Associations with intraocular pressure in Latinos: the Los Angeles Latino Eye Study

Seasonal variations in anterior segment angle parameters in myopes and emmetropes

CLINICAL RELEVANCE

Seasonal variations are known to occur in a range of ocular parameters and in conditions including refractive error and glaucoma. It is of clinical importance to know if seasonal changes also occur in anterior segment angle parameters, given that they can influence these conditions.

BACKGROUND

The study aimed to examine the seasonal variations in anterior segment angle parameters in healthy young adults.

METHODS

Twenty-three emmetropic participants with a mean age of 26.17 ± 4.43 years and 22 myopic participants with a mean age of 27.27 ± 4.47 years completed four seasons of data collection. Anterior segment angle parameters were measured using swept-source anterior segment optical coherence tomography. Intraocular pressure (IOP) and objective refraction were also measured. Repeated-measures analysis of variance was used to determine the effect of season and refractive error on the various ocular parameters.

RESULTS

A significant main effect of season was found for the majority of anterior segment angle parameters, including the angle opening distance at 500 and 750 µm from the scleral spur (p = 0.02, p = 0.006, respectively), angle recess area at 500 and 750 µm from the scleral spur (both p = 0.002), and trabecular iris space area at 500 and 750 µm from the scleral (p = 0.02, p = 0.008, respectively). However, measures of anterior chamber depth and trabecular iris angle did not exhibit statistically significant seasonal variations (all p > 0.05). A significant main effect of season was also found for the changes in IOP (p = 0.004) and objective refraction (p < 0.001). There was no season by refractive group interaction for any anterior segment angle parameter or IOP (all p > 0.05).

CONCLUSION

There is a small but significant seasonal changes in the anterior segment angle parameters, refractive error, and IOP in healthy young adult males, in which the anterior segment angle dimensions are narrower, the IOP is higher, and the refraction is more myopic during winter.

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.

Intraocular pressure and its determinants in a very old population. The ural very old study

Purpose

To explore intraocular pressure (IOP) and its associated parameters in an aged population.

Methods

The epidemiologic Ural Very Old Study (UVOS) conducted in Bashkortostan/Russia included 1526 participants with an age of ≥85 years. Besides a whole series of ocular and systemic examinations, IOP was determined applying non-contact tonometry. Body mass index, diastolic blood pressure and age were the factors used to estimate the cerebrospinal fluid pressure (CSFP).

Results

The study consisted of 904 participants (age: 88.6 ± 2.7 years) with available IOP readings and without anti-glaucomatous therapy. Mean IOP was 14.5 ± 5.1 mmHg (median: 14 mm Hg; Q1:11; Q3:16; 95%CI:8,25) and 14.8 ± 4.6 mmHg (median: 14 mm Hg; Q1:12; Q3:17; 95%CI:8,28) in the right and left eyes, respectively. Higher IOP correlated (multivariable analysis; correlation coefficient r2:0.32) with female sex (P < 0.001), more sedentary lifestyle (P = 0.006), higher estimated CSFP (P < 0.001), higher total protein serum concentration (P < 0.001), stronger hand grip force (P = 0.01), thicker central cornea (P < 0.001), longer axial length (P = 0.01), absence of previous cataract surgery (P = 0.001), higher degree of pseudoexfoliation (P = 0.02, and thinner peripapillary retinal nerve fiber layer thickness (P = 0.004). Using this that model, IOP reading enlarged by 0.22 mmHg (95% CI: 0.09, 0.35) for each increase in estimated CSFP by 1 mm Hg, by 0.03 mm Hg (95% CI: 0.02,0.05) for each thickening in central corneal thickness by 1 μm, by 0.56 mm Hg (95%CI: 0.13,1.00) for each axial elongation by 1 mm, and by 0.40 mmHg (95% CI: 0.06,0.74) for each increase in the degree of pseudoexfoliation, and it decreased by 0.40 mmHg (95% CI: 0.06,0.74) by cataract surgery.

Conclusions

In this study population aged 85+years, IOP readings showed similar relationships as in younger study populations, including positive associations with higher estimated CSFP and longer axial length and a negative association with cataract surgery.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

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.

Risk factors associated with elevated intraocular pressure: a population-based study in a rural community of Bangladesh

OBJECTIVE

High intraocular pressure (IOP) is one of the major modifiable risk factors for glaucoma. The objective was to examine socio-demographic and clinical factors related to IOP.

METHODS AND ANALYSIS

This study was conducted among 3097 adults residing in a rural area of Bangladesh, with all participants undergoing clinical and ophthalmological evaluations. The measurement of IOP was carried out using of a rebound Tonometer called Icare pro. Multiple logistic regression analysis was employed to identify variables associated to IOP levels of 21 mm Hg or above. Adjusted OR (aOR) and 95% CI were reported.

RESULTS

This study found that, in total, 9% of the study population had high IOP in one or both eyes. Elevated IOP was significantly associated with respondents who were service holders (aOR 2.52; 95% CI 1.48 to 4.31), had a lower education level (aOR 1.55, 95% CI 1.07 to 2.23), used biomass fuel (aOR 2.00; 95% CI 1.09 to 3.67), belonged to a higher socioeconomic position (aOR 1.55, 95% CI 1.07 to 2.23) and had obesity (aOR 2.00; 95% CI 1.07 to 3.73), hypertension (aOR 1.32; 95% CI 1.01 to 1.73) or history of diabetes (aOR 2.44; 95% CI 1.67 to 3.55), after adjusting for covariates including age, sex, marital status, light source and tobacco consumption, in a multiple regression analysis.

CONCLUSION

Chronic diseases, such as hypertension and diabetes, obesity and sociodemographic characteristics such as high socioeconomic status and use of biomass fuels, have all been linked to elevated IOP. Patients with chronic diseases should undergo for IOP testing regularly.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Translational Relevance

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

Long-term effects of obstructive sleep apnea and its treatment on open-angle glaucoma: a big-data cohort study

STUDY OBJECTIVES

The relationship between open-angle glaucoma (OAG) and obstructive sleep apnea (OSA) is unclear. The long-term risk for OAG after OSA diagnosis has not been investigated. Therefore, we assessed the risk for OAG among patients with OSA over a 12-year follow-up period using nationwide, population-based data.

METHODS

The OSA group was randomly selected from among 3.5 million individuals registered with the National Health Insurance Service. The non-OSA group was obtained through propensity score matching considering several variables. The primary endpoint was glaucoma diagnosis.

RESULTS

The OSA and non-OSA groups both included 6,369 individuals. The overall hazard ratio for OAG in the OSA group was 1.42 (95% confidence interval [CI]: 1.19-1.69). In subgroup analysis, the hazard ratio for OAG was 1.94 (95% CI: 1.57-2.41) for those aged > 60 years, 1.50 (95% CI: 1.20-1.89) for those with diabetes mellitus, 1.53 (95% CI: 1.26-1.86) for those with hypertension, and 0.71 (95% CI: 0.52-0.96) for those with a history of OSA surgery.

CONCLUSIONS

Over the 12-year follow-up, the risk for OAG increased after OSA diagnosis. Further research will be necessary to determine if treating OSA can mitigate this association.

CITATION

Lee T-E, Kim JS, Yeom SW, Lee MG, Lee JH, Lee H-J. Long-term effects of obstructive sleep apnea and its treatment on open-angle glaucoma: a big-data cohort study. J Clin Sleep Med. 2023;19(2):339-346.

Age-specific distribution of intraocular pressure in elderly Iranian population and its associated factors

Background

The purpose of this study was to determine the distribution of intraocular pressure (IOP) and assess its association with age, sex, systemic blood pressure, diabetes mellitus, body mass index (BMI) and tobacco smoking in Iranian elderly population.

Methods

This cohort-based, cross-sectional study assessed elderly individuals aged 60-90 years in Amirkola, northern Iran, in 2016-2017. Past medical history, blood pressure, diabetes mellitus, BMI and tobacco smoking were recorded through an interview and physical examination. IOP was assessed using non-contact tonometry.

Results

Total of 1377 individuals participated in this study, out of which 1346 IOP measurements were included for the final analysis. The mean age of participants was 69.4 ± 7.1 years and mean IOP was determined to be 16.7 ± 3.2 mmHg. Majority of the participants were males (56.1% vs 43.1%), 73.8% of participants were overweight or obese, 6.1% smoked tobacco, 28.9% had diabetes mellitus and 84.9% had higher than normal blood pressure. Through multiple regression analysis, it was determined that age (β=-0.132, p<0.001) was negatively associated with IOP, and the presence of diabetes mellitus (β=0.118, p<0.001), systolic blood pressure (β=0.101, p<0.001), and BMI (β=0.020, P=0.020) were positively associated with IOP.

Conclusion

Mean IOP of individuals in this study was higher than average based on other studies. Age, was negatively and systemic blood pressure, BMI and presence of diabetes mellitus were positively associated with mean IOP of elderly Iranian population. Sex and tobacco smoking were not correlated with IOP.

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.

Optic Disc Drusen in Patients With Ocular Hypertension: A Case Series and Review of the Literature

BACKGROUND

The identification of glaucomatous optic neuropathy in the setting of optic disc drusen (ODD) is a challenge, and the decision of whether to offer treatment in the form of intraocular pressure (IOP) reduction is controversial. Here, we present a series of patients with coexisting ocular hypertension and ODD to evaluate clinical features, treatment options, and progression of optic neuropathy. In addition, a review of the literature on ODD with elevated IOP is provided.

METHODS

Six patients with ODD and a history of ocular hypertension are presented. Components of the examination and imaging modalities used to establish the diagnosis of ODD were recorded and a description of ocular hypertension history, glaucoma testing, and the potential treatment of IOP were also provided.

RESULTS

In this series, 4 of 6 patients with concurrent ocular hypertension and ODD showed progression of optic neuropathy as assessed by visual field or retinal nerve fiber layer thickness. Of the 2 patients who did not show evidence of progression, 1 was treated with IOP-lowering medications and 1 was observed off treatment. Of the 4 patients who showed evidence of progression, all 4 were initially treated with IOP-lowering medications and 2 ultimately went on to have trabeculectomy surgery. In the patients with progressive optic neuropathy, lowering the IOP seemed to halt the progression suggesting there was a pressure-sensitive component.

CONCLUSIONS

Distinguishing changes to the optic nerve, particularly the structural changes at the lamina cribrosa of true glaucomatous optic neuropathy in the setting of ODD, is a challenge. Careful consideration of risk factors including age, presenting features, progression indicators, and management goals is to be accounted for in the decision to offer treatment. We see the presence ODD in the patients with ocular hypertension as an additional risk for progressive changes to the nerve fiber layer and visual field that needs to be considered when determining whether to initiate therapy. Our data suggest that treatment of IOP in the patients with ocular hypertension with ODD and evidence of progression reduces the risk of further progression. Further work is needed to determine whether progression of optic neuropathy in the setting of coexisting ODD and ocular hypertension is related mechanistically to predominantly an ODD-type process, a glaucomatous process, or a combination thereof.

The Association Between Age and Systemic Variables and the Longitudinal Trend of Intraocular Pressure in a Large-Scale Health Examination Cohort

Purpose

The detailed effects of age and systemic factors on intraocular pressure (IOP) have not been fully understood because of the lack of a large-scale longitudinal investigation. This study aimed to investigate the effect of various systemic factors on the longitudinal change of IOP.

Methods

There were a total of 20,909 eyes of 10,471 subjects from a health checkup cohort that were followed up for systemic factors: (i) age at baseline, (ii) sex, (iii) time series body mass index (BMI), (iv) time series smoking habits, (v) time series systolic and diastolic blood pressures (SBP and DBP), and (vi) time series 19 blood examinations (all of the time series data was acquired at each annual visit), along with IOP annually for at least 8 years. Then the longitudinal effect of the systemic factors on the change of IOP was investigated.

Results

IOP significantly decreased by −0.084 mm Hg/year. BMI, SBP, DBP, smoking habits, total triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and glycosylated hemoglobin A1c were not significantly associated with the change of IOP. Higher values of age, aspartate aminotransferase, hemoglobin, platelet, and calcium were suggested to be significantly associated with the decrease of IOP, whereas higher alanine aminotransferase, guanosine triphosphate, white blood cell count, red blood cell count, and female gender were significantly associated with the increase of IOP.

Conclusions

Age, aspartate aminotransferase, hemoglobin, platelet, calcium, alanine aminotransferase, guanosine triphosphate, white blood cell count, red blood cell count, and gender were the systemic variables significantly associated with the change of IOP.

Relationship between blood pressure and intraocular pressure in the JPHC-NEXT eye study

Although a positive link between hypertension and intraocular pressure (IOP) has been suggested, the individual effects of systolic and diastolic blood pressure (SBP and DBP, respectively) on IOP remain unclear, particularly among Japanese populations. Here, we conducted a large-scale, cross-sectional study to determine individual and combined effects of SBP/DBP and hypertension on IOP. In total, 6783 Japanese people aged over 40 years underwent systemic and ophthalmological examinations, including measurements of blood pressure and IOP, conducted using non-contact tonometers. After adjusting for a priori known confounding factors, SBP and DBP levels were found to be positively correlated with IOP levels. The multivariable-adjusted odds ratio when comparing the hypertensive and normotensive groups for the prevalence of ocular hypertension was 1.88 (95% confidence interval, 1.14-3.08). When analysing the combined effects of SBP and DBP on ocular hypertension, SBP elevation had a greater effect on ocular hypertension than DBP increase. In conclusion, SBP and DBP levels and the prevalence of systemic hypertension were found to be positively associated with IOP levels and the prevalence of ocular hypertension in an ophthalmologically healthy Japanese population. Our findings suggest that systemic blood pressure control may be key for controlling IOP.

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.

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.

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.

Lowering Intraocular Pressure: A Potential Approach for Controlling High Myopia Progression

High myopia is among the most common causes of vision impairment, and it is mainly characterized by abnormal elongation of the axial length, leading to pathologic changes in the ocular structures. Owing to the close relationship between high myopia and glaucoma, the association between intraocular pressure (IOP) and high myopia progression has garnered attention. However, whether lowering IOP can retard the progression of high myopia is unclear. On reviewing previous studies, we suggest that lowering IOP plays a role in progressive axial length elongation in high myopia, particularly in pathologic myopia, wherein the sclera is more remodeled. Based on the responses of the ocular layers, we further proposed the potential mechanisms. For the sclera, lowering the IOP could inhibit the activation of scleral fibroblasts and then reduce scleral remodeling, and a decrease in the scleral distending force would retard the ocular expansion like a balloon. For the choroid, lowering IOP results in an increase in choroidal blood perfusion, thereby reducing scleral hypoxia and slowing down scleral remodeling. The final effect of these pathways is slowing axial elongation and the development of scleral staphyloma. Further animal and clinical studies regarding high myopia with varied degree of IOP and the changes of choroid and sclera during IOP fluctuation in high myopia are needed to verify the role of IOP in the pathogenesis and progression of high myopia. It is hoped that this may lead to the development of a prospective treatment option to prevent and control high myopia progression.

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.

Time-of-Year Variation in Intraocular Pressure

PRÉCIS

In this study conducted in Chicago, IL, intraocular pressure (IOP) level was found to have a subtle, but measurable, annual pattern. Reasonable evidence is presented for a time-of-year variation in IOP. Adequate numbers of subjects must be studied to detect this small variation.

PURPOSE

The aim was to investigate the relationship between IOP and time of year.

METHODS

During a separate investigation, patients from 2011 to 2018 (dataset A, N=3041) in an urban, academic facility in Chicago, IL received an examination that included Goldmann applanation tonometry. Regression analyses assessed the relationship between time of year and IOP. Two additional datasets, 1 collected in a similar manner during 1999 and 2002 (dataset B, N=3261) and another consisting of all first visits during 2012 and 2017 (dataset C, N=69,858), were used to confirm and further investigate trends.

RESULTS

For dataset A, peak mean IOP occurred in December/January (15.7±3.7/15.7±3.8 mm Hg) and lowest in September (14.5±3.1 mm Hg). The analysis suggested conventional quarterly analysis (January to March, etc.) can conceal time-of-year relationships because of inadequate statistical power and timing of IOP variation. Multiple linear regression analysis, with a November-to-October reordering, detected an annual, downward IOP trend (P<0.0001). Analysis of dataset B confirmed this trend (P<0.001). Fourier analysis on datasets A and B combined supported a 12-month IOP cycle for right/left eyes (P=0.01/P=0.005) and dataset C provided stronger evidence for an annual periodicity (P<0.0001). Harmonics analysis of dataset C showed a repeating pattern where IOP trended downward around April, and then back upward around October.

CONCLUSIONS

This analysis strongly supports a demonstrable annual, cyclical IOP pattern with a trough to peak variation of ≈1 mm Hg, which has a seasonal relationship.

The Effects of Sex, Oral Contraception, and Menstrual Cycle Phase on Intraocular Pressure, Central Corneal Thickness, and Foveal Thickness: A Descriptive Analysis

The primary goal of this study was to investigate the effects of sex, oral contraceptive (OC) use, and menstrual cycle phase on common ocular parameters assessed during ophthalmic evaluations, namely intraocular pressure (IOP), central corneal thickness (CCT), and foveal thickness (FT), in young healthy adults. We measured IOP, CCT, and FT in 60 participants (16 men, 16 contraceptive users, and 28 cycling women) over two sessions that characterized the menstrual cycle phase in women. For men in our study, two sessions were separated by two weeks. For women, the two sessions were scheduled during the follicular and luteal phases of the menstrual cycle. There was a trend towards higher IOP in men, and the difference was significant for white, non-Hispanic subjects and for white subjects considered separately. There was also a trend for thicker corneas in women, but men had significantly thicker foveae. CCT and FT were not different between men and OC-users, hinting at a moderating hormonal effect of oral contraceptive use. We found that IOP, CCT, and FT were equivalent between the follicular and luteal phases, which may be owing to the timing of our sessions. However, our findings strongly suggest that clinicians should consider contraceptive use during routine ophthalmic evaluations, as it could inform glaucomatous risk in women.

Axial length and its associations in the Ural Very Old Study

To assess the distribution of axial length as surrogate for myopia and its determinants in an old population, we performed the Ural Very Old Study as a population-based cohort study. Out of 1882 eligible individuals aged 85 + years, the Ural Very Old Study performed in an urban and rural region in Bashkortostan/Russia included 1526 (81.1%) individuals undergoing ophthalmological and medical examinations with sonographic axial length measurement. Biometric data were available for 717 (47.0%) individuals with a mean age of 88.0 ± 2.6 years (range 85–98 years; 25%). Mean axial length was 23.1 ± 1.1 mm (range 19.37–28.89 mm). Prevalences of moderate myopia (axial length 24.5–< 26.5 mm) and high myopia (axial length ≥ 26.5 mm) were 47/717 (6.6%; 95% CI 4.7, 8.4) and 10/717 (1.4%; 95% CI 0.5, 2.3), respectively. In multivariable analysis, longer axial length was associated (coefficient of determination r² 0.25) with taller body height (standardized regression coefficient beta:0.16;non-standardized regression coefficient B: 0.02; 95% confidence interval (CI) 0.01, 0.03; P < 0.001), higher level of education (beta: 0.12; B: 0.07; 95% CI 0.02, 0.11; P = 0.002), and lower corneal refractive power (beta: − 0.35; B: − 0.23; 95% CI − 0.28, − 0.18; P < 0.001). Higher prevalence of moderate myopia, however not of high myopia, was associated with higher educational level (OR 1.39; 95% CI 1.09, 1.68; P = 0.007) and lower corneal refractive power (OR 0.77; 95% CI 0.63, 0.94; P = 0.01). In this old study population, prevalence of moderate axial myopia (6.6% versus 9.7%) was lower than, and prevalence of high axial myopia (1.4% versus 1.4%) was similar as, in a corresponding study on a younger population from the same Russian region. Both myopia prevalence rates were higher than in rural Central India (1.5% and 0.4%, respectively). As in other, younger, populations, axial length and moderate myopia prevalence increased with higher educational level, while high myopia prevalence was independent of the educational level.

Longer Axial Length Potentiates Relationship of Intraocular Pressure and Peripapillary Vessel Density in Glaucoma Patients

Purpose

The purpose of this study was to investigate how axial length (AL) changes the relationship of intraocular pressure (IOP) with peripapillary vessel density (pVD) in glaucoma versus non-glaucomatous eyes.

Methods

A population-based, cross-sectional study of 2127 African Americans aged 40 years and older in Inglewood, California, were imaged with 6 × 6-mm optic disc optical coherence tomography angiography scans. There were 1028 healthy subjects (1539 eyes) and 65 subjects with glaucoma (86 eyes) who met inclusion criteria. A multivariable linear mixed effects regression model investigated the relationship of IOP on pVD after controlling for signal strength, retinal nerve fiber layer thickness, and age. These results were stratified by AL groups.

Results

Higher IOP was a significant predictor of lower pVD among subjects with glaucoma (P = 0.009), but not among healthy subjects (P = 0.26). After stratifying by the sample median AL (23.46 mm), higher IOP was associated with lower pVD among subjects with glaucoma with longer AL (≥ 23.46 mm, P = 0.005), but not among those in the shorter AL (< 23.46 mm, P = 0.45). IOP was not significantly associated with pVD among healthy subjects in either AL stratum.

Conclusions

Among subjects with glaucoma with longer AL, IOP was significantly associated with pVD. This relationship was not seen among subjects with glaucoma with shorter AL or non-glaucomatous subjects in either AL group. These findings support the hypothesis that disturbed retinal autoregulation may be present in subjects with glaucoma with longer AL. Longitudinal studies are needed to further investigate whether axial elongation increases glaucoma risk by compromising retinal autoregulation.

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.

Distribution of IOP and its relationship with refractive error and other factors: the Anyang University Students Eye Study

AIM

To investigate the distribution of intraocular pressure (IOP) and its relationship with refractive error and other factors in university students from Anyang, China.

METHODS

A university-based study was conducted. Subjects were invited to complete ophthalmic examinations, including visual acuity, noncontact tonometry (NCT), cycloplegic autorefraction, and ocular biometry. Univariable and multivariable analyses were used to evaluate the associations between IOP and other factors. Only data from right eyes were used in analysis.

RESULTS

A total of 7720 subjects aged 16 to 26 years old were included, and 2834 (36.4%) of the participants were male. The mean IOP of the right eye for all subjects was 15.52±3.20 mm Hg (95%CI: 15.45, 15.59). Using multivariate linear regression analysis, IOP was found to correlate significantly with younger age (P<0.001; standardized regression coefficient β, -0.061; regression coefficient β, -0.139; 95%CI: -0.18, -0.09), higher myopic refractive error (P=0.044; standardized β, -0.060; regression coefficient β, -0.770; 95%CI: -0.15, -0.002), higher central corneal thickness (P<0.001; standardized β, 0.450; regression coefficient β, 0.044; 95%CI: 0.04, 0.05), and shorter axial length (AL; P<0.001; standardized β, -0.061; regression coefficient β, -0.163; 95%CI: -0.25, -0.07).

CONCLUSION

This study described the normal distribution of IOP. In Chinese university students aged 16-26y, higher IOP is associated with younger age, higher myopic refractive error, higher thickness of the central cornea, and shorter AL.

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.

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.

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.

Intraocular pressure predicts premature coronary atherosclerosis

OBJECTIVE

The aim of this study was to investigate the association between intraocular pressure (IOP) and premature atherosclerotic coronary artery disease (PACAD) by comparing central corneal thicknesses (CCTs) measurements.

METHODS

One hundred-eighty-six subjects were enrolled in this cross-sectional study, 100 in the PACAD group and 86 in the control group. All participants underwent a physical examination and routine biochemical tests. Ophthalmological examinations, including IOP and CCTs measurements, were performed for each subject. Additionally, pulse wave velocity measurements were obtained and recorded.

RESULTS

Participants with PACAD showed significantly higher IOP values than those without atherosclerosis (p = 0.001), and there was no statistically significant difference between the groups in terms of CCT (p = 0.343). Also, pulse wave velocity (PWV) values were statistically significantly higher in the PACAD group (p = 0.001). High IOP was not significantly associated with metabolic syndrome parameters (p > 0.05).

CONCLUSIONS

A relationship was found between PACAD and IOP, but CCTs were not associated with PACAD. The IOP measurement is affected by CCT; therefore, CCT is used to correct IOP values. To our knowledge, this is the first study to report a positive relationship between PACAD and IOP based on CCTs measurements.

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.

Significant intraocular pressure associated with open-angle glaucoma: Korea National Health and Nutrition Examination Survey 2010-2011

Objectives

To investigate significant intraocular pressure (IOP) levels associated with the risk of open-angle glaucoma (OAG) in the treatment-naïve Korean population.

Methods

Participants ≥20 years of age in Korea National Health and Nutrition Examination Survey 2010–2011 were divided into two groups, those with higher and lower IOP values, compared with the reference IOP value. We compared the risk of OAG in each group using regression analyses. The IOP value that yielded the highest statistical significance was determined as an IOP significantly associated with the OAG risk.

Results

A total of 7,650 participants (7,292 control, 358 OAG) were included. The mean IOP was significantly higher in OAG group (14.4 ± 2.9 mmHg), compared to control group (13.9 ± 2.7 mmHg, P = 0.022). In association with an increased risk of OAG, the significant IOP value was 18 mmHg (Odds ratio [OR] = 1.79, 95% confidence interval [CI] 1.14–2.80, P = 0.011). Additionally, sex-difference was identified and they were 19 mmHg (OR = 2.79, 95% CI 1.27–6.16, P = 0.011) in men and 18 mmHg (OR = 2.65, 95% CI 1.32–5.33, P = 0.006) in women. The IOP values associated with significantly decreased risk of glaucoma were determined to be 14 mmHg in men (OR = 0.68, 95% CI 0.47–0.99, P = 0.042) and 16 mmHg in women (OR = 0.47, 95% CI 0.27–0.81, P = 0.007).

Conclusions

In consideration of the risk to benefit ratio, the reference IOP level for screening or setting the target IOP for treatment could be considered different from traditional 21 mmHg in Korean population.

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.

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.

Transitions of the Understanding and Definition of Primary Glaucoma

Objective:

In previous decades, glaucoma has been primarily attributed to elevated intraocular pressure (IOP), but this has gradually been replaced by the development of optic neuropathy as the central concept of glaucoma in developed countries. However, there still remain strong controversies in the definition of glaucoma in China. In this current review, we are going to discuss these controversies and elaborate on the historical transitions of the definition of glaucoma both in China and developed countries. Furthermore, we will briefly describe the “ocular-cranial pressure gradient” theory and discuss the relationship between glaucoma and degenerative diseases of the central nervous system (CNS) in order to show the complex pathogenesis of glaucoma and the importance for the modification to the definition of glaucoma.

Data Sources:

We performed a comprehensive search in both PubMed and SinoMed using the following keywords: (a) “primary glaucoma” and “guideline,” (b) “ocular-cranial pressure gradient,” and (c) “glaucoma,” “Alzheimer's disease,” and “Parkinson's disease.” The literature search included the related articles with no restrictions on publication date.

Study Selection:

The primary references were Chinese and English articles including (a) original guidelines and expert consensuses of primary glaucoma, (b) reviews focusing on the differences between various versions of these guidelines and consensuses, and (c) papers about ocular-cranial pressure gradient theory and the relationship between glaucoma and CNS degenerative diseases.

Results:

The definitions and classifications of both primary open-angle glaucoma and primary angle-closure glaucoma differ between Chinese glaucoma consensuses and international primary glaucoma guidelines. Chinese definitions and classifications put more emphasis on the IOP, while international guidelines put more emphasis on the presence of optic neuropathy. The ocular-cranial pressure gradient theory and the research on the relationship between glaucoma and CNS degenerative diseases have provided new directions for exploring the pathogenesis of glaucoma.

Conclusions:

As regards the definition and classification of primary glaucoma, we find that there are still some discrepancies between Chinese expert consensuses and international guidelines. Glaucoma is a disease with complex etiologies, while its common characteristic is a specific optic neuropathy. The current definition and understanding of glaucoma is an ongoing and evolving process, reflecting our latest available evidence on its pathogenesis. Chinese ophthalmology community may need to update our guidelines, accommodating these latest developments.

Genome-wide association analyses identify new loci influencing intraocular pressure

Elevated intraocular pressure (IOP) is a significant risk factor for glaucoma, the leading cause of irreversible blindness worldwide. While previous studies have identified numerous genetic variants associated with IOP, these loci only explain a fraction of IOP heritability. Recently established of biobank repositories have resulted in large amounts of data, enabling the identification of the remaining heritability for complex traits. Here, we describe the largest genome-wide association study of IOP to date using participants of European ancestry from the UK Biobank. We identified 671 directly genotyped variants that are significantly associated with IOP (P < 5 × 10-8). In addition to 103 novel loci, the top ranked novel IOP genes are LMX1B, NR1H3, MADD and SEPT9. We replicated these findings in an external population and examined the pleiotropic nature of these loci. These discoveries not only further our understanding of the genetic architecture of IOP, but also shed new light on the biological processes underlying glaucoma.

Axial length and its associations in a Russian population: The Ural Eye and Medical Study

Purpose

To assess the normal distribution of axial length and its associations in a population of Russia.

Methods

The population-based Ural Eye and Medical Study included 5,899 (80.5%) individuals out of 7328 eligible individuals aged 40+ years. The participants underwent an ocular and systemic examination. Axial length was measured sonographically (Ultra-compact A/B/P ultrasound system, Quantel Medical, Cournon d'Auvergne, France).

Results

Biometric data were available for 5707 (96.7%) individuals with a mean age of 58.8±10.6 years (range:40–94 years; 25%, 50%, 75% quartile: 51.0, 58.0, 66.0 years, respectively). Mean axial length was 23.30±1.10 mm (range: 19.02–32.87mm; 95% confidence interval (CI): 21.36–25.89; 25%, 50%, 75% quartile: 22.65mm, 23.23mm, 23.88mm, resp.). Prevalences of moderate myopia (axial length:24.5-<26.5mm) and high myopia (axial length >26.5mm) were 555/5707 (8.7%;95%CI:9.0,10.5) and 78/5707 (1.4%;95%CI:1.1,1.7), respectively. Longer axial length (mean:23.30±1.10mm) was associated (correlation coefficient r²:0.70) with older age (P<0.001;standardized regression coefficient beta:0.14), taller body height (P<0.001;beta:0.07), higher level of education (P<0.001;beta:0.04), higher intraocular pressure (P<0.001;beta:0.03), more myopic spherical refractive error (P<0.001;beta:-0.55), lower corneal refractive power (P<0.001;beta:-0.44), deeper anterior chamber depth (P<0.001;beta:0.20), wider anterior chamber angle (P<0.001;beta:0.05), thinner peripapillary retinal nerve fiber layer thickness (P<0.001;beta:-0.04), higher degree of macular fundus tessellation (P<0.001;beta:0.08), lower prevalence of epiretinal membranes (P = 0.01;beta-0.02) and pseudoexfoliation (P = 0.007;beta:-0.02) and higher prevalence of myopic maculopathy (P<0.001;beta:0.08). In that model, prevalence of age-related macular degeneration (any type: P = 0.84; early type: P = 0.46), diabetic retinopathy (P = 0.16), and region of habitation (P = 0.27) were not significantly associated with axial length.

Conclusions

Mean axial length in this typically multi-ethnic Russian study population was comparable with values from populations in Singapore and Beijing. In contrast to previous studies, axial length was not significantly related with the prevalences of age-related macular degeneration and diabetic retinopathy or region of habitation.

Blood pressure, ocular perfusion pressure and open-angle glaucoma in patients with systemic hypertension

Background

The aim of the study was to evaluate the relationship between blood pressure (BP), ocular perfusion pressure (OPP) and occurrence of primary open-angle glaucoma (POAG) among patients with systemic hypertension.

Participants and methods

A cross-sectional study of hypertensive patients was conducted in six cities in Colombia. The participants underwent a complete ophthalmological examination. The intraocular pressure measurement was obtained by Goldmann tonometry. The diagnosis of glaucoma was confirmed by visual field and optic nerve photos. Interviews and questionnaires were used to evaluate participants’ lifestyle and other health conditions. A multinomial logistic regression was used to assess the relationship between BP, OPP and presence of suspected or confirmed POAG.

Results

A total of 1,272 individuals were included in this study; 131 (10.3%) were diagnosed with suspected glaucoma and 65 (5.1%) with confirmed glaucoma. High values of diastolic BP (>90 mmHg) and low values of OPP (<40 mmHg) were associated to an increased risk of confirmed POAG. The type of antihypertensive treatment did not modify these relationships.

Conclusion

This study suggests that there is a close relationship between OPP and confirmed glaucoma in hypertensive patients, providing further evidence of the vascular mechanism in glaucoma pathogenesis.

Intraocular pressure and its normal range adjusted for ocular and systemic parameters. The Beijing Eye Study 2011

Purpose

To examine the distribution of intraocular pressure (IOP) in a normal population and the associations of IOP with other ocular and systemic parameters.

Methods

Out of 3468 participants of the population-based cross-sectional Beijing Eye Study 2011 we selected those individuals without glaucomatous optic neuropathy. The study particpants underwent a detailed ophthalmologic and systemic examination. IOP was measured by air puff non-contact tonometry.

Results

The study included 3135 eyes of 3135 participants with a mean age of 64.1 ± 9.6 years (mean ± standard deviation). The mean IOP was 14.7 ± 2.8 mmHg. The 95% percentile and 97.5% percentile of the IOP distribution decreased from 20 mmHg / 21 mmHg in individuals aged 40 to 54 years to 18 mmHg / 19 mmHg in individuals aged ≥80 years. In multivariable analysis, higher IOP was associated with the systemic parameters of younger age (P<0.001), higher blood concentration of glucose (P = 0.03) and triglycerides (P<0.001), higher diastolic blood pressure (P<0.001), higher pulse rate (P = 0.003) and higher quantity of alcohol consumption (P = 0.004), and with the ocular parameters of larger central corneal thickness (P<0.001), more myopic refractive error (P = 0.01) and steeper anterior corneal curvature radius (P = 0.006). IOP decreased significantly by 0.50 mmHg and 0.76 mmHg for each increase in age by 10 years and each increase in corneal curvature radius by 1.0 mm, respectively. The range of the mean ± 2 standard deviations of the IOP adjusted for the parameters of the multivariable model was 9.0 to 18.1 mmHg versus 9.2–20.2 mmHg for the unadjusted IOP. In the age group of 50 to 55 years, the age-adjusted IOP range (mean ± 2 standard deviations) was 9 to 18 mmHg, and in the age group of ≥75 years, it was 8 to 18 mmHg.

Conclusions

IOP physiologically depends on a multitude of systemic and ocular factors including age and blood pressure. These physiological associations of the IOP may be taken into account in the definition of the normal range of the IOP.

Distribution of IOP measured with an air puff tonometer in a young population

Purpose

To determine the normal range of intraocular pressure (IOP) in the young and its association with certain corneal parameters using a non-contact device.

Methods

Subjects were selected from students of Mashhad University of Medical Sciences through stratified sampling. All participants had visual acuity testing, corneal imaging, a comprehensive slit-lamp examination by an ophthalmologist, and IOP measurement using a non-contact air-puff tonometer.

Results

Of the 1280 invitees, 1073 (83.8%) participated, and 1027 were eligible. Mean IOP was 16.38 mmHg [95% confidence interval (CI): 16.22–16.53] in the total sample, 16.14 mmHg (95% CI: 15.84–16.45) in men, and 16.48 mmHg (95% CI: 16.31–16.66) in women. There was a significant IOP difference between myopes and emmetropes (P = 0.031). Based on the multiple linear regression model, IOP associated directly with age and central corneal thickness (CCT), and inversely with corneal diameter, spherical equivalent (SE), and keratoconus. Based on standardized coefficients of the regression model, CCT and SE had the strongest association with IOP.

Conclusions

In the present study, we demonstrated the IOP distribution in a young population using a non-contact method. CCT and SE were strongly associated with IOP.

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

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

Cardiovascular medication and intraocular pressure: results from the Gutenberg Health Study

BACKGROUND

Intraocular pressure (IOP) is well known to be associated with blood pressure and other cardiovascular risk factors. The influence of systemic cardiovascular, in particular antihypertensive, medication on IOP is still controversial. This study analyses the association between the use of cardiovascular medications and IOP in a large European cohort.

METHODS

The Gutenberg Health Study is a population-based, prospective,observational cohort study in mid-western Germany. IOP was measured using a non-contact tonometer. The medication classes examined were peripheral vasodilators, diuretics, β-blockers (overall, selective and non-selective), calcium channel blockers, renin-angiotensin blockers (overall, ACE inhibitors and angiotensin-receptor blockers), nitrates, other antihypertensive medications, aspirin and statins. Subjects with missing IOP values, topical IOP-lowering medication or previous ocular surgery were excluded. In total, 13 527 subjects were enrolled in this study. Association analyses between medication use and IOP were performed using multivariable linear regression (p<0.0038).

RESULTS

Neither selective nor non-selective systemic β-blocker intake was associated with statistically significant lower IOP (-0.12 mm Hg, p=0.054 and -0.70 mm Hg, p=0.037, respectively). IOP was not associated with the use of ACE inhibitors after adjustment for body mass index, systolic blood pressure and central corneal thickness (0.11 mm Hg; p=0.07).

CONCLUSIONS

None of the cardiovascular medications, in particular systemic β-blocking agents, showed an association with IOP in non-glaucoma subjects. The long-term drift phenomenon of topical and systemic β-blocker might explain this result. Our results suggest that systemic β-blockers have a negligible effect on IOP reduction.

Distribution of intraocular pressure, central corneal thickness and vertical cup-to-disc ratio in a healthy Iranian population: the Yazd Eye Study

PURPOSE

To determine the distribution of intraocular pressure (IOP), central corneal thickness (CCT) and vertical cup-to-disc ratio (VCDR) in the healthy Iranian population.

METHODS

This population-based, epidemiologic study evaluated Iranian aged 40-80 years, residing in Yazd, Iran, in 2010-2011. Eligible subjects were selected by cluster random sampling. Each participant underwent an interview and ophthalmologic examination including slit lamp examination, Goldmann applanation tonometry, binocular optic disc evaluation, stereoscopic fundus photography, ultrasonic pachymetry and visual field testing.

RESULTS

Of 2320 eligible individuals, 2098 subjects (response rate of 90.4%) participated in the study. One eye from 1159 subjects (total of 2262 normal eyes) were randomly selected for the purpose of the study. Mean age was 53.1 ± 9.6 years. Mean IOP, CCT and VCDR were 14.2 ± 2.5 mmHg, 543 ± 37 μm and 0.32 ± 0.14, respectively. Multiple regression analysis showed a significant correlation between IOP and age (regression coefficient = 0.02 per year, p = 0.015), CCT (regression coefficient = 0.02 per micron, p < 0.001), Spherical equivalent (regression coefficient = -0.15 per dioptre, p = 0.0.024) and smoking (regression coefficient = 0.89 higher for smokers, p = 0.009); it also showed a significant correlation between CCT with spherical equivalent (regression coefficient = 3.6 per dioptre, p = 0.002) and IOP (regression coefficient = 3.6 per mmHG, p < 0.001). There was no significant correlation with VCDR.

CONCLUSIONS

Mean IOP, CCT and VCDR were 14.2 ± 2.5 mmHg, 543 ± 35 μm and 0.32 ± 0.14, respectively, in healthy Iranians that is different from other ethnicities. It seems advisable to pay attention to ethnicity for interpretation of each person's variables.

Relationships Between Anthropometric Measurements and Intraocular Pressure: The Korea National Health and Nutrition Examination Survey

PURPOSE

To evaluate the relationship between intraocular pressure (IOP) and various anthropometric measures.

DESIGN

A population-based cross-sectional study.

METHODS

A total of 5008 participants, 2080 men and 2928 women ≥19 years of age were included from the Korea National Health and Nutrition Examination Survey V database, focusing on the years 2010 and 2011. We selected IOP in the right eye of a normal healthy population as the outcome variable of our study. We analyzed the relationship between IOP and anthropometric parameters using dual-energy X-ray absorptiometry by sex. Lean body mass was calculated as total body mass minus fat mass. We used general linear models and logistic regression analysis to evaluate risk factors of high IOP. Our main outcome measure was correlation between anthropometric data and IOP.

RESULTS

In multivariate general linear models, greater body mass index (BMI) and waist circumference were correlated with higher IOP for both men (BMI, β = 0.053, P = .026; waist circumference, β = 0.016, P = .067) and women (BMI, β = 0.074, P < .001; waist circumference, β = 0.028, P < .001). Greater fat mass (β = 0.027, P = .037) and fat mass/lean body mass (β = 1.170, P = .06) were correlated with higher IOP, while greater lean body mass/weight (β = -3.188, P = .025), lean body mass/BMI (β = -1.379, P = .002), appendicular skeletal muscle mass/BMI (β = -2.270, P = .022), and bone mineral content/BMI (β = -11.653, P = .031) were correlated with lower IOP in women, but not in men (P > .10).

CONCLUSIONS

In healthy women, greater fat mass was associated with higher IOP, and greater muscle mass was associated with lower IOP after adjusting for weight and BMI. Fat and muscle influenced IOP in women independently.

Postprandial Glucose as a Risk Factor for Elevated Intraocular Pressure

The aim of this study was to investigate the association between postprandial glucose and intraocular pressure in a relatively healthy population. We examined 1,439 adults getting a health check-up in a health promotion center at Tri-Service General Hospital (TSGH) in Taiwan between 2012 and 2013. All participants underwent examinations to measure metabolic variables and intraocular pressure. Multiple linear regression analyses were performed to assess the relationship between postprandial glucose and intraocular pressure. The levels of postprandial glucose were divided into quartiles with subjects in the lowest quartile being regarded as the reference group to perform quartile-based analysis. Covariate adjustment was designed for three models for further analysis. Subjects with higher quartiles of postprandial glucose level had a higher systolic blood pressure, a greater waist circumference and an elevated fasting glucose level (all p < 0.001). The β coefficient with adjusted covariates showed a significant positive association between postprandial glucose and intraocular pressure. The trends of intraocular pressure across increasing quartiles of postprandial glucose were statistically significant (all p for trend < 0.001). Thus, higher levels of postprandial glucose positively correlated with elevated intraocular pressure.

Associations with intraocular pressure across Europe: The European Eye Epidemiology (E3) Consortium

Raised intraocular pressure (IOP) is the most important risk factor for developing glaucoma, the second commonest cause of blindness globally. Understanding associations with IOP and variations in IOP between countries may teach us about mechanisms underlying glaucoma. We examined cross-sectional associations with IOP in 43,500 European adults from 12 cohort studies belonging to the European Eye Epidemiology (E³) consortium. Each study conducted multivariable linear regression with IOP as the outcome variable and results were pooled using random effects meta-analysis. The association of standardized study IOP with latitude was tested using meta-regression. Higher IOP was observed in men (0.18 mmHg; 95 % CI 0.06, 0.31; P = 0.004) and with higher body mass index (0.21 mmHg per 5 kg/m²; 95 % CI 0.14, 0.28; P < 0.001), shorter height (−0.17 mmHg per 10 cm; 95 % CI –0.25, −0.08; P < 0.001), higher systolic blood pressure (0.17 mmHg per 10 mmHg; 95 % CI 0.12, 0.22; P < 0.001) and more myopic refraction (0.06 mmHg per Dioptre; 95 % CI 0.03, 0.09; P < 0.001). An inverted U-shaped trend was observed between age and IOP, with IOP increasing up to the age of 60 and decreasing in participants older than 70 years. We found no significant association between standardized IOP and study location latitude (P = 0.76). Novel findings of our study include the association of lower IOP in taller people and an inverted-U shaped association of IOP with age. We found no evidence of significant variation in IOP across Europe. Despite the limited range of latitude amongst included studies, this finding is in favour of collaborative pooling of data from studies examining environmental and genetic determinants of IOP in Europeans.

Distribution of intraocular pressure and its determinants in an Iranian adult population

AIM

To determine the distribution of intraocular pressure (IOP) and its determinants in an Iranian population.

METHODS

In a cross-sectional survey, random cluster sampling was conducted from the 40-64 years old population of Shahroud, in the north of Iran. All participants had optometry and ophthalmic exams. IOP was determined using the Goldmann tonometry method and biometric components were measured.

RESULTS

Of the 6311 people selected for the study, 5190 (82.2%) participated. The mean age of the participants was 50.9±6.2y and 58.7% of them were female. Mean IOP was 12.87±2.27 mm Hg. In this study 0.3% of the participants had an IOP higher than 21 mm Hg. The multiple linear regression model revealed that sex (Coef=-0.30; 95% CI: -0.43 to -0.17), diabetes (Coef=0.43; 95% CI: 0.19 to 0.67), high systolic blood pressure (Coef=0.02; 95% CI: 0.01 to 0.02), high body mass index (BMI) (Coef=0.03; 95% CI: 0.01 to 0.04), higher education (Coef=0.02, 95% CI: 0.01 to 0.04), thicker central corneal thickness (Coef=0.01; 95% CI: 0.01 to 0.02), and myopic shift in spherical equivalent (Coef=-0.14; 95% CI: -0.18 to -0.10) significantly correlated with high IOP.

CONCLUSION

The IOP in this 40-64 years old population is low overall. In the north of Iran, average IOP is statistically significantly correlated with female sex, diabetes, higher BMI, systolic blood pressure, higher education, thicker cornea, and myopic refractive error.