Caffeine and intraocular pressure in a Nigerian population

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.

Non-drug interventions in glaucoma: Putative roles for lifestyle, diet and nutritional supplements

Glaucoma is a major ocular neurodegenerative disease characterized by progressive retinal ganglion cells degeneration and sight loss. Current treatment options have been limited to reducing intraocular pressure (IOP), known as the leading risk factor for this disease; however, glaucoma can develop even with low or normal IOP and progress despite controlling IOP values. Lifestyle, dietary habits, and supplementation may influence some of the risk factors and pathophysiological mechanisms underlying glaucoma development and progression; thus, the role of this complementary and alternative medicine in glaucoma has received great interest from both patients and ophthalmologists. We provide a summary of the current evidence concerning the relationship between lifestyle, dietary habits, and effects of supplements on the incidence and progression of glaucoma and their targets and associated mechanisms. The data suggest the existence of a therapeutic potential that needs to be further explored with both preclinical and rigorous clinical studies.

Intraocular Pressure, Glaucoma, and Dietary Caffeine Consumption: A Gene-Diet Interaction Study from the UK Biobank

PURPOSE

We examined the association of habitual caffeine intake with intraocular pressure (IOP) and glaucoma and whether genetic predisposition to higher IOP modified these associations. We also assessed whether genetic predisposition to higher coffee consumption was related to IOP.

DESIGN

Cross-sectional study in the UK Biobank.

PARTICIPANTS

We included 121 374 participants (baseline ages, 39-73 years) with data on coffee and tea intake (collected 2006-2010) and corneal-compensated IOP measurements in 2009. In a subset of 77 906 participants with up to 5 web-based 24-hour-recall food frequency questionnaires (2009-2012), we evaluated total caffeine intake. We also assessed the same relationships with glaucoma (9286 cases and 189 763 controls).

METHODS

We evaluated multivariable-adjusted associations with IOP using linear regression and with glaucoma using logistic regression. For both outcomes, we examined gene-diet interactions using a polygenic risk score (PRS) that combined the effects of 111 genetic variants associated with IOP. We also performed Mendelian randomization using 8 genetic variants associated with coffee intake to assess potential causal effects of coffee consumption on IOP.

MAIN OUTCOME MEASURES

Intraocular pressure and glaucoma.

RESULTS

Mendelian randomization analysis did not support a causal effect of coffee drinking on IOP (P > 0.1). Greater caffeine intake was associated weakly with lower IOP: the highest (≥232 mg/day) versus lowest (<87 mg/day) caffeine consumption was associated with a 0.10-mmHg lower IOP (Ptrend = 0.01). However, the IOP PRS modified this association: among those in the highest IOP PRS quartile, consuming > 480 mg/day versus < 80 mg/day was associated with a 0.35-mmHg higher IOP (Pinteraction = 0.01). The relationship between caffeine intake and glaucoma was null (P ≥ 0.1). However, the IOP PRS also modified this relationship: compared with those in the lowest IOP PRS quartile consuming no caffeine, those in the highest IOP PRS quartile consuming ≥ 321 mg/day showed a 3.90-fold higher glaucoma prevalence (Pinteraction = 0.0003).

CONCLUSIONS

Habitual caffeine consumption was associated weakly with lower IOP, and the association between caffeine consumption and glaucoma was null. However, among participants with the strongest genetic predisposition to elevated IOP, greater caffeine consumption was associated with higher IOP and higher glaucoma prevalence.

Targeting Diet and Exercise for Neuroprotection and Neurorecovery in Glaucoma

Glaucoma is a leading cause of blindness worldwide. In glaucoma, a progressive dysfunction and death of retinal ganglion cells occurs, eliminating transfer of visual information to the brain. Currently, the only available therapies target the lowering of intraocular pressure, but many patients continue to lose vision. Emerging pre-clinical and clinical evidence suggests that metabolic deficiencies and defects may play an important role in glaucoma pathophysiology. While pre-clinical studies in animal models have begun to mechanistically uncover these metabolic changes, some existing clinical evidence already points to potential benefits in maintaining metabolic fitness. Modifying diet and exercise can be implemented by patients as an adjunct to intraocular pressure lowering, which may be of therapeutic benefit to retinal ganglion cells in glaucoma.

Effects of consumption of coffee, tea, or soft drinks on open-angle glaucoma: Korea National Health and Nutrition Examination Survey 2010 to 2011

We sought to investigate the association between consumption of coffee, tea, or soft drinks and risk of open-angle glaucoma (OAG) among Koreans using nationwide population-based data. This cross-sectional survey was performed through the Korea National Health and Nutrition Examination Survey 2010 to 2011. Participants older than 19 years were included in the sample for analysis after excluding those with any missing data. The diagnosis of OAG was based on the International Society of Geographical and Epidemiological Ophthalmology criteria, and participants without glaucomatous optic neuropathy served as controls. The frequency of beverage consumption during the past 12 months was obtained through a questionnaire. Multivariate logistic regression models were used to determine the relationship between consumption of each type of beverage and prevalence of OAG. A total of 6,681 participants was included in the analysis. The prevalence of OAG was 4.4% (n = 323), including 5.4% (n = 169) among men and 3.5% (n = 154) among women. After adjusting for multiple covariates, coffee consumption was significantly associated with OAG, while no significant association was found between consumption of tea or soft drinks and OAG. Participants who drank coffee had a higher risk of having OAG compared with those who did not drink coffee (odds ratio [OR], 2.40; 95% confidence interval [CI], 1.22–4.72; p = 0.011). In sex-stratified analyses, the robust association of coffee consumption with OAG was observed in men (OR, 3.98; 95% CI, 1.71–9.25; p = 0.001) but not in women. Our results suggest that coffee consumption may affect the risk of OAG, particularly in men.

The potential health benefits of dietary natural plant products in age related eye diseases

In the past decade, there has been a tremendous increase in the number of cases of age-related eye diseases such as age-related macular degeneration (AMD), cataract, diabetic retinopathy and glaucoma. These diseases are the leading causes of visual impairment and blindness all over the world and are associated with many pathological risk factors such as aging, pollution, high levels of glucose (hyperglycaemia), high metabolic rates, and light exposure. These risk factors lead to the generation of uncontrollable reactive oxygen species (ROS), which causes oxidative stress. Oxidative stress plays a crucial role in the pathogenesis of age-related eye diseases through the activation of nuclear factor kappa B (NF-κB), vascular endothelial growth factor (VEGF), and lipid peroxidation, which leads to the production of inflammatory cytokines, angiogenesis, protein and DNA damages, apoptosis that causes macular degeneration (AMD), cataract, diabetic retinopathy and glaucoma. This review provides updated information on the beneficial effects of dietary natural plant products (DPNPs) against age-related eye diseases. In this review, supplementation of DPNPs demonstrated preventive and therapeutic effects on people at risk of or with age-related eye diseases due to their capacity to scavenge free radicals, ameliorate inflammatory molecules, neutralize the oxidation reaction that occurs in photoreceptor cells, decrease vascular endothelial growth factor and the blood-retinal barrier and increase the antioxidant defence system. However, further experiments and clinical trials are required to establish the daily doses of DPNPs that will safely and effectively prevent age-related eye diseases.

Effects of caffeine on intraocular pressure are subject to tolerance: a comparative study between low and high caffeine consumers

BACKGROUND

Caffeine has a well-established effect on intraocular pressure (IOP) and ocular perfusion pressure (OPP); however, the possible differences between low- and high-caffeine consumers remain unknown.

METHODS

In this placebo-controlled, double-blind, and balanced crossover study, 40 healthy individuals were divided in low- (n = 21) and high (n = 19)-caffeine consumers, according to their daily caffeine consumption. All participants ingested either caffeine (4 mg/kg) or placebo, and IOP and OPP were measured after 30, 60, and 90 min of ingesting caffeine or placebo. Subjective feelings of arousal were also obtained.

RESULTS

Caffeine induced an acute IOP rise (p < 0.001, ƞ_p² = 0.408), whereas habitual caffeine demonstrated a mediating effect on the IOP changes induced by caffeine intake, with high-caffeine consumers showing a less accentuated IOP rise in comparison to low-caffeine consumers. The greatest IOP change induced by caffeine intake was reached after 90 min from capsule ingestion, being more accentuated for the low-caffeine consumers (+ 3.4 mmHg) than for the high-caffeine consumers (+ 1.2 mmHg). Consequently, the participants reported higher levels of perceived arousal after ingesting caffeine in comparison to placebo (p = 0.002, ƞ_p² = 0.222); however, similar responses were given by high- and low-caffeine consumers (p = 0.256). Our data did not reveal any effect of caffeine consumption on OPP (p = 0.304).

CONCLUSIONS

These results suggest that IOP responsiveness to caffeine ingestion is subject to tolerance, which could have important implication in the management of glaucoma. This finding may be due to alterations in the adenosine receptor system caused by chronic caffeine consumption. Future studies are needed to assess if these findings are also applicable to patients with glaucoma.

Caffeine and the eye

Caffeine, a popular psychostimulant that acts as an adenosine receptor antagonist, is the most widely used drug in history, consumed daily by people worldwide. Knowledge of the physiological and pathological effects of caffeine is crucial in improving public health because of its widespread use. We provide a summary of the current evidence on the effect of caffeine on the eye. Most of the research conducted to date is in relation to cataract and glaucoma, two of the most common eye diseases among the elderly.

The Role of Diet in Glaucoma: A Review of the Current Evidence

Intraocular pressure (IOP) reduction by medications, laser, or surgery remains the mainstay of treatment in glaucoma. However, the role of complementary and alternative medicine (CAM) in glaucoma has received great interest from both patients and ophthalmologists. Previous evidence suggests that diet, a major domain of CAM, can influence an individual's IOP level. Furthermore, certain dietary components have been linked to the incidence and progression of glaucoma. In this review, we aim to provide a summary of the current evidence regarding the role of obesity, certain dietary components, and dietary supplements in glaucoma.

Dietary factors and the risk of glaucoma: a review

Glaucoma is an optic neuropathy characterized by a progressive typical pattern of optic neurodegeneration and visual field loss. A relatively high proportion of glauctomatous individuals admit to interest in dietary modification in an attempt to manage their disease. Heavy caffeine consumption appears to have a transient effect on increasing intraocular pressure (IOP). This effect may be clinically insignificant for nonglaucomatous individuals, but the association warrants clinical consideration in those with the disease. Studies investigating the relationship between self-reported antioxidant intake and risk of glaucomatous disease have reported conflicting results. Preliminary studies investigating the relationship between self-reported glaucoma diagnosis and consumption of the oxidants calcium and iron suggest a possible relationship indicating increased risk of the disease with increased consumption of these dietary factors. Initial reports in the literature suggest a potential role for dietary modification in the treatment of glaucomatous optic neuropathy. Further study, with randomized controlled trials, may be necessary to further characterize these relationships.

The effect of caffeine on choroidal thickness in young healthy subjects

BACKGROUND

To investigate the effect of oral caffeine intake on choroidal thickness using optical coherence tomography (OCT).

METHODS

Eighteen otherwise healthy caffeine users and 18 controls were enrolled. All participants underwent OCT scanning with high-speed and resolution spectral-domain OCT device (3D OCT 2000, Topcon, Japan) at baseline, and 1 and 3 h following 200-mg oral caffeine intake in the study and after oral placebo in the control group. The measurements were taken in the morning (10-12 am) to avoid diurnal fluctuation.

RESULTS

The median choroidal thickness at the fovea prior to oral caffeine intake was 337.00 (IQR 83.75) μm, which decreased to 311.00 (IQR 79.25) μm at 1 h and 311.00 (IQR 75.00) μm at 3 h following oral caffeine intake (p = 0.001, 0.002, respectively). The median choroidal thickness was also significantly decreased following oral caffeine intake at other five extrafoveal points (p < 0.05 for all). The difference in choroidal thickness was not statistically significant between 1 and 3 h of caffeine intake at all six points. In the control group, the median baseline choroidal thickness at the fovea was 330.00 (IQR 88.75) μm, which was 330.50 (IQR 80.75) μm at 1 h and 330.50 (IQR 90.75) μm at 3 h (p = 0.552, 0.704, respectively).

CONCLUSIONS

Caffeine causes a significant decrease in choroidal thickness following oral intake. This decrease might be a result of reduced ocular blood flow due to its vasoconstrictive effect.

The effect of caffeine on retinal vessel diameter in young healthy subjects

PURPOSE

To investigate the effect of caffeine on retinal vessel diameter before and during flicker light stimulation in young healthy subjects.

METHODS

Seventeen healthy subjects (mean age: 29.6 ± 3.73 years, range: 22-35 years) were included in this study. The diameter of retinal vessels was measured continuously with the retinal vessel analyzer (RVA) before and 1 hr after 200 mg oral caffeine intake. After baseline assessment, a green luminance flicker of 20-second duration was applied to stimulate retinal activity. The diameter of a segment of an arteriole and of a venule were measured during stimulation and 80 second after cessation of the stimulus. Flicker stimulation and 80-second measurement interval were carried out three times. Blood pressure parameters, systemic mean arterial pressure (MAP), ocular perfusion pressure (OPP) and intraocular pressure (IOP) were obtained before and after oral caffeine intake.

RESULTS

The mean diameter of the arterioles at baseline before caffeine intake was 123.30 ± 14.0 μm (arithmetic mean standard deviation) and after caffeine 117.30 ± 13.0 μm which was significantly different (p=0.004). The mean diameter of the venules at baseline before caffeine intake was 147.60 ± 19.5 μm and after caffeine 137.73 ± 19.9 μm which was significantly different (p = 0.005). The mean diameter of the arterioles during flicker light stimulation before caffeine intake was 126.65 ± 13.24 μm and after caffeine intake 121.59 ± 12.12 μm (p = 0.012). The mean diameter of the venules during flicker light stimulation before caffeine intake was 151.87 ± 18.63 μm and after caffeine intake was 145.14 ± 19.82 μm (p = 0.027). The flicker response of the arterioles increased from 2.8% before caffeine to 3.8% after caffeine intake (p = 0.010). The flicker response of the venules increased from 3.4% before caffeine to 5.5% after caffeine intake (p = 0.0001). Baseline diameters and diameters during flicker light stimulation after caffeine intake showed a significant negative correlation to the MAP for the arterioles (baseline: r = -0.338, p = 0.049 and flicker: r = -0.345, p = 0.046) and the venules (baseline: r = -0.496, p = 0.003 and flicker: r =-0.479, p = 0.004).

CONCLUSIONS

The present study showed a significant vasoconstrictory response of the retinal vessels 1 hr after caffeine intake in young healthy subjects. Retinal vessel diameter changes were negatively correlated with MAP after caffeine consumption. These effects seem to be elicited by an autoregulatory response of the retinal vessels to the increased blood pressure changes after caffeine.

The Relationship between caffeine and coffee consumption and exfoliation glaucoma or glaucoma suspect: a prospective study in two cohorts

PURPOSE

We examined the association between caffeine and caffeinated beverage consumption in relation to the risk of exfoliation glaucoma or exfoliation glaucoma suspect (EG/EGS).

METHODS

We followed 78,977 women from the Nurses' Health Study (NHS) and 41,202 men from the Health Professionals Follow-up Study (HPFS) who were at least 40 years of age, did not have glaucoma, and reported undergoing eye examinations from 1980 (NHS) or 1986 (HPFS) to 2008. Information on consumption of caffeine-containing beverages and potential confounders were repeatedly ascertained in validated follow-up questionnaires. Confirmation with medical record review revealed 360 incident EG/EGS cases. Multivariate rate ratios (RRs) for EG/EGS were calculated in each cohort and then pooled using meta-analytic techniques.

RESULTS

Compared with participants whose cumulatively updated total caffeine consumption was <125 mg/day, participants who consumed ≥ 500 mg/day had a trend toward increased risk of EG/EGS that was not statistically significant (RR = 1.43; 95% confidence interval [CI], 0.98-2.08); P trend = 0.06). Compared to abstainers, those who drank ≥ 3 cups of caffeinated coffee daily were at increased risk of EG/EGS (RR = 1.66; 95% CI, 1.09-2.54; P trend = 0.02). These results were not materially altered after adjustment for total fluid intake. Associations were stronger among women with a family history of glaucoma (P interaction = 0.06 for coffee; P interaction = 0.03 for caffeine). We did not find associations with consumption of other caffeinated products (caffeinated soda, caffeinated tea, decaffeinated coffee or chocolate) and risk of EG/EGS (P trend ≥ 0.31).

CONCLUSIONS

We observed a positive association between heavier coffee consumption with risk of EG/EGS in this large prospective study.

A new strategy for diurnal intraocular pressure curve

PURPOSE

To investigate whether there is agreement between intraocular pressure (IOP) readings in the supine position at 6 am upon awaking (before getting out of bed) and the IOP at 8 am, also measured in supine position after remaining 30 minutes in this position.

METHODS

In a sample of 50 eyes of 50 patients (normal, glaucoma suspect, and glaucoma patients), 6 am IOP was measured in the supine position upon awaking and before getting up, while 8 am IOP was measured on the same day, also in the supine position after 30 minutes in this position.

RESULTS

The IOP values at 6 am were mean 16.06±3 mmHg; median 15.5 mmHg (range 10-25.5 mmHg). For the 8 am readings, the average was 15.94±4 mmHg and the median 15 mmHg (range 10-25.5 mmHg). The difference between mean 6 and 8 am IOPs was 0.13±0.9 mmHg (confidence interval -0.14 to 0.40). Pearson correlation coefficient between the 6 and 8 am IOPs for the total sample was r=0.97 (p<0.05). There were no significant differences in behavior regarding eyes with high IOP as compared to normal IOP eyes (repeated-measure analysis of variance, p=0.72).

CONCLUSIONS

The 8 am IOP readings obtained in the supine position and under the conditions described were equivalent to 6 am IOP readings (as the first measure of the diurnal pressure curve [DPC]). This new strategy for DPC will make it a widely used tool in daily practice since it spares the need for hospitalization or home measurements.

Effects of caffeinated coffee consumption on intraocular pressure, ocular perfusion pressure, and ocular pulse amplitude: a randomized controlled trial

PURPOSE

To examine the effects of caffeinated coffee consumption on intraocular pressure (IOP), ocular perfusion pressure (OPP), and ocular pulse amplitude (OPA) in those with or at risk for primary open-angle glaucoma (POAG).

METHODS

We conducted a prospective, double-masked, crossover, randomized controlled trial with 106 subjects: 22 with high tension POAG, 18 with normal tension POAG, 20 with ocular hypertension, 21 POAG suspects, and 25 healthy participants. Subjects ingested either 237 ml of caffeinated (182 mg caffeine) or decaffeinated (4 mg caffeine) coffee for the first visit and the alternate beverage for the second visit. Blood pressure (BP) and pascal dynamic contour tonometer measurements of IOP, OPA, and heart rate were measured before and at 60 and 90 min after coffee ingestion per visit. OPP was calculated from BP and IOP measurements. Results were analysed using paired t-tests. Multivariable models assessed determinants of IOP, OPP, and OPA changes.

RESULTS

There were no significant differences in baseline IOP, OPP, and OPA between the caffeinated and decaffeinated visits. After caffeinated as compared with decaffeinated coffee ingestion, mean mm Hg changes (± SD) in IOP, OPP, and OPA were as follows: 0.99 (± 1.52, P<0.0001), 1.57 (± 6.40, P=0.0129), and 0.23 (± 0.52, P<0.0001) at 60 min, respectively; and 1.06 (± 1.67, P<0.0001), 1.26 (± 6.23, P=0.0398), and 0.18 (± 0.52, P=0.0006) at 90 min, respectively. Regression analyses revealed sporadic and inconsistent associations with IOP, OPP, and OPA changes.

CONCLUSION

Consuming one cup of caffeinated coffee (182 mg caffeine) statistically increases, but likely does not clinically impact, IOP and OPP in those with or at risk for POAG.

Alternative therapy in glaucoma management: is there any role?

Glaucoma is one of the leading causes of blindness worldwide. Various randomized controlled clinical trials have shown that lowering intraocular pressure (IOP) does reduce progression of primary open-angle glaucoma. However, there is lots of interest in nonpharmacological options that includes lifestyle adjustment and alternative and complementary therapy (ACT). At least 5% glaucoma population uses ACT. Various lifestyle activities like exercise and alcohol can reduce IOP by 1 to 2 mm Hg but would have small effect on glaucoma. The psychological stress can increase IOP. Hypothetically and few studies do show neuroprotective effect (or effect on ocular blood flow) of alcohol, Gingko biloba, bilberry, but the current evidence is weak for its routine use. We must also remember the side effects of 'medications' (e.g., marijuana, alcohol) before promoting as remedy for glaucoma. In current armamentarium of glaucoma management, ACT cannot substitute the conventional treatment available to lower IOP.

The effect of caffeine on intraocular pressure: a systematic review and meta-analysis

BACKGROUND

Caffeine is widely consumed, and its effect on intraocular pressure (IOP) has been reported in conflicting data. The aim of this meta-analysis was to quantitatively summarize the effect of caffeine on IOP in normal individuals and in patients with glaucoma or ocular hypertension (OHT).

METHODS

A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify pertinent randomized controlled trials (RCTs) from the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed and EMBASE. A systematic review and meta-analysis was performed. IOP at 0.5 hour (h), 1 h and 1.5 h after caffeine ingestion was the main outcome measurement.

RESULTS

Six RCTs (two parallel-designed and four crossover-designed) evaluating 144 participants fulfilled inclusion criteria. The risk of bias for these studies was uncertain. Among the participants, 103 were normal individuals and 41 were patients with glaucoma or OHT. In normal individuals, the IOPs measured at 0.5 h, 1 h and 1.5 h post-intervention were not affected by ingestion of caffeine. The weighted mean difference (WMD) with 95% confidence intervals (95%CI) for each measurement point were -0.740 (-2.454, 0.974), 0.522 (-0.568, 1.613) and 0.580 (-1.524, 2.684). However, in patients with glaucoma or OHT, IOP increased at each measurement point, with the WMD and 95%CI being 0.347 (0.078, 0.616), 2.395 (1.741,3.049) and 1.998 (1.522,2.474) respectively. No publication bias was detected by either Begg's or Egger's test.

CONCLUSION

Available evidences showed that caffeine had different effects on IOP in different groups of individuals. For normal individuals, IOP was not changed by ingestion of caffeine, while for patients with glaucoma or OHT, IOP increased significantly. More high-quality RCTs are warranted to confirm this. The mechanisms underlying this phenomenon and the clinical significance are to be explored.

The effect of caffeine on retrobulbar hemodynamics

BACKGROUND

To investigate the acute effect of caffeine on intraocular pressure and retrobulbar blood flow velocity.

METHODS

In this randomized, double-masked, placebo-controlled, prospective study, we examined the effects of single 300-mg oral administration of caffeine on retrobulbar arteries' hemodynamics by using color Doppler ultrasonography imaging in healthy human volunteers. The subjects were divided into two groups; group 1 received a 300-mg caffeine tablet and group 2 received placebo. Measurements were obtained in two eyes at baseline, and 1 hr after acute ingestion of caffeine. Blood pressure, pulse rate, and intraocular pressure were monitored.

RESULTS

When compared with placebo, no significant change in mean blood pressure or intraocular pressure was observed after administration of caffeine. No significant differences were detected in the peak systolic and end diastolic velocities of retrobulbar arteries, compared with baseline values. Resistive index of ophthalmic, central retinal, and short posterior nasal ciliary artery were significantly increased after oral application of caffeine in group 1 (p<0.05).

CONCLUSION

The vascular resistance of the retrobulbar vessels appears to be altered by caffeine consumption. Further studies are needed to investigate the effects of caffeine on hemodynamics in patients with glaucoma.

Caffeine consumption and the risk of primary open-angle glaucoma: a prospective cohort study

PURPOSE

To investigate whether caffeine, which transiently increases intraocular pressure (IOP) is associated with the risk of primary open-angle glaucoma (POAG).

METHODS

A total of 79,120 women from 1980 to 2004 and 42,052 men from 1986 to 2004, who were 40+ years of age, did not have POAG, and reported undergoing eye examinations, were observed. Information on caffeine consumption, potential confounders, and POAG diagnoses were repeatedly updated in validated follow-up questionnaires. One thousand eleven incident POAG cases were confirmed with medical record review. Cohort-specific and pooled analyses across cohorts were conducted to calculate multivariate rate ratios (RRs).

RESULTS

Compared with daily intake of less than 150 mg, the pooled multivariate RRs were 1.05 (95% confidence interval [CI], 0.89-1.25) for consumption of 150 to 299 mg/d, 1.19 (95% CI, 0.99-1.43) for 300 to 449 mg/d, 1.13 (95% CI, 0.89-1.43) for 450 to 559 mg/d, and 1.17 (95% CI, 0.90-1.53) for 600+ mg/d (P for trend = 0.11). However, for consumption of five or more cups of caffeinated coffee daily, the RR was 1.61 (95% CI, 1.00-2.59; P for trend = 0.02); tea or caffeinated cola intake were not associated with risk. Greater caffeine intake was more adversely associated with POAG among those reporting a family history of glaucoma, particularly in relation to POAG with elevated IOP (P for trend = 0.0009; P interaction = 0.04).

CONCLUSIONS

Overall caffeine intake was not associated with increased risk of POAG. However, in secondary analyses, caffeine appeared to elevate risk of high-tension POAG among those with a family history of glaucoma. This result may be due to chance, but warrants further study.

Effects of Caffeine on Intraocular Pressure

PURPOSE

To examine the relationship between coffee and caffeine intakes and intraocular pressure (IOP).

MATERIALS AND METHODS

The Blue Mountains Eye Study examined 3654 participants aged 49+ years in an area west of Sydney, Australia. A detailed medical history questionnaire included average daily intakes of coffee and tea. The eye examination included Goldmann applanation tonometry and automated perimetry. Participants using glaucoma medications or who had previous cataract or glaucoma surgery or signs of pigmentary glaucoma/pigment dispersion, were excluded. Mean and maximum IOP calculations were used.

RESULTS

Participants with open-angle glaucoma (OAG) who reported regular coffee drinking had significantly higher mean IOP (19.63 mm Hg) than participants who said that they did not drink coffee (16.84 mm Hg), after multivariate adjustment, P = 0.03. Participants consuming > or = 200 mg caffeine per day had higher mean IOP (19.47 mm Hg) than those consuming < 200 mg caffeine per day (17.11 mm Hg), after adjusting for age, sex, and systolic blood pressure (SBP), P = 0.06. This association did not reach statistical significance after multivariate adjustment. No association between coffee or caffeine consumption and higher IOP was found in participants with ocular hypertension (OH) and those without open-angle glaucoma.

CONCLUSIONS

In participants with open-angle glaucoma, this study identified a positive cross-sectional association between coffee consumption/higher caffeine intakes and elevated intraocular pressure.