Incidence of open-angle glaucoma: the Barbados Eye Studies. The Barbados Eye Studies Group. Factors for glaucoma progression and the effect of treatment: the early manifest glaucoma trial. [1,3,7-trimethylxanthine. Effects on circadian aqueous humor dynamics in probands]. The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma. Effects of caffeine on microcirculation of the human ocular fundus. Effects of caffeinated coffee on intraocular pressure. [Timolol: long-term results, tolerance test and early-morning measurements (author's transl)]. The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry The Ocular Hypertension Treatment Study: topical medication delays or prevents primary open-angle glaucoma in African American individuals. The effect of caffeine on the human macular circulation. The Effect of Caffeine on Retrobulbar Hemodynamics Relation between corneal thickness and intraocular pressure measurement by noncontact and applanation tonometry Effect of Coffee Consumption on Intraocular Pressure Interaction of timolol and caffeine on intraocular pressure. Caffeine has no clinically significant effect on aqueous humor flow in the normal human eye. The effect of caffeine on intraocular pressure in glaucoma patients.
OBJECTIVE To measure the 4-year risk of open-angle glaucoma ( OAG ) in a black population . DESIGN Population -based cohort study with 4 years of follow-up . SETTING Simple r and om sample of residents of Barbados , West Indies , aged 40 years or older . PARTICIPANTS A total of 3427 members of the cohort ( 85 % of those eligible ) . MAIN OUTCOME MEASURE Development of glaucoma visual field defects and optic disc damage , confirmed by automated perimetry , independent fundus photographic gradings , and st and ardized ophthalmologic examinations . RESULTS The 4-year risk of OAG in black participants was 2.2 % ( 95 % confidence interval , 1.7%-2.8 % ) , based on 67 newly developed cases of OAG . Incidence rates increased from 1.2 % at ages 40 to 49 years to 4.2 % at ages of 70 years or more , tending to be higher in men than women ( 2.7 % vs 1.9 % ) . About half of the incident cases were undiagnosed previously , and the rest were receiving OAG treatment . Of the 67 new cases of OAG , 32 had intraocular pressure of 21 mm Hg or less at baseline ( 1.2 % incidence ) and 35 had higher pressures ( 9 % incidence ) . Risk was highest among persons classified as having suspect OAG at baseline ( 26.1 % ) , followed by those with ocular hypertension ( 4.9 % ) and lowest in the remaining population ( 0.8 % ) . CONCLUSIONS This longitudinal study provides new information on OAG risk , as well as the first incidence measurement in a black population . Although intraocular pressure increased risk , about half of the new cases had baseline pressures of 21 mm Hg or less . Results substantiate the high OAG risk in the population of African origin , especially in older adults ; the relative role of intraocular pressure ; and the considerable underdetection of new disease after 4 years of follow-up OBJECTIVE To assess factors for progression in the Early Manifest Glaucoma Trial ( EMGT ) , including the effect of EMGT treatment . SETTING / PARTICIPANTS Two hundred fifty-five open-angle glaucoma patients r and omized to argon laser trabeculoplasty plus topical betaxolol or no immediate treatment ( 129 treated ; 126 controls ) and followed up every 3 months . METHODS Progression was determined by perimetric and photographic optic disc criteria . Patient-based risk of progression was evaluated using Cox proportional hazard regression models and was expressed as hazard ratios ( HR ) with 95 % confidence intervals ( 95 % CI ) . RESULTS After 6 years , 53 % of patients progressed . In multivariate analyses , progression risk was halved by treatment ( HR = 0.50 ; 95 % CI , 0.35 - 0.71 ) . Predictive baseline factors were higher intraocular pressure ( IOP ) ( ie , the higher the baseline IOP , the higher the risk ) , exfoliation , and having both eyes eligible ( each of the latter 2 factors doubled the risk ) , as well as worse mean deviation and older age . Progression risk decreased by about 10 % with each millimeter of mercury of IOP reduction from baseline to the first follow-up visit ( HR = 0.90 per millimeter of mercury decrease ; 95 % CI , 0.86 - 0.94 ) . The first IOP at that visit ( 3 months ' follow-up ) was also related to progression ( HR = 1.11 per millimeter of mercury higher ; 95 % CI , 1.06 - 1.17 ) , as was the mean IOP at follow-up ( HR = 1.13 per millimeter of mercury higher ; 95 % CI , 1.07 - 1.19 ) . The percent of patient follow-up visits with disc hemorrhages was also related to progression ( HR = 1.02 per percent higher ; 95 % CI , 1.01 - 1.03 ) . No other factors were identified . CONCLUSIONS Patients treated in the EMGT had half of the progression risk of control patients . The magnitude of initial IOP reduction was a major factor influencing outcome . Progression was also increased with higher baseline IOP , exfoliation , bilateral disease , worse mean deviation , and older age , as well as frequent disc hemorrhages during follow-up . Each higher ( or lower ) millimeter of mercury of IOP on follow-up was associated with an approximate 10 % increased ( or decreased ) risk of progression Anterior chamber fluorophotometry ( Fluorotron Master II , Coherent , Palo Alto , Calif. ) was used to investigate the influence of 1,3,7-trimethylxanthin on the circadian rhythm of aqueous humor secretion in two age- , race- and sex-matched groups of healthy volunteers . In ten males and ten females ( mean age 27 years ) , aqueous humor secretion was measured over 24 h at : 0800 , 0900 , 1000 - 1400 , 1500 , 1600 - 2000 , 2100 , 2200 - 0200 , 0300 , and 0400 hours . Flow was calculated using the Yablonsky protocol of Fluorotron Master II . In group I all volunteers received about 800 mg trimethylxanthin in the form of caffeinated coffee between 2200 and 2300 hours . In group II volunteers went to sleep at 2300 hours . Sleep was only interrupted for measurements . During the daytime the mean aqueous humor flow was the same in both groups ( 0800 to 2200 hours ) ( Student 's t-test ) : Group I ( n = 10 ) RA 2.27 + /- 0.70 microliters/min LA 2.25 + /- 0.74 microliters/min Group II ( n = 10 ) RA 2.23 + /- 0.73 microliters/min LA 2.06 + /- 0.64 microliters/min During the night the mean aqueous humor flow decreased in both groups ( 0200 to 0400 hours ) : Group I : RA 1.99 + /- 0.74 microliters/min delta flow = -12 % LA 1.93 + /- 0.75 microliters/min Group II : RA 0.97 + /- 0.50 microliters/min delta flow = -56 % LA 0.97 + /- 0.48 microliters/min The difference between groups was statistically significant ( P = 0.01 , t-test for unpaired sample s ) . There was no significant change in mean aqueous humor flow between the daytime vs night in group I ( P < 0.5 ) . ( ABSTRACT TRUNCATED AT 250 WORDS BACKGROUND The Ocular Hypertension Treatment Study ( OHTS ) has shown that topical ocular hypotensive medication is effective in delaying or preventing the onset of primary open-angle glaucoma ( POAG ) in individuals with elevated intraocular pressure ( ocular hypertension ) and no evidence of glaucomatous damage . OBJECTIVE To describe baseline demographic and clinical factors that predict which participants in the OHTS developed POAG . METHODS Baseline demographic and clinical data were collected prior to r and omization except for corneal thickness measurements , which were performed during follow-up . Proportional hazards models were used to identify factors that predicted which participants in the OHTS developed POAG . RESULTS In univariate analyses , baseline factors that predicted the development of POAG included older age , race ( African American ) , sex ( male ) , larger vertical cup-disc ratio , larger horizontal cup-disc ratio , higher intraocular pressure , greater Humphrey visual field pattern st and ard deviation , heart disease , and thinner central corneal measurement . In multivariate analyses , baseline factors that predicted the development of POAG included older age , larger vertical or horizontal cup-disc ratio , higher intraocular pressure , greater pattern st and ard deviation , and thinner central corneal measurement . CONCLUSIONS Baseline age , vertical and horizontal cup-disc ratio , pattern st and ard deviation , and intraocular pressure were good predictors for the onset of POAG in the OHTS . Central corneal thickness was found to be a powerful predictor for the development of POAG PURPOSE To determine the effect of caffeine on microcirculation in the human ocular fundus . METHODS The microcirculation in the ocular fundus of 10 healthy volunteers ( 10 eyes ) was studied using a laser speckle tissue circulation analyzer . Caffeine or placebo ( 100 mg ) was administered orally in a double-masked manner . Square blur rate ( SBR ) , a quantitative index of blood flow velocity , was measured in a temporal site of the optic nerve head ( ONH ) free of surface vessels and in a middle site of the choroid-retina between the ONH and macula . Intraocular pressure ( IOP ) , blood pressure ( BP ) , pulse rate ( PR ) , and central critical fusion frequency ( CFF ) were also measured . These parameters were measured before and for 2 hours after administration . The area under curve ( AUC ) of SBR was calculated for each area . Ocular perfusion pressure ( OPP ) was also calculated from BP and IOP . RESULTS The time-course of change in SBR value showed much individual difference . Caffeine decreased the AUC of SBR in the ONH ( P = .0218 ) as well as in the choroid-retina ( P = .0469 ) significantly . IOP , mean BP , PR , OPP , and central CFF did not change significantly . CONCLUSIONS These results suggest that caffeine may increase blood vessel resistance and decrease blood flow in the human ONH and choroid-retina This study examined the effects of caffeinated coffee on the  intraocular pressure of nonglaucomatous subjects . Subjects were r and omly assigned to receive each of three treatments : caffeinated coffee , hot water , and no fluid . All subjects were given the three treatment conditions over 3 days . The study revealed that intraocular pressure after ingesting caffeinated coffee was significantly higher than after receiving the other two treatment conditions . It was further found that increased intraocular pressure was maintained at significant levels over a 3-hour period . No significant changes were found in the pulse rate , and findings on blood pressure were inconclusive In a study lasting 16 months , Timolol was tested on 57 eyes of a group of selected patients with open-angle glaucoma . Patients whose IOP could not be stabilized with the 0.25 % solution were treated with 0.5 % drops twice a day . In five separate cases , where regulation was inadequate , pilocarpine 2 % twice a day was prescribed in addition . At the end of 16 months ' treatment pressure had been lowered to a statistically highly significant degree in 66 % of the patients . While the degree of regulation in the remainder was not statistically sifnificant , most of them were adequately stabilized . Further , following stabilization with Timolol , 42 % of the patients were subjected to tolerance tests under constant conditions ( darkness test , water test , coffee and tea tolerance ) and their 6.00 a.m.values were measured . While good pressure levels were recorded in the tolerance tests , the early-morning IOP rose to critical threshold levels in some patients . However , during the entire period of observation visual fields and optic disk findings remained unaltered in all cases . Only a few cases were subjective and /or objective side-effects seen . Ten percent of those patients who had been treated previously required new glasses ( + 0,5 to + 1 D over the previous correction ) Aims : To evaluate the influence of central corneal thickness ( CCT ) on intraocular pressure ( IOP ) measurements made with the Goldmann applanation tonometer ( GAT ) , Tono-Pen XL , ocular blood flow tonograph ( OBF ) , and Canon TX-10 non-contact tonometer ( NCT ) . Methods : CCT was recorded for either eye ( r and omly selected ) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital . For each of the selected eyes , IOP was measured with the GAT ( two observers ) , Tono-Pen , OBF , and NCT in a r and omised order . The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis . Results : A significant association between measured IOP and CCT was found with each instrument . The change in measured IOP for a 10 μm increase in CCT was 0.28 , 0.31 , 0.38 , and 0.46 for the GAT , Tono-Pen , OBF , and NCT , respectively ( all p⩽0.05 ) . There was a significant association between the NCT/GAT differences and CCT , with a tendency of NCT to overestimate GAT in eyes with thicker corneas . There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age , with a tendency of GAT and OBF to overestimate the Tono-Pen in eyes of older subjects . Conclusion : IOP measurement by all four methods is affected by CCT . The NCT is affected by CCT significantly more than the GAT . Subject age has a differential effect on the IOP measurements made by the GAT and OBF compared to the Tono-Pen BACKGROUND The prevalence of glaucoma is higher in African American individuals than in white individuals . OBJECTIVE To report the safety and efficacy of topical ocular hypotensive medication in delaying or preventing the onset of primary open-angle glaucoma ( POAG ) among African American participants in the Ocular Hypertension Treatment Study . METHODS Eligibility criteria included age between 40 and 80 years , intraocular pressure between 24 and 32 mm Hg in one eye and between 21 and 32 mm Hg in the other eye , and no evidence of glaucomatous structural or functional damage by st and ard clinical measures . Participants were r and omized to either the observation group or medication group . Of the 1636 participants r and omized , 408 were self-identified as African American . MAIN OUTCOME MEASURE The primary outcome was the development of reproducible visual field abnormality and /or reproducible optic disc deterioration attributed to POAG . RESULTS Among African American participants , 17 ( 8.4 % ) of 203 in the medication group developed POAG during the study ( median follow-up , 78 months ) compared with 33 ( 16.1 % ) of 205 participants in the observation group ( hazard ratio , 0.50 ; 95 % confidence interval , 0.28 - 0.90 ; P = .02 ) . CONCLUSION Topical ocular hypotensive therapy is effective in delaying or preventing the onset of POAG in African American individuals who have ocular hypertension The acute effect of caffeine on the retinal circulation was studied in 14 healthy volunteers using the blue field simulation technique , which provides measurements of the velocity of leukocytes flowing within the macular capillaries . Subjects adjusted the mean velocity ( Vm ) of computer-simulated leukocytes moving on a cathode ray tube screen to match that of their own entoptically perceived leukocytes before and 1 hr after a double-masked , r and omized administration of 200 mg caffeine or placebo . Caffeine produced an average 13 % + /- 5 % ( SEM ) decrease in Vm ( P less than 0.05 ) and a 9 % + /- 3 % increase in diastolic blood pressure ( P less than 0.05 ) . The decrease in Vm and , presumably , blood flow occurring despite the increased diastolic blood pressure probably is attributable to retinal vasoconstriction . This effect may result from caffeine 's known inhibitory effect on adenosine , a potent vasodilator of the retinal vasculature Background : To investigate the acute effect of caffeine on intraocular pressure and retrobulbar blood flow velocity . Methods : In this r and omized , double-masked , placebo-controlled , prospect i ve 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 Purpose : To assess whether there is a significant difference in intraocular pressure ( IOP ) measurements between noncontact and applanation methods and if so , whether the difference is correlated with corneal thickness . Setting : Iş&igr;k Eye Clinic , Ankara , Turkey . Methods : This prospect i ve study comprised 120 eyes of 60 r and omly selected patients .  Noncontact tonometry , applanation tonometry , and pachymetry were performed in each eye . The results were compared and an analysis was performed to determine whether there was a correlation between the differences in IOP measurements and corneal thickness in the entire group and in subgroups composed of the halves and quarters of the group . Results : The mean IOP in the entire group was 20.38 mm Hg ± 4.97 ( SD ) with the noncontact tonometer and 18.84 ± 4.47 mm Hg with the Goldmann applanation tonometer . The difference between the measurements with the noncontact method and those with the applanation method was statistically significant ( P < .01 ) except in cases having a corneal thickness between 513 & mgr;m and 539 & mgr;m ( P gt ; .01 ) . There was a positive correlation between corneal thickness and the difference in measurements by noncontact and applanation tonometry , and the magnitude of correlation was greater in cases with thicker corneas . Conclusion : The reliability of tonometers decreased with increasing corneal thickness , in which case higher readings were found , especially with the noncontact tonometer BACKGROUND : Many ophthalmologists instruct patients with glaucoma to avoid coffee , although data supporting this practice are insufficient . OBJECTIVE : To estimate the effect of drinking coffee on intraocular pressure ( IOP ) . METHODS : In this crossover study , the effect of the consumption of regular ( 180 mg caffeine in 200 mL beverage ) and decaffeinated coffee ( 3.6 mg caffeine in 200 mL beverage ) was compared in patients with normotensive glaucoma ( n = 6 ) or ocular hypertension ( n = 22 ) .  IOP was monitored in both groups at 30 , 60 , and 90 minutes after coffee ingestion . RESULTS : In patients with normotensive glaucoma who drank regular coffee , the mean ± SD changes in IOP at 30 , 60 , and 90 minutes were 0.9 ± 0.5 , 3.6 ± 1.1 , and 2.3 ± 0.66 mm Hg , respectively ; in those who drank decaffeinated coffee , they were 0.75 ± 0.36 , 0.70 ± 0.4 , and 0.4 ± 0.6 mm Hg , respectively . The corresponding values in patients with ocular hypertension were as follows : after regular coffee , 1.1 ± 0.7 , 3.4 ± 1.0 , and 3.0 ± 2.7 mm Hg ; and after decaffeinated coffee , 0.6 ± 0.4 , 0.9 ± 0.2 , and 0.5 ± 0.5 mm Hg . The difference in the change in IOP from baseline after ingestion of regular versus decaffeinated coffee was statistically significant in each group at 60 and 90 minutes . Subjects who drank regular coffee demonstrated a greater elevation in IOP ; this elevation may be clinical ly significant . CONCLUSIONS : Intake of caffeinated beverage ( ≥180 mg caffeine ) may not be recommended for patients with normotensive glaucoma or ocular hypertension The clinical interaction of 0.5 % timolol maleate and 400 mg of oral caffeine on the  intraocular pressure of 20 normotensive volunteers was studied . Caffeine administration did not significantly alter the reduction in intraocular pressure in timolol treated eyes . An antagonism , however , was observed in the fellow timolol untreated eyes with caffeine . The crossover reduction in intraocular pressure noted in the control group was significantly depressed in the caffeine group . A proposed mechanism for these observations is discussed The effect of orally administered caffeine ( 400 mg ) on aqueous humor flow was studied in 20 normal human subjects . The rate of aqueous flow was measured by fluorophotometry . There was no statistically significant difference in aqueous flow measured hourly from 1 to 4 hours after the administration of caffeine . There also was no statistically significant difference in intraocular pressure ( IOP ) measured 4 hours after caffeine ingestion . The sample size was large enough to have detected a 15 % change in flow , had it occurred The authors investigated the effect of drinking regular coffee on intraocular pressure ( IOP ) using a single-masked r and omized crossover study comparing coffee and herbal tea in 13 glaucoma patients .  Intraocular pressure and blood pressure were monitored before ingestion of coffee or tea and at 30 , 60 , and 90 minutes after ingestion . The mean ( + /- st and ard error of measurement ) change in IOP 30 , 60 , and 90 minutes after ingestion for the coffee drinkers was 0.96 + /- 0.4 , 1.38 + /- 0.53 , and 1.04 + /- 0.37 mmHg , respectively . The mean change in IOP for the tea drinkers 30 , 60 , and 90 minutes after ingestion was 0.85 + /- 0.41 , 0.23 + /- 0.36 , and -0.42 + /- 0.44 mmHg , respectively . There was a statistically significant difference in the change in IOP at 90 minutes when comparing coffee to tea ( P = 0.003 ) and no significant difference for 30 and 60 minutes . Although there was a statistically significant difference in IOP at 90 minutes between coffee and tea drinkers , the change was not clinical ly significant
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 ) .