study over 6 months from October 2020 to March 2021 in Ouagadougou, Burkina Faso. A total of 89 samples of patients with primary open-angle glaucoma (POAG) were collected. The frequency of the Glu323Lys mutation of the myocilin, trabecular meshwork inducible glucocorticoid response (TIGR/MYOC) gene by polymerase chain reaction (PCR)-restriction fragment length polymorphism.

Results

In glaucoma patients, only homozygous nonmutated guanine-guanine (GG) and heterozygous mutated adenine-guanine (AG) genotypes were found in 96.63 and 3.37% of cases, respectively. Around 69.66% of patients had a family history of glaucoma, 28.09% had a history of hypertension, and 7.86% had a history of diabetes.

Conclusion

The frequency of the Glu323Lys mutation of the TIGR/MYOC gene was 3.37% in the glaucoma population in Ouagadougou. A case-control study is necessary to know the contribution of the Glu323Lys mutation as a genetic risk factor for glaucoma in our study population.

Clinical significance

This study constituted the beginning of genetic investigations of glaucoma in our context and showed a low Glu323Lys mutation.

How to cite this article

Traoré L, Sanou J, Bakyono BS, et al. Prevalence of Glu323Lys Mutation of the TIGR/MYOC Gene and Risk Factors amongst Primary Open-angle Glaucoma Patients in Ouagadougou, Burkina Faso. J Curr Glaucoma Pract 2023;17(2):79-84.

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.

Smoking and environmental tobacco smoke exposure: implications in ocular disorders

PURPOSE

This article aims to gather and review the available knowledge on several implications of smoking and environmental tobacco smoke (ETS) exposure in ocular disorders and provides pathomechanistic insights where applicable.

MATERIALS AND METHODS

PubMed and Scopus databases were searched for relevant studies on the association of smoking and ETS exposure with various ocular disorders. Studies with different evidence levels, e.g., in-vivo, case-control, cohort, and meta-analysis, were included.

RESULTS

Smoking is an established, modifiable risk factor in several ocular diseases, including cataract, age-related macular degeneration, and Graves' ophthalmopathy; smokers are subject to more severe disease courses and less favorable treatment outcomes. Uveitis is twice as likely in smokers; smoking may also delay its resolution. Smoking and ETS exposure are major risk factors for diseases of other organs, with associated ocular complications as well, such as diabetes mellitus. ETS exposure is also associated with ocular surface pathologies, including dry eye syndrome. In children, early-life ETS exposure and maternal smoking during pregnancy are strongly associated with refractive errors and strabismus. Currently, available data on potential risks attributable to ETS exposure regarding ocular diseases are scarce and, in some instances, controversial.

CONCLUSION

In addition to smoking, ETS exposure is also a significant public health concern with possible links to several ocular diseases. However, the level of education of at-risk populations in this regard does not match the strength of the evidence.

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.

Age-Related Changes in Intraocular Pressure: Japan Ningen Dock Study

PRCIS

The analysis of intraocular pressure by age using a mega database showed a consistent age-related intraocular pressure decrease.

PURPOSE

To clarify the association between age and intraocular pressure (IOP), the IOP value by age was assessed using a large IOP database.

MATERIALS AND METHODS

This cross-sectional study was conducted among 103 health checkup institutions registered to the Japan Society of Ningen Dock, and included participants who underwent annual health checkups between April 2014 and March 2015. The inclusion criteria were as follows: complete data for IOP in eyes, body mass index, waist circumference, blood pressure, hemoglobin A1c, and a self-administered health questionnaire. A total of 655,818 participants were enrolled. The mean age was 51.5±10.5 years (range, 20-96 y), and 40.1% were women. IOP was measured using a noncontact tonometer. Multiple linear regression analysis was conducted to explore factors associated with IOP, including age, and analyses stratified by age group: <40, 40-69, and ≥70 years.

RESULTS

A consistent negative association between IOP and age [β=-0.353 (95% confidence interval: -0.360--0.346)] was observed. In the age groups of <40 and ≥70 years, the age-related IOP decline was more pronounced [β=-0.502 (95% CI: -0.566 to -0.439); β=-0.674 (95% CI: -0.753 to -0.595)], with it being 14.21±2.95 and 11.18±2.52 mm Hg in the 20-24 and 90-96 year age groups, respectively. The middle-aged (aged 40-69 y) population showed gradual decline [β=-0.313 (95% CI: -0.323 to -0.303)].

CONCLUSION

Age was strongly and negatively associated with IOP. The magnitude of IOP decline across lifespans was ∼3 mmHg. Age-related decreases in IOP were nonlinear and phasic.

Changes in intraocular pressure after pharmacological pupil dilatation in an elderly Chinese population in Taiwan: The Shihpai eye study

BACKGROUND

Mydriatic drugs are often used in ophthalmic clinics for pupil dilatation to assess the optic nerve and retina. Clinical studies have indicated that an increase in intraocular pressure (IOP) after pupil dilation is noted in open-angle glaucoma patients, those with narrow angles and in normal subjects. Asians are more likely to have narrow angles. Moreover, age-related cataract may increase the crowdedness of the angle. This study aimed to assess the effects of mydriatic pupil dilatation on IOP in an elderly Chinese population.

METHODS

The Shihpai Eye Study was a community-based, cross-sectional survey of vision and eye diseases among noninstitutionalized subjects aged 65 years and older in Shihpai, Taipei, Taiwan. IOP was taken using noncontact tonometry. The pupil was dilated with 1% tropicamide. IOP was measured again after maximal pupil dilatation 1 hour after mydriasis.

RESULTS

Of the 2045 participants, 1361 (66.6%) participated in both the questionnaire and eye examinations. The mean IOP before pupil dilatation was 12.9 ± 3.1 mmHg and was 12.8 ± 3.4 mmHg (range: 5-36 mmHg) after pupil dilatation. IOP higher than 21 mmHg after pupil dilation was noted in 17 (1.34%) participants, of whom IOP exceeded 30 mmHg in two (0.16%). Overall, the changes in IOP before and after pupil dilatation were insignificant ( p = 0.04). In the final regression analyses, refractive status toward hyperopia ( p < 0.01) was the only significant factor associated with an increase in IOP of at least 4 mmHg after pupil dilatation.

CONCLUSION

Our results revealed that the increase in IOP after pharmacological pupil dilatation was minimal, and the incidence of acute angle-closure attack was insignificant. Hyperopic status was the only factor related to an increase in IOP of > 4 mmHg. Caution should be exercised if one is hyperopic or has a history of glaucoma and rechecking IOP in these subjects is suggested after pharmacological mydriasis.

Dietary Nitrate Intake Is Associated with Decreased Incidence of Open-Angle Glaucoma: The Rotterdam Study

Previous studies suggest that nitric oxide is involved in the regulation of the intraocular pressure (IOP) and in the pathophysiology of open-angle glaucoma (OAG). However, prospective studies investigating the association between dietary nitrate intake, a source of nitric oxide, and incident (i)OAG risk are limited. We aimed to determine the association between dietary nitrate intake and iOAG, and to evaluate the association between dietary nitrate intake and IOP. From 1991 onwards, participants were followed each five years for iOAG in the Rotterdam Study. A total of 173 participants developed iOAG during follow-up. Cases and controls were matched on age (mean ± standard deviation: 65.7 ± 6.9) and sex (%female: 53.2) in a case:control ratio of 1:5. After adjustment for potential confounders, total dietary nitrate intake was associated with a lower iOAG risk (odds ratio (OR) with corresponding 95% confidence interval (95% CI): 0.95 (0.91-0.98) for each 10 mg/day higher intake). Both nitrate intake from vegetables (OR (95% CI): 0.95 (0.91-0.98) for each 10 mg/day higher intake) and nitrate intake from non-vegetable food sources (OR (95% CI): 0.63 (0.41-0.96) for each 10 mg/day higher intake) were associated with a lower iOAG risk. Dietary nitrate intake was not associated with IOP. In conclusion, dietary nitrate intake was associated with a reduced risk of iOAG. IOP-independent mechanisms may underlie the association with OAG.

The Impact of Systemic Health Parameters on Intraocular Pressure in the Western Region of Saudi Arabia

Background

A normal intraocular pressure (IOP) is essential for maintaining the normal structure and function of the eyes. Furthermore, an elevated IOP is a known risk factor for glaucoma. As the results from studies addressing the relationship between IOP and systemic health parameters are conflicting, researchers have not reached a consensus. This study aimed to evaluate the relationship between IOP and health parameters among non-glaucomatous participants in the western region of Saudi Arabia.

Method

We retrospectively reviewed the medical records of 255 participants aged 20 years and above who had not received any medical treatment for ocular hypertension or glaucoma at King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia, from January 2019 to April 2021. The patients were categorized into age groups, divided by decades (ranging from 20-29 years to 80+ years); the most prevalent age group was 60-69 years. The data were entered using Microsoft Excel 2016 (Microsoft Corporation, Redmond, Washington), and Statistical Package for the Social Sciences (SPSS) software was used for univariate analysis. The relationship between continuous variables was analyzed by the Pearson correlation coefficient. The differences between continuous and categorical variables were assessed by the t-test and one-way analysis of variance (ANOVA) test, respectively.

Results

The mean (standard deviation) IOP in the right and the left eyes was 15.7 mmHg (4.0) and 15.6 mmHg (3.9), respectively. There were no significant associations between IOP and lipid profile parameters (p > 0.05). There was a statistically significant difference in the right IOP, in relation to the age groups (p = 0.006). Moreover, the mean IOP in the left eye was significantly higher among patients with diabetes than in the patients without diabetes (p = 0.007) as well as in patients with hypertension than in the patients without hypertension (p = 0.023).

Conclusion

The effect of total cholesterol, triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), BMI, and sex on IOP could not be established in our study. However, over the past years, people's diets have incorporated higher cholesterol and fat content, leading to higher BMI levels. Therefore, further studies of the association between BMI and IOP are critical to determine if BMI is certainly a significant risk factor for increased IOP and glaucoma.

Asian Race and Primary Open-Angle Glaucoma: Where Do We Stand?

Primary open-angle glaucoma (POAG) is an optic neuropathy characterized by irreversible retinal ganglion cell damage and visual field loss. The global POAG prevalence is estimated to be 3.05%, and near term is expected to significantly rise, especially within aging Asian populations. Primary angle-closure glaucoma disproportionately affects Asians, with up to four times greater prevalence of normal-tension glaucoma reported compared with high-tension glaucoma. Estimates for overall POAG prevalence in Asian populations vary, with Chinese and Indian populations representing the majority of future cases. Structural characteristics associated with glaucoma progression including the optic nerve head, retina, and cornea are distinct in Asians, serving as intermediates between African and European descent populations. Patterns in IOP suggest some similarities between races, with a significant inverse relationship between age and IOP only in Asian populations. Genetic differences have been suggested to play a role in these differences, however, a clear genetic pattern is yet to be established. POAG pathogenesis differs between Asians and other ethnicities, and it may differ within the broad classification of the Asian race. Greater awareness and further research are needed to improve treatment plans and outcomes for the increasingly high prevalence of normal tension glaucoma within aging Asian populations.

Effects of aging and exercise habits on blood flow profile of the ocular circulation

Purpose

We examined the effects of aging and exercise habits on the ocular blood flow (OBF) and its profiles throughout the optic nerve head region and choroidal area. We hypothesized that exercise habits reduce the stiffness of vessels in the ocular circulation, which generally increases with aging.

Methods

Participants in a medical checkup program (698 males and 192 females aged 28 to 80 years) were categorized into 2 groups (with and without exercise habits) based on participant self-reporting and the definition of the Ministry of Health, Labor and Welfare of Japan (MHLW). OBF in the right eye was measured and analyzed using laser speckle flowgraphy. The blowout time (BOT), which is the time during which the blood flow is higher than half of the mean of the minimum and maximum signals during one heartbeat, was calculated as an index of the blood flow profile. BOT has been used as an indicator of the flexibility of blood vessels.

Results

BOT significantly decreased with aging. Neither the self-reported nor MHLW-based exercise habits significantly affected the ocular circulation.

Conclusion

These results indicate that the stiffness of the ocular vessels increases with aging, and this cannot be prevented by exercise habits.

Intraocular Pressure and Its Relation to Ocular Geometry: Results From the Gutenberg Health Study

Purpose

The purpose of this study was to investigate the association between intraocular pressure (IOP) and ocular geometry.

Methods

The Gutenberg Health Study is a population-based cohort study in Mainz, Germany. Study participants underwent a comprehensive ophthalmologic examination including noncontact tonometry, objective refraction, optical biometry, and Scheimpflug imaging of the anterior segment at the first 5-year follow-up examination (in 2012–2017). Multivariable linear regression analysis was carried out to determine associations of IOP and geometric parameter of the human phakic eye, namely central corneal thickness (CCT), corneal curvature, anterior chamber depth (ACD), lens thickness, and axial length. In addition, the relationship of IOP and the anterior chamber angle (ACA) width was analyzed.

Results

There were 6640 participants with phakia (age 57.3 ± 10.2 years, 49.1% women) that were included in this cross-sectional analysis. Mean IOP was 14.8 ± 2.9 mm Hg in the right eyes and 14.9 ± 2.9 mm Hg in the left eyes. IOP increased with higher CCT, greater posterior segment length, higher age (all P < 0.001), thicker lens (P = 0.003), and female sex (P = 0.05), whereas the ACD was not associated with higher IOP. The IOP increased with a narrower ACA in univariable analysis (P < 0.001), but not in adjusted analysis in subjects with an open angle.

Conclusions

IOP values are related to ocular geometry, as shown in this population-based study on Caucasian subjects. Thus, knowledge of the architecture of the eye is an important factor when measuring IOP. Longitudinal evaluation will analyze whether some of these parameters are also risk factors for the development of glaucoma.

Alcohol, intraocular pressure and open-angle glaucoma: A systematic review and meta-analysis

Topic

This systematic review and meta-analysis summarizes the existing evidence for the association of alcohol use with intraocular pressure (IOP) and open-angle glaucoma (OAG).

Clinical Relevance

Understanding and quantifying these associations may aid clinical guidelines or treatment strategies and shed light on disease pathogenesis. The role of alcohol, a modifiable factor, in determining IOP and OAG risk also may be of interest from an individual or public health perspective.

Methods

The study protocol was preregistered in the Open Science Framework Registries (https://osf.io/z7yeg). Eligible articles (as of May 14, 2021) from 3 databases (PubMed, Embase, Scopus) were independently screened and quality assessed by 2 reviewers. All case-control, cross-sectional, and cohort studies reporting a quantitative effect estimate and 95% confidence interval (CI) for the association between alcohol use and either IOP or OAG were included. The evidence for the associations with both IOP and OAG was qualitatively summarized. Effect estimates for the association with OAG were pooled using random effects meta-analysis. Studies not meeting formal inclusion criteria for systematic review, but with pertinent results, were also appraised and discussed. Certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework.

Results

Thirty-four studies were included in the systematic review. Evidence from 10 studies reporting an association with IOP suggests that habitual alcohol use is associated with higher IOP and prevalence of ocular hypertension (IOP > 21 mmHg), although absolute effect sizes were small. Eleven of 26 studies, comprising 173 058 participants, that tested for an association with OAG met inclusion criteria for meta-analysis. Pooled effect estimates indicated a positive association between any use of alcohol and OAG (1.18; 95% confidence interval [CI], 1.02–1.36; P = 0.03; I² = 40.5%), with similar estimates for both prevalent and incident OAG. The overall GRADE certainty of evidence was very low.

Conclusions

Although this meta-analysis suggests a harmful association between alcohol use and OAG, our results should be interpreted cautiously given the weakness and heterogeneity of the underlying evidence base, the small absolute effect size, and the borderline statistical significance. Nonetheless, these findings may be clinically relevant, and future research should focus on improving the quality of evidence.

Effect of Blood Pressure Reduction on Intraocular Pressure and Ophthalmic Artery Blood Flow Velocity in Hypertension

Purpose: To evaluate the effect of reducing blood pressure (BP) by atenolol and amlodipine on (1) intraocular pressure (IOP) and (2) ophthalmic artery blood flow (OAF) velocity in new hypertensives. Methods: A prospective, observational cohort study conducted at a tertiary care center in India after IRB approval. New hypertensives treated with atenolol 25 mg or amlodipine 5 mg were divided into 2 groups of 30 patients each. BP, IOP by Goldmann applanation tonometry and OAF velocity by transcranial doppler sonography was performed before medication and post medication on day 1, 7, and 30. Results: There was a significant decrease in IOP with both drugs; the effect was greater with atenolol. Atenolol: premedication IOP - 16.06 ± 2.13 mmHg and day 30-12.46 ± 1.94 (22.4%) [P < 0.001], amlodipine: premedication IOP-15.13 ± 2.55 mmHg and day 30- 13.06 ± 2.14 (13.68%) [P < 0.001]. A decrease of 0.5 mmHg in IOP with every 10 mmHg (95% CI: 0.121-0.826, P value = 0.01) decrease in systolic BP was noted after oral atenolol. The OAF peak systolic velocity and mean flow velocity were equally reduced with both drugs (P < 0.001). The end-diastolic velocity, reduced only with atenolol (P = 0.049) but returned to baseline with amlodipine at 1 month. Conclusions: BP reduction by atenolol and amlodipine led to decreases in IOP and OAF velocity, greater with atenolol. The IOP decrease was likely due to reduced blood flow. A slight decrease in the diastolic flow of the ophthalmic artery was noted with atenolol.

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.

Mechanistic links between systemic hypertension and open angle glaucoma

Systemic hypertension or hypertension is a very common chronic age-related disease worldwide. It is typically characterised by a sustained elevation of blood pressure, particularly when the systolic blood pressure and/or diastolic blood pressure are of more than 140 mmHg and 90 mmHg, respectively. If hypertension is not well controlled, it may lead to an increased risk of stroke and heart attack. It has been shown that hypertension is linked to various ocular diseases, including cataract, diabetic retinopathy, age-related macular degeneration, and glaucoma. Glaucoma is the leading cause of irreversible blindness worldwide. Primary open angle glaucoma is the most common form of the disease and is usually characterised by an increase in intraocular pressure. This condition, together with normal tension glaucoma, constitutes open angle glaucoma. Systemic hypertension has been identified as a risk factor for open angle glaucoma. It is speculated that blood pressure is involved in the pathogenesis of open angle glaucoma by altering intraocular pressure or ocular blood flow, or both. Recent evidence has shown that both extremely high and low blood pressure are associated with increased risk of open angle glaucoma. Additional pathogenic mechanisms, including increased inflammation likely to be involved in the development and progression of these two diseases, are discussed.

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.

Gout and open-angle glaucoma risk in a veteran population

PURPOSE

A history of gout, arthritis due to hyperuricemia, has been associated with decreased risk for neurodegenerative diseases such as Parkinson's disease. We performed a population-based case-control study in the US Department of Veterans Affairs (VA) medical centers nationwide to assess if gout or hyperuricemia is similarly associated with the ocular neurodegenerative condition glaucoma.

METHODS

We used ICD-9 codes to identify a nationwide cohort of patients examined at VA healthcare eye clinics between 2000 and 2015 with a diagnosis of open-angle glaucoma (OAG) or of glaucoma suspect. We used incidence density matching to choose controls. We used multivariable logistic regression to examine associations between a history of gout and uric acid (UA) levels on relative risk of OAG or glaucoma suspect.

RESULTS

There were 1,144,428 OAG or glaucoma suspect cases and 1,144,428 matched controls. Veterans with a history of gout had a small significant decreased risk of OAG compared to controls (OR_{adjusted(adj)} = 0.985, 95% CI: 0.974-0.996). Treated gout was similarly associated with small decreased risk (OR_adj = 0.963, 95% CI: 0.950-0.976). A small subset of patients (11.9% of cases and 13.2% of controls) had UA labs available; veterans with the highest median UA levels (> 7.29 mg/dL) did not have statistically significant differences in relative OAG risk (OR_adj = 1.014, 95% CI: 0.991-1.036).

CONCLUSION

Prospective research in other cohorts is needed to confirm our findings in veterans suggesting a history of gout is associated with a small decreased relative risk of glaucoma.

Does body position, age, and heart rate induce IOP's changes?

OBJECTIVES

The main goal of this research was to determine the differences between the values of intraocular pressure (IOP) in the supine and sitting positions, and to assess the effect of age and cardiovascular parameters.

METHODS

Seventy-two healthy adults were enrolled and classified into age groups: 20-30 years (group A), 31-40 years (group B), and 41-71 years (group C). Corneal biometry and cardiovascular parameters, such as heart rate (HR), were measured. IOP measurements were taken in the sitting position (IOP_S) and in the supine position (IOP_L) using the iCare^® Pro tonometer.

RESULTS

A significant difference between the IOP_S and IOP_L in the entire cohort was found (p < 0.001). Regarding the age subgroups, a significant difference (p < 0.001) between the IOP_S and IOP_L was obtained in group A (2.6 ± 1.6 mmHg) and group C (1.5 ± 1.3 mmHg). There were no significant differences in the IOP_S between groups. The highest IOP values were obtained for group A. The correlations between HR and IOP_S are statistically significant for group A and group B, and for HR and IOP_L-S for group B only. Multivariate analysis showed that HR has a significant influence on the difference in IOP in the two body positions.

CONCLUSION

A statistically significant difference between the effect of age and the values of IOP_S and IOP_L was shown. Cardiovascular parameters showed some relevant statistical dependencies, but with a rather marginal significance in young people. The influence of body position for the measurement of IOP for healthy subjects does not seem to matter, despite the fact that there are some dependencies that are statistically significant.

Alcohol and the Eye

In this article, we present a review of ocular conditions related to alcohol consumption. A search of the literature published from 1952 to March 2020 was performed. The titles and abstracts were screened and the eligible studies were selected. PubMed, ISI Web of Knowledge database, Scopus, Embase, and the Cochrane Library were searched. We categorized the relationship between alcohol intake and ocular conditions by the type of ocular exposure to alcohol. Accordingly, ocular findings following acute alcohol intoxication, optic neuropathy following methanol toxicity, congenital conditions related to maternal alcohol consumption, and ocular disease related to chronic alcoholism are discussed. The main feature of alcohol intoxication in the eye is abnormal eye movement. Acute optic neuropathy secondary to methyl alcohol consumption is a serious ocular disease with permanent vision loss or scotoma. Prenatal exposure to ethanol may end in fetal alcohol spectrum disease, where ocular findings are a constant component. The association between chronic alcohol consumption and increased risks of cataract, age-related macular degeneration, diabetic retinopathy, different types of optic neuropathy, impairment of visual quality, retinal vascular disease, and ocular surface disease has also been reported. Along with detrimental medical and social effects, the role of alcohol consumption in different ocular conditions should be considered, as alcohol-induced visual disturbances may contribute to the heavy burden of alcohol abuse on the healthcare system and overall quality of life.

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.

Home Self-tonometry Trials Compared with Clinic Tonometry in Patients with Glaucoma

PURPOSE

This study examined characteristics of intraocular pressure (IOP) as measured during home tonometry in comparison with in-clinic tonometry in patients with glaucoma.

DESIGN

Retrospective cross-sectional study of glaucoma patients who completed 1 week of self-tonometry at a single academic center.

PARTICIPANTS

Patients with glaucoma who completed home tonometry trials with the iCare HOME tonometer (iCare USA) for any reason.

METHODS

Home IOP measurements were compared with in-clinic tonometry performed during the 5 visits preceding home tonometry. Maximum daily IOP was correlated to time of day. Generalized estimating equations were used to evaluate patient characteristics and clinic-derived variables that predicted differences between home and clinic IOP.

MAIN OUTCOME MEASURES

IOP mean, maximum, minimum, range, standard deviation and coefficient of variation were compared between clinic and home tonometry. IOP mean daily maximum (MDM) and mean daily range were calulated to describe recurrent IOP spiking.

RESULTS

A total of 107 eyes from 61 patients were analyzed. Mean age was 63.2 years (standard deviation [SD], 14.0 years) and 59.0% were women. Mean clinic and home IOPs were 14.5 mmHg (SD, 4.7 mmHg) and 13.6 mmHg (SD, 5.1 mmHg). Home tonometry identified significantly higher maximum IOP, lower minimum IOP, and greater IOP range than clinic tonometry (P < 0.001). Maximum daily IOP occurred outside of clinic hours (8 am-5 pm) on 50% of days assessed and occurred between 4:30 am and 8 am on 24% of days. Mean daily maximum IOP exceeded maximum clinic IOP in 44% of patients and exceeded target IOP by 3 mmHg, 5 mmHg, or 10 mmHg in 31%, 15%, and 6% of patients, respectively. Patient characteristics that predicted significant deviations between MDM and mean clinic IOP or target IOP in multivariate models included younger age, male gender, and absence of prior filtering surgery.

CONCLUSIONS

Self-tonometry provides IOP data that supplements in-clinic tonometry and would not be detectable over daytime in-clinic diurnal curves. A subset of patients in whom home tonometry was ordered by their glaucoma clinician because of suspicion of occult IOP elevation demonstrated reproducible IOP elevation outside of the clinic setting. Such patients tended to be younger and male and not to have undergone previous filtering surgery.

Distribution of intraocular pressure and related risk factors in a highly myopic Chinese population: an observational, cross-sectional study

Clinical relevance: Those with high myopia are more likely to have glaucoma compared to those without myopia and intraocular pressure was a key factor for developing glaucoma. Thus, investigating the distribution of intraocular pressure and associated factors among those with high myopia is of high importance.Background: The aim of this work is to investigate the distribution of intraocular pressure and the correlated risk factors in a highly myopic Chinese population.Methods: A total of 884 Chinese participants with bilateral high myopia (≤ -6.00 D spherical power) were included from the Zhongshan Ophthalmic Center-Brien Holden Vision Institute High Myopia Cohort Study. All participants underwent a comprehensive ocular examination, including ocular biometry, cycloplegic refractometry, and intraocular pressure measurement with Goldmann applanation tonometry. Information on smoking and drinking status was also collected.Results: The mean spherical equivalence of left eyes was -10.02 ± 3.58 D with a mean axial length of 27.48 ± 1.55 mm. The overall mean intraocular pressure was 15.1 ± 2.4 mmHg (95% confidence interval, 15.0 to 15.3 mmHg). The intraocular pressure in the -6.00D to -7.99D spherical equivalence group, -8.00D to -9.99D spherical equivalence group, and ≤ -10.00 D group were 15.3 ± 2.4 mmHg, 15.1 ± 2.5 mmHg, and 15.0 ± 2.4 mmHg, respectively (p = 0.979). In multiple regression models, intraocular pressure in high myopes was not associated with spherical equivalence (p = 0.354) or axial length (p = 0.601), but significantly higher in those who were younger (non-standardised beta, -0.018; p = 0.007), smoked tobacco (non-standardised beta, 1.085; p = 0.001) and had greater central corneal thickness (non-standardised beta, 0.021; p < 0.001).Conclusion: Intraocular pressure was 15.1 ± 2.4 mmHg among subjects with a mean age of 22.8 years in this highly myopia Chinese population. These findings suggested that highly myopic Chinese persons of a younger age and greater central corneal thickness were more likely to have higher intraocular pressure.

Cutaneous melanin and glaucoma: a case control study

Purpose: Previous studies have used subjective assessments to implicate darker skin color as a risk factor for glaucoma. This study used objective measurements to determine whether skin melanin is a risk factor for glaucoma.Methods: In a case-control study conducted at a tertiary eye hospital in Nepal, patients aged 40 years or older from the glaucoma clinic were enrolled as cases and age-matched patients without glaucoma from other clinics at the eye hospital were enrolled as controls. A colorimeter was used to capture melanin measurements in triplicate from the inner arm and forehead of each participant. The exposure variable of interest was the median skin melanin value, in arbitrary units. The outcome of interest was the presence of glaucoma.Results: 100 glaucoma cases and 100 matched controls were enrolled. Agreement between the triplicate melanin measurements was high, with an intra-class correlation of 0.99 (95% CI, 0.99-0.99) for inner arm measurements and 0.97 (95% CI 0.96-0.98) for forehead measurements. Mean inner arm melanin values were 604 units (standard deviation [SD] 177) in cases and 602 units (SD 179) in controls; forehead values were 650 (SD 146) in cases and 652 (SD 152) in controls. After adjusting for sex and country of residence, skin melanin was not associated with the presence of glaucoma (odds ratio 1.04, 95%CI 0.78-1.38 for inner arm values and 0.97, 95%CI 0.70-1.35 for forehead values).Conclusion: This study failed to find a significant association between skin pigmentation and glaucoma.

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.

The Association of Intraocular Pressure With Obesity and Cardiometabolic Risk in a Young Farmworker Population

PRCIS

Intraocular pressure (IOP) was found to be significantly correlated with body mass index (BMI), waist circumference, and diastolic blood pressure (DBP) in a farmworker population located in the southeast Georgia, USA. BMI was correlated with IOP, independent of systemic blood pressures.

PURPOSE

Elevated IOP is a known risk factor for glaucomatous optic neuropathy and is believed to be associated with obesity and cardiometabolic diseases. The high prevalence of these conditions in the United States necessitates an evaluation of the relationship among obesity, cardiometabolic risks, and IOP among understudied younger populations.

MATERIALS AND METHODS

Farmworker data were collected from the annual Costa-Layman Health Fair between 2013 and 2017. Correlations of IOP with demographic factors, obesity, and cardiometabolic risks were analyzed using analysis of covariance, partial Pearson correlations, and linear regressions.

RESULTS

In the farmworker population (n=346), the mean IOP was 15.5 mm Hg and the prevalence of ocular hypertension (IOP>21 mm Hg) was 5.5%. BMI, waist circumference, and DBP were significantly correlated (r=0.192, P=0.001; r=0.128, P=0.017; r=0.142, P=0.007, respectively) with IOP when adjusted for age, sex, and ethnicity. Each 10 mm Hg increase in DBP corresponded with a 0.51 mm Hg increase in IOP. With adjustment for age, sex, ethnicity, systolic blood pressure, and DBP, BMI remained significantly correlated with IOP (r=0.166, P=0.002).

CONCLUSIONS

Higher IOP is associated with obesity measures including BMI and waist circumference and is correlated with DBP. These findings suggest that BMI is an independent risk factor for elevated IOP.

The Relationship Between Melanin and Glaucoma: A Case-control Study

PRéCIS:: In a case-control study, skin pigmentation was not statistically significantly different when comparing glaucoma patients to those without glaucoma.

PURPOSE

Darker skin color has been implicated as a risk factor for glaucoma based on previous studies' subjective assessments of skin pigmentation. This study used objective measurements to determine whether cutaneous pigmentation is a risk factor for glaucoma.

METHODS

This case-control study was conducted at Menelik II Tertiary Referral Hospital in Addis Ababa, Ethiopia. Patients aged 40 years or older from the glaucoma clinic who were being scheduled for trabeculectomy were enrolled as cases and age-matched patients without glaucoma from other clinics at Menelik II Tertiary Referral Hospital were enrolled as controls. A Dermacatch device was used to capture melanin measurements in triplicate from the inner arm of each participant. The exposure variable of interest was the median of the triplicate skin melanin measurements, in arbitrary units. The outcome of interest was presence of glaucoma.

RESULTS

Agreement between the triplicate inner arm melanin measurements was high, with an intraclass correlation of 0.99 (95% confidence interval, 0.98-0.99). Mean melanin values were 704 units (SD 94) in 76 cases and 694 units (SD 93) in 152 controls. Melanin was not statistically significantly associated with glaucoma after adjusting for sex and season of measurement (ie, dry vs. rainy), with an odds ratio of 1.15 (95% confidence interval, 0.59-2.24) per 100 units of inner arm melanin.

CONCLUSION

This study failed to find a significant association between skin pigmentation and glaucoma using an objective and reproducible assessment of pigmentation.

Smoking Is Associated with Higher Intraocular Pressure Regardless of Glaucoma: A Retrospective Study of 12.5 Million Patients Using the Intelligent Research in Sight (IRIS®) Registry

PURPOSE

To compare the average intraocular pressure (IOP) among smokers, past smokers, and never smokers using the American Academy of Ophthalmology Intelligent Research in Sight (IRIS®) Registry.

DESIGN

Retrospective database study of the IRIS® Registry data.

PARTICIPANTS

Intelligent Research in Sight Registry patients who were seen by an eye care provider during 2017.

METHODS

Patients were divided into current smoker, past smoker, and never smoker categories. The IOP was based on an average measurement, and separate analyses were performed in patients with and without a glaucoma diagnosis based on International Classification of Diseases (Ninth Edition and Tenth Edition) codes. Stratified, descriptive statistics by glaucoma status were determined, and the relationship between smoking and IOP was assessed with a multivariate linear regression model.

MAIN OUTCOME MEASURES

Mean IOP.

RESULTS

A total of 12 535 013 patients were included. Compared with never smokers, current and past smokers showed a statistically significantly higher IOP by 0.92 mmHg (95% confidence interval [CI], 0.88-0.95 mmHg) and 0.77 mmHg (95% CI, 0.75-0.79 mmHg), respectively, after adjusting for age, gender, glaucoma, age-related macular degeneration, diabetic retinopathy, cataract, glaucoma surgery, cataract surgery, and first-order interactions. In addition, the difference in IOP between current and never smokers was the highest in the fourth decade, regardless of the glaucoma status (glaucoma group, 1.14 mmHg [95% CI, 1.00-1.29 mmHg]; without glaucoma group, 0.68 mmHg [95% CI, 0.65-0.71 mmHg]).

CONCLUSIONS

Current smokers and past smokers have higher IOP than patients who never smoked. This difference is higher in patients with an underlying glaucoma diagnosis.

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.

Ocular blood flow as a clinical observation: Value, limitations and data analysis

Alterations in ocular blood flow have been identified as important risk factors for the onset and progression of numerous diseases of the eye. In particular, several population-based and longitudinal-based studies have provided compelling evidence of hemodynamic biomarkers as independent risk factors for ocular disease throughout several different geographic regions. Despite this evidence, the relative contribution of blood flow to ocular physiology and pathology in synergy with other risk factors and comorbidities (e.g., age, gender, race, diabetes and hypertension) remains uncertain. There is currently no gold standard for assessing all relevant vascular beds in the eye, and the heterogeneous vascular biomarkers derived from multiple ocular imaging technologies are non-interchangeable and difficult to interpret as a whole. As a result of these disease complexities and imaging limitations, standard statistical methods often yield inconsistent results across studies and are unable to quantify or explain a patient's overall risk for ocular disease. Combining mathematical modeling with artificial intelligence holds great promise for advancing data analysis in ophthalmology and enabling individualized risk assessment from diverse, multi-input clinical and demographic biomarkers. Mechanism-driven mathematical modeling makes virtual laboratories available to investigate pathogenic mechanisms, advance diagnostic ability and improve disease management. Artificial intelligence provides a novel method for utilizing a vast amount of data from a wide range of patient types to diagnose and monitor ocular disease. This article reviews the state of the art and major unanswered questions related to ocular vascular anatomy and physiology, ocular imaging techniques, clinical findings in glaucoma and other eye diseases, and mechanistic modeling predictions, while laying a path for integrating clinical observations with mathematical models and artificial intelligence. Viable alternatives for integrated data analysis are proposed that aim to overcome the limitations of standard statistical approaches and enable individually tailored precision medicine in ophthalmology.

Location of Retinal Nerve Fiber Layer Defects in Open-angle Glaucoma and Associated Factors

Purpose

To investigate the location of retinal nerve fiber layer defects (RNFLDs) in open-angle glaucoma and the differences in systemic and ocular factors between superotemporal and inferotemporal RNFLDs.

Methods

We performed a retrospective review of the 2008 to 2012 data from the Korea National Health and Nutrition Examination Survey. Subjects aged ≥19 years with an evaluable fundus photograph of at least one eye were enrolled, and open-angle glaucoma was diagnosed according to modified International Society of Geographical and Epidemiological Ophthalmology criteria. In subjects with open-angle glaucoma, locations of RNFLDs were evaluated, and systemic and ocular factors were compared between the bilateral superotemporal RNFLD group and bilateral inferotemporal RNFLD group.

Results

A total of 534 subjects had open-angle glaucoma with RNFLDs. The unilateral inferotemporal region (25.8%) was the most common location for RNFLDs, followed by the unilateral superotemporal region (24.4%). Multivariate analysis revealed that hypertension was more significantly associated (p = 0.048) with the bilateral superotemporal RNFLD group than with the bilateral inferotemporal RNFLD group.

Conclusions

Superotemporal RNFLDs are more related to hypertension than are inferotemporal RNFLDs.

Relationship between Alcohol Consumption and Ocular Pressure according to Facial Flushing in Korean Men with Obesity

Background

This study aimed to examine the relationship between alcohol consumption and intraocular pressure (IOP) according to facial flushing in Korean men with obesity.

Methods

The study included 479 Korean men with a body mass index of ≥25 kg/m² (75 non-drinkers, 174 with drinking-related facial flushing, and 230 without facial flushing) who underwent health check-ups between October 1, 2016 and March 31, 2017. Multivariate logistic regression was used to assess the relationship between alcohol consumption and high IOP (≥21 mm Hg).

Results

Flushers consuming ≤16 drinks per week had a significantly higher risk of high IOP than non-drinkers, depending on alcohol consumption (≤8 standard drinks: odds ratio [OR], 4.49; 95% confidence interval [CI], 1.05– 19.25; >8 but ≤16 standard drinks: OR, 8.14; 95% CI, 1.37–48.45). However, when the consumption was >16 drinks per week, the high IOP risk did not significantly increase (OR, 0.71; 95% CI, 0.05–10.69). In addition, there was no significant relationship between alcohol consumption and high IOP among non-flushers consuming ≤8 drinks per week (OR, 2.07; 95% CI, 0.52–8.19). However, a significantly increased risk of high IOP was observed among non-flushers consuming >8 drinks per week, depending on alcohol consumption (>8 but ≤16 standard drinks: OR, 4.84; 95% CI, 1.14–20.61; >16 standard drinks: OR, 4.08; 95% CI, 1.02–16.26).

Conclusion

This study suggests that obese men with alcohol flush reactions may have an increased risk of high IOP with the consumption of smaller amounts of alcohol than non-flushers.

Intraocular Pressure and Its Associations in a Russian Population: The Ural Eye and Medical Study

PURPOSE

To assess the normal distribution of intraocular pressure (IOP) and its associations with ocular, medical, and socioeconomic factors in a Russian population.

DESIGN

Population-based cross-sectional study.

METHODS

The Ural Eye and Medical Study conducted in a rural and urban area in Ufa/Bashkortostan included 5899 (80.5%) participants out of 7328 eligible individuals aged 40+ years. IOP was measured by noncontact tonometry.

RESULTS

After exclusion of individuals after glaucoma surgery or with antiglaucomatous therapy, mean IOP was 13.6 ± 3.8 mm Hg (median: 13 mm Hg; range: 3-49 mm Hg; 95% confidence interval [CI]: 8-23 mm Hg). The IOP range within the mean ± 2 standard deviations was 6.0-21.2 mm Hg. In multivariable analysis higher IOP was associated (regression coefficient r: 0.40) with the systemic parameters of female sex (nonstandardized regression coefficient B: 0.44; 95%CI: 0.22, 0.66; standardized regression coefficient beta: 0.06; P < .001), urban region of habitation (B: -0.27; 95% CI: 0.51, 0.03; beta: 0.03; P = .03), Russian ethnicity (B: 0.47; 95% CI: 0.20, 0.74; beta: 0.05; P = .001), higher body mass index (B: 0.06; 95% CI: 0.04, 0.08; beta: 0.08; P < .001), lower physical activity score (B: -0.02; 95% CI: -0.03, -0.002; beta: -0.03; P = .02), higher prevalence of diabetes mellitus (B: 0.42; 95% CI: 0.08, 0.76; beta: 0.03; P = .02), higher systolic blood pressure (B: 0.01; 95% CI: 0.01, 0.02; beta: 0.08; P < .001), fewer days with intake of fruits (B: -0.07; 95% CI: -0.12, -0.01; beta: 0.03; P = .01), lower blood concentration of bilirubin (B: -0.01; 95% CI: -0.02, -0.003; beta: -0.04; P = .008) and urea (B: -0.11; 95% CI: -0.17, -0.04; beta: -0.04; P = .003), worse best-corrected visual acuity (B: 0.64; 95% CI: 0.38, 0.90; beta: 0.13; P < .001), thicker central corneal thickness (B: 0.036; 95% CI: 0.033, 0.039; beta: 0.32; P < .001), higher anterior corneal refractive power (B: 0.11; 95% CI: 0.04, 0.18; beta: 0.05; P = .003), lower anterior chamber depth (B: -0.57; 95% CI: -0.83, -0.30; beta: -0.07; P < .001) (or lower prevalence of cataract surgery [B: -0.78; 95% CI: -1.44, -0.13; beta: -0.03; P = .02]), longer axial length (B: 0.30; 95% CI: 0.18, 0.42; beta: 0.07; P < .001), and higher prevalence of pseudoexfoliation (B: 1.08; 95% CI: 0.52, 1.63; beta: 1.01; P < .001). Measured IOP decreased by 0.36 mm Hg (95% CI: 0.33, 0.39) for each increase in central corneal thickness by 10 μm.

CONCLUSIONS

IOP was associated with a multitude of systemic and ocular parameters, the associations of which may be considered in defining the normal range of IOP.

Intraocular Pressure in General and Diabetic Populations From Southern China: the Dongguan Eye Study

Purpose

To investigate the distribution and risk factors for intraocular pressure (IOP) among general and diabetic populations in Southern China.

Methods

The study participants aged 40 years or older were enrolled from the Dongguan Eye Study, a population-based cross-sectional study from September 2011 to February 2012. Systemic and ophthalmic examinations were performed, and diabetes status was screened based on the American Diabetes Association diagnostic criteria (2010). IOP was measured by a noncontact tonometer per standardized protocol. Regression analyses were used to assess the association between potential risk factors and IOP.

Results

A total of 2112 subjects were included with a median age of 55 years. IOP for general population showed a near normal distribution with an average of 15.58 ± 3.27 mm Hg. Multiple regression analyses revealed that higher IOP was significantly correlated with younger age, higher body mass index (BMI), shorter height, higher blood pressure (BP), higher fasting blood glucose (FBG), higher low-density lipoprotein cholesterol (LDL-C), lower high-density lipoprotein cholesterol (HDL-C), and thicker central corneal thickness (CCT). There was no association between diabetes status and IOP after adjusting for possible confounders. IOP for diabetic participants showed a right-skewed distribution. Risk factors for IOP elevation in diabetes included female, younger age, higher BP, higher LDL-C, lower HDL-C, and thicker CCT.

Conclusions

The present study identifies risk factors for elevated IOP in general and diabetic populations. Younger age and lower HDL-C, as well as higher BP, LDL-C, and CCT were significant factors contributing to higher IOP, especially in the female diabetic population.

Functional MRI reveals effects of high intraocular pressure on central nervous system in high-tension glaucoma patients

PURPOSE

To evaluate the effects of high intraocular pressure (IOP) on central nervous system in patients with high-tension glaucoma (HTG) by using resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

Thirty-six patients with HTG and twenty age- and gender-matched healthy controls (HCs) were recruited and underwent IOP measurement and rs-fMRI scan. The whole brain regional homogeneity (ReHo) value was calculated among the enrolled subjects. Two-sample t tests with permutation test and threshold-free cluster enhancement was performed between HTG group and HCs. Correlation analyses between IOP and ReHo values were conducted.

RESULTS

Compared with HCs, HTG group showed increased ReHo values in the left lobule 8 of cerebellar hemisphere, left lobule 4 and 5 of cerebellar hemisphere and left fusiform gyrus (FG) (p < 0.05). HTG group showed decreased ReHo value in the left middle frontal gyrus (MFG) (p < 0.05). Intraocular pressure of the left eye in HTG group experienced a significant positive correlation with ReHo value of the left FG (r = 0.370, p = 0.026), IOP of the right eye in HTG group showed a significant negative correlation with ReHo value in the left MFG (r = -0.421, p = 0.011).

CONCLUSION

Resting-state fMRI ReHo analyses associated elevated IOP with abnormal regional activity in several brain regions related to higher visual function and visual memory consolidation. High-tension glaucoma patients also showed diminished integration of visual information and cerebellar function. These results may provide imaging support for pathophysiological research of HTG and may reveal new targets for the accurate treatment of HTG.

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.