Does smoking affect intraocular pressure? Findings from the Blue Mountains Eye Study

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.

Former smoking as a risk factor for visual field progression in exfoliation glaucoma patients in Sweden

PURPOSE

The present study aimed to identify whether former smoking was a risk factor for visual field progression in exfoliation glaucoma patients.

METHODS

Prospective nonrandomised cohort study. The study included patients diagnosed with exfoliation glaucoma. All included patients were followed for three years (± three months) with reliable visual fields. At least five reliable visual fields needed to be included in the study. Exfoliation glaucoma was defined using the European Glaucoma Society Guidelines. The visual fields were tested using the 24-2 test strategy of the Humphrey Field Analyzer. Smoking was assessed through questionnaires. Outcomes: Visual field progression. Three different approaches were used: difference in mean deviation (MD), rate of progression (ROP), and guided progression analysis (GPA).

RESULTS

In total, n = 113 patients were included; among them, n = 57 were smokers. Smoking was a significant predictor for visual field progression in the three models (MD/ROP/GPA) studied (p = 0.01/p = 0.001/p ≤ 0.001), even adjusting for intraocular pressure (IOP). Other predictors were included in the MD model: IOP at diagnosis (p = 0.04) and selective laser trabeculoplasty (SLT) treatment (p = 0.01). Other predictors were in the ROP model: Visual field index (p = 0.005), number of medications (p = 0.001) and SLT treatment (p = 0.001). The number of medications was another predictor in the GPA model (p = 0.002).

CONCLUSIONS

Former smoking induced visual field deterioration in all models studied. Smoking status should be considered when establishing the glaucoma diagnosis. Increased glaucoma care should be provided to former smokers to slow the progression of the disease.

Smoking, Corneal Biomechanics, and Glaucoma: Results From Two Large Population-Based Cohorts

Purpose

Smoking may influence measured IOP through an effect on corneal biomechanics, but it is unclear whether this factor translates into an increased risk for glaucoma. This study aimed to examine the association of cigarette smoking with corneal biomechanical properties and glaucoma-related traits, and to probe potential causal effects using Mendelian randomization (MR).

Methods

Cross-sectional analyses within the UK Biobank (UKB) and Canadian Longitudinal Study on Aging (CLSA) cohorts. Multivariable linear and logistic regression models were used to assess associations of smoking (status, intensity, and duration) with corneal hysteresis (CH), corneal resistance factor, IOP, inner retinal thicknesses, and glaucoma. Two-sample MR analyses were performed.

Results

Overall, 68,738 UKB (mean age, 56.7 years; 54.7% women) and 22 845 CLSA (mean age, 62.7 years; 49.1% women) participants were included. Compared with nonsmokers, smokers had a higher CH (UKB, +0.48 mm Hg; CLSA, +0.57 mm Hg; P < 0.001) and corneal resistance factor (UKB, +0.47 mm Hg; CLSA, +0.60 mm Hg; P < 0.001) with evidence of a dose-response effect in both studies. Differential associations with Goldmann-correlated IOP (UKB, +0.25 mm Hg; CLSA, +0.36 mm Hg; P < 0.001) and corneal-compensated IOP (UKB, -0.28 mm Hg; CLSA, -0.32 mm Hg; P ≤ 0.001) were observed. Smoking was not associated with inner retinal thicknesses or glaucoma status in either study. MR provided evidence for a causal effect of smoking on corneal biomechanics, especially higher CH.

Conclusions

Cigarette smoking seems to increase corneal biomechanical resistance to deformation, but there was little evidence to support a relationship with glaucoma. This outcome may result in an artefactual association with measured IOP and could account for discordant results with glaucoma in previous epidemiological studies.

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.

Comparative analysis of tear cytokines in patients with glaucoma, ocular hypertension, and healthy controls

PURPOSE

To investigate the ocular surface inflammation in patients with primary open angle glaucoma and ocular hypertension by analyzing tears and to compare findings with healthy controls.

METHODS

Observational case-control study. Tear samples were collected by 5 µl microcapillary tube from 24 patients with glaucoma treated by antiglaucoma drops, 9 non-treated patients with ocular hypertension and 45 healthy controls. Tears were analyzed from right eye by multiplex Bio-Plex system for the presence of 6 cytokines: IL1β, IL10, IL4, IFNγ, MIF and VEGF.

RESULTS

Significantly higher concentrations of IL1β and IL10 (glaucoma or ocular hypertension vs. healthy controls, p < 0.0001), VEGF (glaucoma vs. ocular hypertension, p < 0.05; ocular hypertension vs. healthy controls, p < 0.02) and MIF (glaucoma vs. healthy controls, p < 0.03) were detected in patients' tears. Both patient groups have activated to a significantly lower extent the Th1 pathway represented by IFNγ than Th2 pathway represented by IL10 (p < 0.001) and, at the same time, the IFNγ/IL4 ratio was significantly increased in healthy controls (p < 0.001) and patients with ocular hypertension (p < 0.02) compared to glaucoma individuals.

CONCLUSION

This study shows that secretion of inflammation-related cytokines by conjunctival cells is increased in both, glaucoma and ocular hypertension patients and can be detected in their tears. Nevertheless, data indicates stronger ocular surface inflammation in non-treated follow-up patients diagnosed with ocular hypertension than in glaucoma subjects treated by antiglaucoma drops.

The impact of Alzheimer's disease risk factors on the pupillary light response

Alzheimer's disease (AD) is the leading cause of dementia, and its prevalence is increasing and is expected to continue to increase over the next few decades. Because of this, there is an urgent requirement to determine a way to diagnose the disease, and to target interventions to delay and ideally stop the onset of symptoms, specifically those impacting cognition and daily livelihood. The pupillary light response (PLR) is controlled by the sympathetic and parasympathetic branches of the autonomic nervous system, and impairments to the pupillary light response (PLR) have been related to AD. However, most of these studies that assess the PLR occur in patients who have already been diagnosed with AD, rather than those who are at a higher risk for the disease but without a diagnosis. Determining whether the PLR is similarly impaired in subjects before an AD diagnosis is made and before cognitive symptoms of the disease begin, is an important step before using the PLR as a diagnostic tool. Specifically, identifying whether the PLR is impaired in specific at-risk groups, considering both genetic and non-genetic risk factors, is imperative. It is possible that the PLR may be impaired in association with some risk factors but not others, potentially indicating different pathways to neurodegeneration that could be distinguished using PLR. In this work, we review the most common genetic and lifestyle-based risk factors for AD and identify established relationships between these risk factors and the PLR. The evidence here shows that many AD risk factors, including traumatic brain injury, ocular and intracranial hypertension, alcohol consumption, depression, and diabetes, are directly related to changes in the PLR. Other risk factors currently lack sufficient literature to make any conclusions relating directly to the PLR but have shown links to impairments in the parasympathetic nervous system; further research should be conducted in these risk factors and their relation to the PLR.

Critical review on emerging health effects associated with the indoor air quality and its sustainable management

Indoor air quality (IAQ) is one of the fundamental elements affecting people's health and well-being. Currently, there is a lack of awareness among people about the quantification, identification, and possible health effects of IAQ. Airborne pollutants such as volatile organic compounds (VOCs), particulate matter (PM), sulfur dioxide (SO2), carbon monoxide (CO), nitrous oxide (NO), polycyclic aromatic hydrocarbons (PAHs) microbial spores, pollen, allergens, etc. primarily contribute to IAQ deterioration. This review discusses the sources of major indoor air pollutants, molecular toxicity mechanisms, and their effects on cardiovascular, ocular, neurological, women, and foetal health. Additionally, contemporary strategies and sustainable methods for regulating and reducing pollutant concentrations are emphasized, and current initiatives to address and enhance IAQ are explored, along with their unique advantages and potentials. Due to their longer exposure times and particular physical characteristics, women and children are more at risk for poor indoor air quality. By triggering many toxicity mechanisms, including oxidative stress, DNA methylation, epigenetic modifications, and gene activation, indoor air pollution can cause a range of health issues. Low birth weight, acute lower respiratory tract infections, Sick building syndromes (SBS), and early death are more prevalent in exposed residents. On the other hand, the main causes of incapacity and early mortality are lung cancer, chronic obstructive pulmonary disease, and cardiovascular disorders. It's crucial to acknowledge anticipated research needs and implemented efficient interventions and policies to lower health hazards.

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.

Genetic Associations Between Smoking- and Glaucoma-Related Traits

Purpose

The purpose of this study was to describe the genetic relationship between smoking and glaucoma.

Methods

We used summary-level genetic data for smoking initiation, smoking intensity (cigarettes per day [CPD]), intraocular pressure (IOP), vertical cup-disc ratio, and open-angle glaucoma (OAG) to estimate global genetic correlations (rg) and perform two-sample Mendelian randomization (MR) experiments that explored relations between traits. Finally, we examined associations between smoking genetic risk scores (GRS) and smoking traits with measured IOP and OAG in Rotterdam Study participants.

Results

We identified weak inverse rg between smoking- and glaucoma-related traits that were insignificant after Bonferroni correction. However, MR analysis revealed that genetically predicted smoking initiation was associated with lower IOP (-0.18 mm Hg per SD, 95% confidence interval [CI] = -0.30 to -0.06, P = 0.003). Furthermore, genetically predicted smoking intensity was associated with decreased OAG risk (odds ratio [OR] = 0.74 per SD, 95% CI = 0.61 to 0.90, P = 0.002). In the Rotterdam Study, the smoking initiation GRS was associated with lower IOP (-0.09 mm Hg per SD, 95% CI = -0.17 to -0.01, P = 0.04) and lower odds of OAG (OR = 0.84 per SD, 95% CI = 0.73 to 0.98, P = 0.02) in multivariable-adjusted analyses. In contrast, neither smoking history nor CPD was associated with IOP (P ≥ 0.38) or OAG (P ≥ 0.54). Associations between the smoking intensity GRS and glaucoma traits were null (P ≥ 0.13).

Conclusions

MR experiments and GRS generated from Rotterdam Study participants support an inverse relationship between smoking and glaucoma.

Translational Relevance

Understanding the genetic drivers of the inverse relationship between smoking and glaucoma could yield new insights into glaucoma pathophysiology.

The Association between Serum Lipids and Intraocular Pressure in 2 Large United Kingdom Cohorts

PURPOSE

Serum lipids are modifiable, routinely collected blood test features associated with cardiovascular health. We examined the association of commonly collected serum lipid measures (total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], and triglycerides) with intraocular pressure (IOP).

DESIGN

Cross-sectional study in the UK Biobank and European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohorts.

PARTICIPANTS

We included 94 323 participants from the UK Biobank (mean age, 57 years) and 6230 participants from the EPIC-Norfolk (mean age, 68 years) cohorts with data on TC, HDL-C, LDL-C, and triglycerides collected between 2006 and 2009.

METHODS

Multivariate linear regression adjusting for demographic, lifestyle, anthropometric, medical, and ophthalmic covariables was used to examine the associations of serum lipids with corneal-compensated IOP (IOPcc).

MAIN OUTCOME MEASURES

Corneal-compensated IOP.

RESULTS

Higher levels of TC, HDL-C, and LDL-C were associated independently with higher IOPcc in both cohorts after adjustment for key demographic, medical, and lifestyle factors. For each 1-standard deviation increase in TC, HDL-C, and LDL-C, IOPcc was higher by 0.09 mmHg (95% confidence interval [CI], 0.06-0.11 mmHg; P < 0.001), 0.11 mmHg (95% CI, 0.08-0.13 mmHg; P < 0.001), and 0.07 mmHg (95% CI, 0.05-0.09 mmHg; P < 0.001), respectively, in the UK Biobank cohort. In the EPIC-Norfolk cohort, each 1-standard deviation increase in TC, HDL-C, and LDL-C was associated with a higher IOPcc by 0.19 mmHg (95% CI, 0.07-0.31 mmHg; P = 0.001), 0.14 mmHg (95% CI, 0.03-0.25 mmHg; P = 0.016), and 0.17 mmHg (95% CI, 0.06-0.29 mmHg; P = 0.003). An inverse association between triglyceride levels and IOP in the UK Biobank (-0.05 mmHg; 95% CI, -0.08 to -0.03; P < 0.001) was not replicated in the EPIC-Norfolk cohort (P = 0.30).

CONCLUSIONS

Our findings suggest that serum TC, HDL-C, and LDL-C are associated positively with IOP in 2 United Kingdom cohorts and that triglyceride levels may be associated negatively. Future research is required to assess whether these associations are causal in nature.

The Adverse Effects of Air Pollution on the Eye: A Review

Air pollution is inevitably the result of human civilization, industrialization, and globalization. It is composed of a mixture of gases and particles at harmful levels. Particulate matter (PM), nitrogen oxides (NOx), and carbon dioxides (CO₂) are mainly generated from vehicle emissions and fuel consumption and are the main materials causing outdoor air pollution. Exposure to polluted outdoor air has been proven to be harmful to human eyes. On the other hand, indoor air pollution from environmental tobacco smoking, heating, cooking, or poor indoor ventilation is also related to several eye diseases, including conjunctivitis, glaucoma, cataracts, and age-related macular degeneration (AMD). In the past 30 years, no updated review has provided an overview of the impact of air pollution on the eye. We reviewed reports on air pollution and eye diseases in the last three decades in the PubMed database, Medline databases, and Google Scholar and discussed the effect of various outdoor and indoor pollutants on human eyes.

Relationship between Intraocular Pressure and Coffee Consumption in a Japanese Population without Glaucoma: The Nagahama Study

PURPOSE

To evaluate the association between daily coffee consumption and intraocular pressure (IOP) in healthy persons without glaucoma and the association between daily coffee consumption and history of glaucoma.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 9850 individuals participated in the first follow-up of the Nagahama Prospective Cohort for Comprehensive Human Bioscience (the Nagahama Study) conducted between 2013 and 2016.

METHODS

All participants underwent a standardized ophthalmic examination. Self-reporting questionnaires were completed by all participants. First, the association between habitual coffee consumption and IOP among nonglaucoma individuals was evaluated by a multivariate linear regression analysis, adjusting for possible confounders. Second, the association between habitual coffee consumption and history of glaucoma also was evaluated using a multivariate logistic regression analysis.

MAIN OUTCOME MEASURES

The association between habitual coffee consumption and IOP among nonglaucoma individuals.

RESULTS

Of 9850 participants, 9418 did not have history of glaucoma. Among these participants, the mean ± standard deviation IOP of both eyes was 14.7 ± 2.9 mmHg. The multivariate regression analysis revealed that habitual coffee consumption was associated significantly with IOP (P < 0.001): the higher the consumption of coffee, the lower the IOP of an individual. The IOP of the group who consumed coffee most frequently (3 times daily or more) was 0.4 mmHg lower (95% confidence interval, 0.2-0.5 mmHg lower) than that of the group that consumed coffee least frequently (less than once daily). However, the logistic regression analysis showed that habitual coffee consumption was not associated significantly with history of glaucoma (P = 0.53).

CONCLUSIONS

Frequent coffee consumption was associated with a slightly lower IOP in people without glaucoma but was not associated with a decreased risk of glaucoma developing. Additional experimental studies are needed to examine the effects of coffee on IOP and glaucoma risk.

Illicit drugs: Effects on eye

There is a myriad of changes that can be produced in the eye by toxic drugs ranging from mild/no symptoms to severe loss of vision from endophthalmitis. The routes of administration include oral ingestion, smoking, nasal inhalation, intravenous injection, topical application or application to other mucosal surfaces. It is important to recognize certain clinical signs and symptoms in the eye produced by these toxins. This article describes in brief some of the ocular effects of commonly abused drugs. For identification of a particular poisoning, in addition to the clinical presentation, pulse, blood pressure, respiration and body temperature, pupillary size, pupillary reaction to light, ocular convergence and nystagmus can be useful indicators of the type of drug the patient is exposed to. Unmasking these features help the clinician in an early and accurate diagnosis of the offending drug as well as timely management.

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.

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.

Prevalence of increased intraocular pressure in patients with Graves' ophthalmopathy and association with ophthalmic signs and symptoms in the north-west of Iran

Introduction

Graves’ ophthalmopathy (GO) is the most common extra-thyroidal manifestation of Graves' disease and is characterized by multiple ocular symptoms such as eyelid retraction, lid lag, proptosis, elevated intraocular pressure (IOP) and ultimately loss of vision. We aimed to investigate the prevalence of increased IOP in Graves' patients and association with ophthalmic signs and symptoms in north-west of Iran.

Materials and methods

This descriptive cross-sectional study recruited 93 patients with GO who were diagnosed based on clinical and laboratory examinations. A complete ocular examination and IOP measurements on forward gaze were performed using Goldman applanation tonometer.

Results

In this study, 93 patients with GO were evaluated from 2016 to 2017. Among these patients, 67 (72.05%) were female and 27 (27.95%) were male. The most common complaints of patients were lid retraction (62.36%), puffy eyelids (58.06%) and proptosis (46.23%), respectively. The duration of disease was 0–24 months in most patients. Most subjects were at grade 3 according to NOSPECS classification. Nine patients (9.6%) had an IOP greater than or equal to 21 mmHg. The mean IOP in subjects was 16.61±3.42 mmHg. The mean IOP in males and smokers was significantly higher than that of females and nonsmokers. The mean IOP increased significantly with a higher grade of disease, duration of disease, age and smoking.

Conclusions

According to the results, females comprised the majority of the study population, while ocular complications were more prevalent among males. The highest IOP was seen in old cases of GO. The most prevalent ocular signs in patients were eyelid retraction and periorbital edema. The least prevalent sign was glaucomatous optic neuropathy. In this study, the prevalence of intra-ocular hypertension was higher than that of the general population, especially in males, old cases with a drug history of antithyroid medication and smokers.

Long Anterior Lens Zonules and Intraocular Pressure

Purpose

To investigate the relation between intraocular pressure (IOP) and the idiopathic long anterior zonule (LAZ) trait.

Methods

Patients presenting for primary eye care were examined for LAZ, identified as radially oriented zonular fibers with central extension >1.0 mm beyond the normal anterior lens insertion zone (estimated via slit lamp beam length). Ocular, systemic health, and lifestyle data were collected via comprehensive exam and questionnaire. Multivariate regression was used to assess the relationship between IOP (Goldmann) and LAZ.

Results

There were 2169 non-LAZ and 129 LAZ subjects (mean age: 49.8 ± 15.0 vs. 62.6 ± 10.2 years; 63.6% vs. 76.0% female; 83.2% vs. 91.5% African American). Right eyes with >trace LAZ (n = 59 of 110) had higher unadjusted mean IOP than control eyes (16.4 ± 3.3 vs. 15.0 ± 3.3 mm Hg, P = 0.005), and with control for numerous factors, LAZ eyes had an average IOP of approximately 1.3 ± 0.4 mm Hg higher (P = 0.003) than non-LAZ eyes. Final model covariates included sex (P = 0.001); spherical-equivalent refractive error (D; P < 0.0001); body mass index (kg/m²; P < 0.001); presence of diabetes (P < 0.001); having >high school education (P < 0.001); systolic blood pressure (mm Hg; P < 0.0001); being an ever smoker (P = 0.006); and having history of any site cancer (P = 0.01).

Conclusions

The LAZ trait, with potential prevalence near 2%, was associated with a higher IOP. This observation is consistent with the hypothesis that the trait is a marker for underlying mechanisms that elevate glaucoma risk.

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

PURPOSE

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

DESIGN

Secondary analysis of randomized clinical trial data.

METHODS

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

STUDY POPULATION

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

MAIN OUTCOME MEASURES

Independent systemic disease risk factors associated with IOP.

RESULTS

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

CONCLUSIONS

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

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.

The association between cigarette smoking and primary open-angle glaucoma: a systematic review

Glaucoma is one of the most common causes of irreversible blindness, globally. Findings from the Blue Mountain Eye Study suggest a moderate positive association between smoking and increased IOP (a significant risk factor for glaucoma). The previous two reviews investigating the association between smoking and primary open-angle glaucoma (POAG) show inconsistent findings and do not include recent studies investigating the dose-response effect of smoking. The current study aims to conduct an up-to-date, comprehensive evaluation of the existing literature. Identification of relevant existing literature was performed by an online search in MEDLINE for studies published from 1st January 1946 to 5th February 2015. The MESH headings (keywords) included "open-angle glaucoma" and "cigarette" or "smoking" or "tobacco". Two independent reviewers assessed the eligibility of each report based on predefined inclusion criteria. Odds ratios and 95 % confidence intervals (95 % CIs) were obtained from studies, for the change in risk of glaucoma due to both past and current smoking. Of the 26 abstracts reviewed, 17 papers were included in the final analysis. Nine of these were case-control studies, five cohort studies and three cross-sectional in design. Six of the case-control studies found a positive association between smoking and POAG, unlike the remaining studies. However, two relatively recent, large studies (including one prospective cohort study) investigating the effect of smoking dose have found a significant increase in risk of POAG in very heavy smokers. There is limited evidence for a causal association between tobacco smoking and POAG. The evidence for a link between current smoking and POAG appears stronger than that of past smoking, but recent studies suggest that heavy smoking may increase the risk of POAG. Future studies must further investigate the possible positive association between heavy smoking and POAG by stratifying participants by pack years and age.

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.

Associations of blood heavy metal levels with intraocular pressure

PURPOSE

Whether or which blood heavy metal levels (BHMLs) influence elevating intraocular pressure (IOP) are unknown. We examined the relationship among blood lead, mercury, and cadmium levels, blood pressure (BP), and IOP and assessed whether BP mediates these BHMLs-IOP associations.

METHODS

We analyzed data on 8371 adult (≥20 years) from the Korea National Health and Nutrition Examination Survey from 2008 to 2012. Mediation analysis was used to examine the contribution of BP to the BHMLs-IOP relationship.

RESULTS

IOP and three BHMLs were significantly associated with systolic and diastolic BP. But IOP was associated with only blood lead and mercury levels. BP significantly mediated lead-IOP and mercury-IOP associations: BP accounted for 20.5% and 14.2% of the association with IOP. Blood lead and mercury levels were significantly associated with IOP.

CONCLUSIONS

BP significantly mediates the effects of those blood lead and mercury levels on IOP outcome. Prospective studies are needed to further examine the causal pathway from BHMLs to IOP elevation.

Update on Normal Tension Glaucoma

Normal tension glaucoma (NTG) is labelled when typical glaucomatous disc changes, visual field defects and open anterior chamber angles are associated with intraocular pressure (IOP) constantly below 21 mmHg. Chronic low vascular perfusion, Raynaud's phenomenon, migraine, nocturnal systemic hypotension and over-treated systemic hypertension are the main causes of normal tension glaucoma. Goldmann applanation tonometry, gonioscopy, slit lamp biomicroscopy, optical coherence tomography and visual field analysis are the main tools of investigation for the diagnosis of NTG. Management follows the same principles of treatment for other chronic glaucomas: To reduce IOP by a substantial amount, sufficient to prevent disabling visual loss. Treatment is generally aimed to lower IOP by 30% from pre-existing levels to 12-14 mmHg. Betaxolol, brimonidine, prostaglandin analogues, trabeculectomy (in refractory cases), systemic calcium channel blockers (such as nifedipine) and 24-hour monitoring of blood pressure are considered in the management of NTG. The present review summarises risk factors, causes, pathogenesis, diagnosis and management of NTG.

Associations with Intraocular Pressure in a Large Cohort: Results from the UK Biobank

PURPOSE

To describe the associations of physical and demographic factors with Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) in a British cohort.

DESIGN

Cross-sectional study within the UK Biobank, a large-scale multisite cohort study in the United Kingdom.

PARTICIPANTS

We included 110 573 participants from the UK Biobank with intraocular pressure (IOP) measurements available. Their mean age was 57 years (range, 40-69 years); 54% were women, and 90% were white.

METHODS

Participants had 1 IOP measurement made on each eye using the Ocular Response Analyzer noncontact tonometer. Linear regression models were used to assess the associations of IOP with physical and demographic factors.

MAIN OUTCOME MEASURES

The IOPg and IOPcc.

RESULTS

The mean IOPg was 15.72 mmHg (95% confidence interval [CI], 15.70-15.74 mmHg), and the mean IOPcc was 15.95 mmHg (15.92-15.97 mmHg). After adjusting for covariates, IOPg and IOPcc were both significantly associated with older age, male sex, higher systolic blood pressure (SBP), faster heart rate, greater myopia, self-reported glaucoma, and colder season (all P < 0.001). The strongest determinants of both IOPg and IOPcc were SBP (partial R(2): IOPg 2.30%, IOPcc 2.26%), followed by refractive error (IOPg 0.60%, IOPcc 1.04%). The following variables had different directions of association with IOPg and IOPcc: height (-0.77 mmHg/m IOPg; 1.03 mmHg/m IOPcc), smoking (0.19 mmHg IOPg, -0.35 mmHg IOPcc), self-reported diabetes (0.41 mmHg IOPg, -0.05 mmHg IOPcc), and black ethnicity (-0.80 mmHg IOPg, 0.77 mmHg IOPcc). This suggests that height, smoking, diabetes, and ethnicity are related to corneal biomechanical properties. The increase in both IOPg and IOPcc with age was greatest among those of mixed ethnicities, followed by blacks and whites. The same set of covariates explained 7.4% of the variability of IOPcc but only 5.3% of the variability of IOPg.

CONCLUSIONS

This analysis of associations with IOP in a large cohort demonstrated that some variables clearly have different associations with IOPg and IOPcc, and that these 2 measurements may reflect different biological characteristics.

Comparison of risk factors for initial central scotoma versus initial peripheral scotoma in normal-tension glaucoma

Purpose

To investigate the risk factors for initial central scotoma (ICS) compared with initial peripheral scotoma (IPS) in normal-tension glaucoma (NTG).

Methods

Fifty-six NTG patients (56 eyes) with an ICS and 103 NTG patients (103 eyes) with an IPS were included. Retrospectively, the differences were assessed between the two groups for baseline characteristics, ocular factors, systemic factors, and lifestyle factors. Also, the mean deviation of visual field was compared between the two groups.

Results

Patients from both ICS and IPS groups were of similar age, gender, family history of glaucoma, and follow-up periods. Frequency of disc hemorrhage was significantly higher among patients with ICS than in patients with IPS. Moreover, systemic risk factors such as hypotension, migraine, Raynaud's phenomenon, and snoring were more prevalent in the ICS group than in the IPS group. There were no statistical differences in lifestyle risk factors such as smoking or body mass index. Pattern standard deviation was significantly greater in the ICS group than in the IPS group, but the mean deviation was similar between the two groups.

Conclusions

NTG Patients with ICS and IPS have different profiles of risk factors and clinical characteristics. This suggests that the pattern of initial visual field loss may be useful to identify patients at higher risk of central field loss.

Association of smoking with intraocular pressure in middle-aged and older Japanese residents

OBJECTIVES

To clarify whether smoking was associated with elevated intraocular pressure (IOP) and to evaluate the interrelationship among IOP, blood viscosity, and smoking.

METHODS

This cross-sectional study analyzed health examination data obtained between 2001 and 2004 from 1113 individuals (829 men and 284 women), ranging in age from 28 to 79 years, who had not undergone any ocular surgery or medical treatment for hypertension, ocular hypertension, and glaucoma.

RESULTS

Multiple-regression analysis showed that systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), and number of cigarettes smoked per day had a significantly positive association with IOP in men (P < 0.05). In women also, SBP, DBP, and BMI were positively related to IOP (P < 0.05). On the contrary, age had a significant negative association with IOP in both sexes (P < 0.01). Analysis of covariance and multiple logistic regression analyses showed that the adjusted mean IOP and the multivariate odds ratios for IOP increased with increasing cigarette consumption in men (P for trend = 0.01 and 0.06, respectively). Analysis of covariance found that smoking was significantly associated with both high IOP and high hematocrit in men (P for trend <0.05); however, the adjusted mean IOP values were higher in smokers than in nonsmokers, regardless of the hematocrit level.

CONCLUSIONS

The results of this study suggested that the IOP level may be substantially affected by smoking habit in middle-aged and older Japanese men.

Association analysis of cigarette smoking with onset of primary open-angle glaucoma and glaucoma-related biometric parameters

Background

To date, studies on the role played by cigarette smoking in primary open-angle glaucoma (POAG) remains controversial. The current study evaluated cigarette smoking as a risk factor of POAG and its relationships with vertical cup-to-disc ratio (VCDR), central corneal thickness (CCT) and intraocular pressure (IOP) in a Chinese cohort.

Methods

In a total of 248 unrelated individuals including 30 juvenile-onset POAG (JOAG), 92 adult-onset POAG (AOAG) and 126 sex-matched senile cataract controls, underwent comprehensive ophthalmic examination. Their smoking was obtained and documented by questionnaire. Association of cigarette smoking with POAG was performed using logistic regression controlled for age and sex. Effects of cigarette smoking on VCDR, IOP and CCT were analyzed with multiple linear regression.

Results

In either JOAG or AOAG, no association of cigarette smoking was found with disease onset (P = 0.692 and 0.925 respectively). In controls and JOAG, no significant effects of smoking were found on VCDR, IOP or CCT (all P > 0.05). Smoking was found to be correlated with decreased CCT in AOAG and combined POAG (JOAG + AOAG) (P = 0.009 and 0.003), but no association with VCDR or IOP was observed (P > 0.05).

Conclusions

Although cigarette smoking was not found to be risk factor for onset of POAG, it was correlated with CCT in AOAG, and thus might still play a role in the disease course, especially for AOAG.

The distribution of intraocular pressure in urban and in rural populations: the Namil study in South Korea

PURPOSE

To evaluate the intraocular pressure (IOP) distribution and its regional association in the South Korean population.

DESIGN

Cross-sectional, epidemiologic study.

METHODS

All participants underwent interview and the following ocular examinations: visual acuity measurement, autorefraction, pachymetry, anterior segment evaluation, slit-lamp examination, Goldmann applanation tonometry, binocular optic disc evaluation, fundus photography, and visual field test. Patients with ocular diseases other than mild senile cataract or with history of ocular surgery were excluded.

RESULTS

A total of 3191 subjects residing in urban and rural areas were recruited. Mean IOP of patients from the urban area was significantly higher than that of those from the rural area (14.45 ± 2.67 mm Hg vs 13.53 ± 2.76 mm Hg, P < .05). There was regional difference of mean IOP, even after controlling for different demographic factors in the 2 areas (P < .05). Average IOP in the right eye of the investigated sample of South Korean population was 14.10 ± 2.74 mm Hg. Multiple regression analysis showed positive correlation between mean IOP and central corneal thickness, vertical cup-to-disc ratio, history of hypertension, smoking, and female sex, whereas IOP tended to decrease by approximately 0.2 mm Hg when age increased by 10 years.

CONCLUSIONS

This is the first population-based epidemiologic study measuring IOP in the South Korean population. Mean IOP of the urban area was found to be significantly higher than the corresponding value of the rural area. Therefore, the regional difference, as well as other various factors, has to be considered in epidemiologic study of the distribution of IOP.

Intraocular pressure and its determinants in subjects with type 2 diabetes mellitus in India

Objectives

This study was conducted to show the intraocular pressure (IOP) distribution and the factors affecting IOP in subjects with type 2 diabetes mellitus (DM) in India.

Methods

We measured the anthropometric and biochemical parameters for confirmed type 2 DM patients. A comprehensive ocular examination was performed for 1377 subjects aged > 40 years and residing in Chennai.

Results

A significant difference in IOP (mean ± standard deviation) was found between men and women (14.6±2.9 and 15.0±2.8 mmHg, p = 0.005). A significantly elevated IOP was observed among smokers, subjects with systemic hypertension and women with clinically significant macular edema (CSME). After a univariate analysis, factors associated significantly with higher IOP were elevated systolic blood pressure, elevated resting pulse rate and thicker central corneal thickness (CCT). In women, elevated glycosylated hemoglobin was associated with a higher IOP. After adjusting for all variables, the elevated resting pulse rate and CCT were found to be associated with a higher IOP.

Conclusions

Systemic hypertension, smoking, pulse rate and CCT were associated with elevated intraocular pressure in type 2 DM. Women with type 2 DM, especially those with CSME, were more prone to have an elevated IOP.

Intraocular pressure fluctuations in professional brass and woodwind musicians during common playing conditions

BACKGROUND

We investigated the effects on intraocular pressure (IOP) and blood pressure (BP) of playing brass and woodwind instruments by monitoring IOP and BP in a representative group of professional musicians under a variety of common playing conditions.

METHODS

IOP and BP measurements were recorded from 37 brass and 15 woodwind instrument players, before and after playing tones of low, middle and high frequency. We also measured IOP and BP before and during playing common exercises of 10 minutes duration, as well as after playing a sustained high-pitched tone, to test for changes in IOP under conditions of maximum effort.

RESULTS

Playing tones on brass and woodwind instruments causes a temporary elevation in IOP and BP, depending on the tone frequency: brass instrument players showed a significant elevation after playing high and middle frequency tones (p < 0.0001) whereas woodwind instrument players showed a significant increase only for high frequencies (e.g., oboe, 17 ± 2.9 mm Hg to 21 ± 4.4 mm Hg; p = 0.017). Playing a typical exercise of 10 minutes temporarily increased IOP in both groups of musicians. Finally, playing a sustained tone of high pitch caused a significant elevation in IOP in brass instrument players only (16.6 ± 3.5 mm Hg to 23.3 ± 8.9 mm Hg; p < 0.0001).

CONCLUSIONS

The temporary and sometimes dramatic elevations and fluctuations in IOP observed in this study, coupled with daily exposure to instrument play, puts professional wind instrument players at increased risk of developing glaucoma. Consequently, these musicians should be monitored for signs of glaucoma, especially those with co-existing risk factors.

Lifestyle, nutrition, and glaucoma

The only proven strategy to prevent primary open-angle glaucoma (POAG) is the use of ocular hypotensive therapy among people diagnosed with ocular hypertension. In this review, various modifiable lifestyle factors, such as exercise, diet, and cigarette smoking, that may influence intraocular pressure and that have been studied in relation to the risk of developing POAG are discussed. Epidemiologic studies on lifestyle factors are few, and the current evidence suggests that there are no environmental factors that are clearly associated with POAG; however, a few factors merit further study. This review also outlines future directions for research into the primary prevention of POAG.

Cigarette smoking and primary open angle glaucoma: a systematic review

PURPOSE

To evaluate the epidemiologic evidence for a causal association between tobacco smoking and primary open angle glaucoma (POAG).

METHODS

Systematic review, including quality assessment, of published analytical epidemiologic studies and evaluation of the evidence using established causality criteria (strength, consistency, temporality, dose response, reversibility, and biologic plausibility).

RESULTS

Eleven papers describing 9 case-control studies, 1 prospective cohort study, and a paper describing a pooled analysis based on 2 prospective cohort studies were included in the review. The methodologic quality of most included studies was poor. The strongest studies methodologically were the cohort studies on which the pooled analysis was based. Neither the prospective cohort study (rate ratio not reported) nor the pooled analysis of 2 prospective cohort studies (adjusted rate ratio 0.9) found an association between smoking and POAG. There was a significant positive association between smoking and POAG in only 2 of the case-control studies (adjusted odds ratio 2.9 and 10.8). There was no evidence of a dose-response relationship with smoking or of reversibility of effect in the studies where this was assessed.

CONCLUSIONS

This systematic review provided little evidence for a causal association between smoking and development of POAG. Given the limited evidence from high quality studies, and the possibility that flaws in many of the studies reviewed biased the results toward the null, further high quality research to confirm our conclusions is needed. However, it remains important to warn ophthalmic patients of the dangers of smoking and provide cessation support owing to the clear evidence of links between smoking and other ocular and systemic diseases.

Influencing ocular blood flow in glaucoma patients: the cardiovascular system and healthy lifestyle choices

The cardiovascular system and lifestyle choices play important roles in influencing ocular blood flow regulation in patients with glaucoma. This includes the presence of vascular risk factors, abnormal autoregulatory responses, tissue oxygenation, and mitochondrial oxidative stress. Based on this comprehensive review, novel therapeutic approaches may be considered in selected patients for preventing and (or) delaying the progression of glaucoma.

Associations between Elevated Intraocular Pressure and Glaucoma, Use of Glaucoma Medications, and 5-Year Incident Cataract

PURPOSE

To examine incident relationships between elevated intraocular pressure (IOP), open-angle glaucoma (OAG), and use of glaucoma medications with 5-year incident cataract.

DESIGN

Population-based cohort study.

PARTICIPANTS

The Australian Blue Mountains Eye Study examined 3654 participants > or =50 years old at baseline (82.4% response; 1992-1994); 2335 eligible participants were reexamined after 5 years (75.1% response; 1997-1999).

METHODS

A detailed medical and ocular history, including current medications, was taken, and a comprehensive eye examination, including applanation tonometry, automated perimetry, and lens photography, was performed at each examination. The Wisconsin system was used to grade lens photographs in assessing incident nuclear, cortical, and posterior subcapsular cataract (PSC). Data from both eyes were assessed using generalized estimating equation analyses.

MAIN OUTCOME MEASURES

Elevated IOP was defined as > or =21 mmHg. Open-angle glaucoma was diagnosed from typical glaucomatous field loss with matching optic disc cupping, without reference to IOP. Subjects without OAG or secondary or angle-closure glaucoma with IOP > 21 mmHg in either eye were classified as having ocular hypertension (OH), as were non-OAG subjects with IOP < 22 mmHg using glaucoma medications. Wisconsin levels 4 to 5 were graded as nuclear cataract, at least 5% lens involvement was graded as cortical cataract, and any PSC defined its presence.

RESULTS

The 5-year incidence of nuclear cataract was 23.4% (592/2532), or 23.1% (574/2486) after excluding subjects using glaucoma medication. A marginally significant association was found for elevated IOP or OH at baseline and incident nuclear cataract (odds ratio [OR], 1.93 [95% confidence interval (CI), 0.97-3.89], and OR, 1.83 [95% CI, 0.96-3.48], respectively) in subjects not using glaucoma medications, after multivariate adjustment. Age- and gender-adjusted analyses showed similar but statistically significant associations. The association between elevated IOP or OH and nuclear cataract was significant in multivariate analyses (OR, 2.07 [95% CI, 1.04-3.12], and OR, 1.78 [95% CI, 1.05-3.01], respectively). Use of glaucoma medications was associated with nonsignificantly increased adjusted odds for incident nuclear cataract (OR, 1.90 [95% CI, 0.92-3.92]). No associations, however, were found with incident cortical cataract or PSC.

CONCLUSIONS

Elevated IOP may increase the risk of nuclear cataract, but not that of other types. The use of glaucoma medications could magnify this risk.