The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma

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 randomization 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 standard 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 standard deviation, and thinner central corneal measurement.

CONCLUSIONS

Baseline age, vertical and horizontal cup-disc ratio, pattern standard 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.

Relationship between intraocular pressure and primary open angle glaucoma among white and black Americans. The Baltimore Eye Survey

A detailed ocular examination, including perimetry, was conducted on 5308 black and white subjects aged 40 years and older in a population-based prevalence survey in east Baltimore, Md. Repeated, detailed examinations were carried out on selected subjects. Roughly half of all subjects with optic nerve damage from primary open angle glaucoma, regardless of race, were unaware that they had the condition. The average intraocular pressure (IOP) among black patients with glaucoma who were receiving treatment was virtually identical to that in those black patients who were not receiving treatment (median IOP, 20 mm Hg); treated eyes of white patients had a lower IOP than those eyes of white patients who were not receiving treatment (mean [+/- SD] IOP, 18.69 +/- 3.23 mm Hg vs 24.15 +/- 5.23 mm Hg; P less than .001). The risk of glaucomatous optic nerve damage increased with the height of the screening IOP, particularly at levels of 22 to 29 and 30 mm Hg and above (relative rate compared with IOP of 15 mm Hg or lower, 12.8 and 40.1 mm Hg, respectively). More than half of all glaucomatous eyes had a screening IOP below 21 mm Hg, whether these eyes were receiving treatment or not. The IOP in glaucomatous eyes tended to rise on follow-up, in contrast with nonglaucomatous eyes in which the IOP was as likely to rise as to fall. Results confirmed that IOP is an important factor in glaucoma, but did not support the traditional distinction between "normal" and "elevated" pressure, nor its corollaries, "low-tension" glaucoma and "high-tension" glaucoma.

Prevalence of open-angle glaucoma among adults in the United States

OBJECTIVE

To estimate the prevalence and distribution of open-angle glaucoma (OAG) in the United States by age, race/ethnicity, and gender.

METHODS

Summary prevalence estimates of OAG were prepared separately for black, Hispanic, and white subjects in 5-year age intervals starting at 40 years. The estimated rates were based on a meta-analysis of recent population-based studies in the United States, Australia, and Europe. These rates were applied to 2000 US census data and to projected US population figures for 2020 to estimate the number of the US population with OAG.

RESULTS

The overall prevalence of OAG in the US population 40 years and older is estimated to be 1.86% (95% confidence interval, 1.75%-1.96%), with 1.57 million white and 398 000 black persons affected. After applying race-, age-, and gender-specific rates to the US population as determined in the 2000 US census, we estimated that OAG affects 2.22 million US citizens. Owing to the rapidly aging population, the number with OAG will increase by 50% to 3.36 million in 2020. Black subjects had almost 3 times the age-adjusted prevalence of glaucoma than white subjects.

CONCLUSIONS

Open-angle glaucoma affects more than 2 million individuals in the United States. Owing to the rapid aging of the US population, this number will increase to more than 3 million by 2020.

Risk Factors for Incident Open-angle Glaucoma

PURPOSE

To evaluate risk factors for definite open-angle glaucoma (OAG), based on African-descent participants of the Barbados Eye Studies.

DESIGN

Cohort study with 81% to 85% participation over 9 years' follow-up.

PARTICIPANTS

We evaluated 3222 persons at risk, 40 to 84 years old, who did not have definite OAG at baseline.

METHODS

Participants had standardized study visits at baseline and after 4 and 9 years, with structured interviews, blood pressure (BP), and other measurements. The ophthalmic protocol included automated perimetry, applanation tonometry, fundus photography, and comprehensive ophthalmologic examinations for those referred. Central corneal thickness (CCT) was measured in a subset at the 9-year examination. Incidence was estimated by the product-limit approach; relative risk ratios (RRs) with 95% confidence intervals (CIs) were based on Cox regression models with discrete time.

MAIN OUTCOME MEASURE

Nine-year incidence of definite OAG.

RESULTS

Over 9 years, 125 persons developed definite OAG (incidence, 4.4%; 95% CI, 3.7-5.2). Baseline factors influencing risk were age (RR, 1.04; 95% CI, 1.02-1.05 per year); family history of glaucoma (RR, 2.4; 95% CI, 1.3-4.6); higher intraocular pressure (IOP) (RR, 1.12; 95% CI, 1.08-1.16 per mmHg); lower systolic BP (RR, 0.91; 95% CI, 0.84-1.00 per 10 mmHg); and lower ocular systolic, diastolic, and mean perfusion pressures (RR, 0.66; 95% CI, 0.54-0.80 per 10 mmHg higher mean perfusion pressure) (RR, 2.6; 95% CI, 1.4-4.6 for low mean perfusion pressure [<40 mmHg]). Thinner CCT was also associated with OAG incidence (odds ratio, 1.41; 95% CI, 1.01-1.96 per 40 mum lower).

CONCLUSIONS

This is the first report of risk factors for long-term OAG incidence; it is also based on a sizable number of new cases. Incidence was high in this African-descent population, where the established factors of older age, higher IOP, and family history contributed to risk. Additional predictors were vascular factors, including lower systolic BP, and particularly lower ocular perfusion pressures, which more than doubled risk. Thinner CCT was also a factor. These findings indicate a multifactorial etiology of OAG and suggest that similar risk factors apply across populations. Results are relevant for understanding OAG causation and identifying groups at high risk.

Hypertension, perfusion pressure, and primary open-angle glaucoma. A population-based assessment

OBJECTIVE

To evaluate the association of vascular factors with primary open-angle glaucoma (POAG).

DESIGN

A population-based prevalence survey of ocular disease among black and white residents.

SETTING

Communities of east Baltimore, Md.

PARTICIPANTS

A stratified cluster sample of 5308 residents 40 years of age or older.

MAIN OUTCOME MEASURES

Primary open-angle glaucoma as defined by demonstrable glaucomatous optic nerve damage based on visual fields and/or optic disc findings. Intraocular pressure level was not a criterion for diagnosis.

RESULTS

Systolic and diastolic blood pressure showed modest, positive association with POAG. The effect of blood pressure on POAG was modified by age, with a stronger association among older subjects. Lower perfusion pressure (blood pressure-intraocular pressure) was strongly associated with an increased prevalence of POAG, with a sixfold excess for those in the lowest category of perfusion pressure.

CONCLUSION

These results suggest that POAG is associated with an alteration in factors related to ocular blood flow and a breakdown of autoregulation.

The prevalence of glaucoma in a population-based study of Hispanic subjects: Proyecto VER

OBJECTIVE

To determine the prevalence of glaucoma in a population-based sample of Hispanic adults older than 40 years.

METHODS

Using 1990 census data for Arizona, groups of persons living in sections of the city in Nogales and Tucson were randomly selected with a probability proportional to the Hispanic population older than 40 years. We tried to recruit all eligible adults in homes with 1 self-described Hispanic adult. Detailed ocular examinations at a local clinic included visual acuity testing, applanation tonometry, gonioscopy, an optic disc evaluation, and a threshold visual field test. Open-angle glaucoma (OAG) was defined using a proposed international system for prevalence surveys, including threshold visual field defect and optic disc damage. Angle-closure glaucoma was defined as bilateral appositional angle closure, combined with optic nerve damage (judged by field and disc as for OAG).

RESULTS

Examinations were conducted in 72% (4774/6658) of eligible persons, with a 1.97% prevalence (95% confidence interval, 1.58%-2.36%) of OAG (94 persons). The age-specific OAG prevalence increased nonlinearly from 0.50% in those aged 41 to 49 years to 12.63% in those 80 years and older. Angle-closure glaucoma was detected in 5 persons (0.10%). Sex, blood pressure, and cigarette smoking were not significant OAG risk factors. Only 36 (38%) of the 94 persons with OAG were aware of their OAG before the study. Screening results with an intraocular pressure higher than 22 mm Hg (in the eye with a higher pressure) would miss 80% of the OAG cases.

CONCLUSIONS

The prevalence of OAG in Hispanic persons was intermediate between reported values for white and black persons. The prevalence increased more quickly with increasing age than in other ethnic groups. Glaucoma was the leading cause of bilateral blindness.

The prevalence of glaucoma in Chinese residents of Singapore: a cross-sectional population survey of the Tanjong Pagar district

BACKGROUND

Data on prevalence of glaucoma in East Asia are scarce.

OBJECTIVE

To determine the prevalence and clinical characteristics of glaucoma in adult Chinese Singaporeans.

METHODS

A group of 2000 Chinese people, aged 40 to 79 years, were selected from the electoral register of Tanjong Pagar district in Singapore using a disproportionate, stratified, clustered, random-sampling procedure. Glaucoma was diagnosed in people with an excavated optic neuropathy and a reproducible visual field defect or on the basis of severe structural disc abnormality alone, if reliable field results could not be obtained. The diagnosis was also made in blind subjects with raised intraocular pressure or previous glaucoma surgery.

RESULTS

Of 1717 eligible subjects, 1232 were examined, with a response rate of 71.8%. There were 45 cases of glaucoma: 27 were men and 18 were women. The main diagnoses were primary open-angle glaucoma (n = 22 [49%]), primary angle-closure glaucoma (n = 14 [31%]), and secondary glaucoma (n = 7 [16%]). It was not possible to determine the mechanism in 2 (4%).

CONCLUSIONS

The age-standardized prevalence of glaucoma was 3.2% (95% confidence interval, 2.3-4.1) in the population 40 years and older. Glaucoma was the leading cause of blindness. Primary angle-closure glaucoma and secondary glaucoma were the most visually destructive forms of the disease. Our findings suggest current projections of glaucoma prevalence among ethnic Chinese are a substantial underestimate. Arch Ophthalmol. 2000;118:1105-1111

Prevalence of open-angle glaucoma and ocular hypertension in Latinos

OBJECTIVE

To estimate age- and gender-specific prevalences of ocular hypertension and open-angle glaucoma (OAG) in adult Latinos.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

Six thousand three hundred fifty-seven Latinos 40 years and older from 6 census tracts in Los Angeles, California.

METHODS

The study cohort consisted of all self-identified Latinos of primarily Mexican ancestry 40 years and older residing in 6 census tracts in La Puente, California. All participants underwent a complete ophthalmologic examination, including measurement of intraocular pressure (IOP), visual field (VF) testing using an automated field analyzer, and simultaneous stereoscopic fundus photography of the optic disc. Ocular hypertension was defined as IOP of >21 mmHg and the absence of optic disc damage or abnormal VF test results. Open-angle glaucoma was defined as the presence of an open angle and various criteria that included a glaucomatous VF abnormality and/or evidence of glaucomatous optic disc damage in at least one eye.

MAIN OUTCOME MEASURES

Prevalence of open-angle glaucoma and ocular hypertension.

RESULTS

For the 6142 participants who underwent a complete ophthalmologic examination at the clinical center, the prevalence of OAG was 4.74% (95% confidence interval [CI], 4.22%-5.30%). The prevalence of ocular hypertension was 3.56% (95% CI, 3.12%-4.06%). The prevalences of OAG and ocular hypertension were higher in older Latinos than in younger Latinos (P<0.0001). No gender-related differences in prevalences of OAG and ocular hypertension were present. The mean IOP, mean deviation, and mean vertical cup-disc ratio in persons with OAG were 17 mmHg, -9.6 decibels, and 0.6, respectively. Seventy-five percent of Latinos with OAG and 75% of Latinos with ocular hypertension were previously undiagnosed. Further, 17% of Latinos with OAG and 23% of Latinos with ocular hypertension had received treatment for "glaucoma."

CONCLUSION

Our data suggest that the prevalence of OAG is high among Latinos of Mexican ancestry. The higher prevalence of OAG in older Latinos emphasizes the public health importance of providing eye care services for the early diagnosis and management of this condition in Latinos.

A comparison of latanoprost, bimatoprost, and travoprost in patients with elevated intraocular pressure: a 12-week, randomized, masked-evaluator multicenter study

PURPOSE

To Internet Advance publication at ajo.com Feb 13, 2003. compare the intraocular pressure (IOP)-lowering effect and safety of latanoprost, bimatoprost, and travoprost in patients with open-angle glaucoma (OAG) or ocular hypertension (OH).

DESIGN

Interventional study.

METHODS

This 12-week, randomized, parallel-group study was conducted at 45 US sites. Previously treated patients with OAG or OH and an IOP > or =23 mm Hg in one or both eyes after washout received either latanoprost 0.005%, bimatoprost 0.03%, or travoprost 0.004% once daily in the evening. At baseline and after 6 and 12 weeks of therapy, masked evaluators measured IOP in triplicate at 8:00 AM, 12 noon, 4:00 PM, and 8:00 PM, and masked investigators graded conjunctival hyperemia before the 8:00 AM IOP measurement. The primary efficacy outcome measure was change between baseline and Week 12 in the 8:00 AM IOP (time of peak drug effect).

RESULTS

In all, 410 of 411 randomized patients were included in intent-to-treat analyses (latanoprost, 136; bimatoprost, 136; travoprost, 138). Baseline mean 8:00 AM IOP levels were similar (P =.772); by week 12, reductions were observed in all 3 groups (P <.001 for each). Adjusted (ANCOVA) reductions in mean IOP at 8:00 AM were similar (P =.128) as were those at 12 noon, 4:00 PM, and 8:00 PM. Fewer latanoprost-treated patients reported ocular adverse events (P <.001, latanoprost vs bimatoprost), fewer reported hyperemia (P =.001, latanoprost vs bimatoprost), and average hyperemia scores were lower at week 12 (P =.001, latanoprost vs bimatoprost).

CONCLUSIONS

Latanoprost, bimatoprost, and travoprost were comparable in their ability to reduce IOP in OAG and OH patients. Latanoprost exhibited greater ocular tolerability.

Variations in Primary Open-Angle Glaucoma Prevalence by Age, Gender, and Race: A Bayesian Meta-Analysis

PURPOSE

To quantify the variation in primary open-angle glaucoma (OAG) prevalence with age, gender, race, year of publication, and survey methodology.

METHODS

Medline, EMBASE, and PubMed were searched for studies of OAG prevalence. Studies with defined population samplings were sought. Forty-six published observational studies of OAG prevalence (103,567 participants with 2509 cases of OAG) were identified for inclusion in the systematic review and meta-analysis. Data on the number of people and the number of cases of OAG by age, race, and gender were sought for each study. Additional information was obtained regarding whether the definition of glaucoma relied on raised intraocular pressure (IOP) and whether visual field examination was performed routinely on all individuals. Bayesian meta-analysis was used to model the associations between the log odds of OAG and age, race, gender, year of publication, method of visual field testing, and effect of reliance on IOP in the definition of OAG.

RESULTS

Black populations had the highest OAG prevalence at all ages, but the proportional increase in prevalence of OAG with age was highest in white populations. The odds ratio per decade increase in age was 2.05 in white populations (95% credible interval, 1.91 to 2.18), 1.61 (95% credible interval, 1.53 to 1.70) in black populations, and 1.57 (95% credible interval, 1.46 to 1.68) in Asian populations. The average estimated prevalence in those older than 70 years of age was 6% in white populations, 16% in black populations, and 3% in Asian populations. After adjusting for age, race, year of publication, and survey methods, men were 1.37 (95% credible interval, 1.22 to 1.53) times more likely than women to have OAG. The prevalence of OAG was one third lower in studies in which routine visual fields were not assessed and that used an IOP criterion in the definition of glaucoma; this effect was reduced to the null after adjustment for age, racial group, and year of publication.

CONCLUSIONS

Although black populations had the highest prevalence of OAG at all ages, white populations showed the steepest increase in OAG prevalence with age. Men were more likely than women to have OAG.

Viscocanalostomy for open-angle glaucoma in black African patients

PURPOSE

To study the clinical effectiveness of viscocanalostomy in a population of black African patients with open-angle glaucoma that was uncontrolled on medical treatment.

SETTING

Department of Ophthalmology, Medical University of Southern Africa, Medunsa, South Africa.

METHODS

In this prospective study viscocanalostomy was performed in 214 eyes of 157 black African patients with open-angle glaucoma that was poorly controlled by medical therapy. The procedure involves the production of superficial and deep scleral flaps. The deep flap is disserted to the plane of Schlemm's canal. From this plane, an intact window in Descemet's membrane is created by gentle pressure at the level of Schwalbe's line using a cellulose sponge. Aqueous humor diffuses through this window into a subscleral space (lake). Reflection of the inner flap unroofs Schlemm's canal, creating a trough leading to 2 entrances into Schlemm's canal (surgical ostia). A delicate cannula is introduced into the entrance of Schlemm's canal left and right and high-viscosity sodium hyaluronate is gently injected into the canal for 4 to 6 mm. The deeper scleral flap is excised (deep sclerectomy) and the superficial flap is sutured securely using 5, 11-0 polyester fiber (Mersilene) sutures. High-viscosity sodium hyaluronate is then injected into the subscleral lake to act as a physical barrier to fibrinogen migration postoperatively.

RESULTS

Postoperative intraocular pressure (IOP) of 22 mm Hg or less was achieved without medical therapy in 82.7% of eyes. If a beta blocker was added to the cases not achieving 22 mm Hg or less postoperatively, the success rate increased to 89.0%. The average follow-up was 35 months (range 6 to 64 months).

CONCLUSION

Viscocanalostomy produced an encouraging long-term reduction in the IOP of black African patients with glaucoma who would otherwise have had a poor prognosis.

Prevalence and Clinical Characteristics of Glaucoma in Adult Chinese: A Population-Based Study in Liwan District, Guangzhou

PURPOSE

To assess the prevalence and mechanism of glaucoma in adults living in an urban area of southern China.

METHODS

Random clustering sampling was used to identify adults aged 50 years and over in Liwan District, Guangzhou. Glaucoma was diagnosed with the ISGEO (International Society of Geographical and Epidemiological Ophthalmology) classification scheme. All subjects underwent gonioscopy.

RESULTS

In the study, 1504 subjects (75.3% participation rate) were examined, with a crude prevalence of all glaucoma of 3.8% (95% confidence interval [CI], 2.8%-4.8%). Primary open-angle glaucoma (POAG) was found in 2.1% (95% CI, 1.4%-2.8%) and primary angle-closure glaucoma (PACG) in 1.5% (95% CI, 0.8%-2.1%). The prevalence of all glaucoma was significantly higher in older people and men.

CONCLUSIONS

POAG was more common than PACG in this southern Chinese population, with rates similar to those reported in Chinese Singaporeans. The age-adjusted rate of POAG was similar to that found in European-derived populations, but PACG was more common among Chinese, indicating that there is a large burden of glaucoma in the Chinese people.

Family history and risk of primary open angle glaucoma. The Baltimore Eye Survey

OBJECTIVE

Primary open angle glaucoma has been previously associated with a positive family history of glaucoma. We used data from the Baltimore Eye Survey to examine this association.

DESIGN

A population-based prevalence survey identified 161 cases of primary open angle glaucoma among 5308 black and white residents of east Baltimore, Md, who were 40 years of age or older. Family history was ascertained by interview and included all first-degree relatives (parents, siblings, and children).

RESULTS

Age-adjusted associations of primary open angle glaucoma with a history of glaucoma were higher in siblings (odds ratio [OR] = 3.69) than in parents (OR = 2.17) or children (OR = 1.12). Odds ratios were slightly higher in blacks than in whites, and there was evidence of selection bias, with ORs between two and three times higher for those who had prior knowledge of their glaucoma diagnosis than for those who first received their diagnosis by the study examination (history in siblings OR = 4.72 for those with prior knowledge vs 2.77 for those without).

CONCLUSION

Family history is an important risk factor for primary open angle glaucoma, although clinic-based studies are likely to overstate its impact.

Central corneal thickness as a risk factor for advanced glaucoma damage

OBJECTIVE

To determine if central corneal thickness (CCT) is related to the level of glaucoma severity at the initial examination.

METHODS

The initial visit to a glaucoma specialist by consecutive patients with primary open-angle glaucoma from 1997 to 2002 was reviewed retrospectively. Each patient's age, sex, race, family history of glaucoma, number of glaucoma medications, visual acuity, spherical equivalent, intraocular pressure, CCT, visual field data, and vertical and horizontal cup-disc ratios were analyzed.

RESULTS

Three hundred fifty eyes of 190 patients met the inclusion and exclusion criteria. Central corneal thickness was significantly lower in blacks (mean, 537 microm) than in whites (mean, 556 microm). Lower CCT was significantly associated with worsened Advanced Glaucoma Intervention Study score, worsened mean deviation of visual field, increased vertical and horizontal cup-disc ratios, and increased number of glaucoma medications. In multivariate analysis, lower CCT was significantly associated with worsened Advanced Glaucoma Intervention Study score, worsened mean deviation of visual field, and increased vertical and horizontal cup-disc ratios.

CONCLUSIONS

Central corneal thickness is a powerful clinical factor in determining glaucoma severity at the initial examination by a specialist. Measuring CCT may aid the ophthalmologist in identification of glaucoma patients at high risk for progression.

Incident open-angle glaucoma and blood pressure

BACKGROUND

The risk of open-angle glaucoma (OAG) may be related to low blood pressure (BP) relative to intraocular pressure (IOP), ie, to low perfusion pressure (PP). Alternatively, systemic hypertension may increase OAG risk.

OBJECTIVE

To clarify these possible relationships by evaluating hypertension and PP (where PP = BP - IOP) as risk factors for incident OAG in a black population.

DESIGN

Population-based cohort study (85% participation); simple random sample of residents of Barbados, West Indies, aged 40 years and older.

PARTICIPANTS

Two thousand nine hundred eighty-nine black participants at risk; 67 developed OAG after 4 years (2.2% incidence).

MAIN OUTCOME MEASURE

Adjusted relative risk (RR) of OAG from logistic regression analyses.

RESULTS

The 4-year risk increased markedly with baseline IOP. With an IOP less than or equal to 17 mm Hg, incidence was 0.7%, increasing to 18.3% with IOP greater than 25 mm Hg, for a 25-fold increase in RR. However, OAG developed throughout the IOP range and two thirds of incident cases had baseline IOP less than 25 mm Hg. Baseline hypertension was associated with a halving of the RR of OAG (RR, 0.49; 95% confidence interval [CI], 0.29-0.85); the RR also tended to decrease as systolic BP increased (P =.07). Consistent with these findings, a lower baseline PP increased RR (systolic PP <101 mm Hg, 2.6 [95% CI, 1.3-4.9]; diastolic PP <55 mm Hg, 3.2 [95% CI, 1.6-6.6]; mean PP <42 mm Hg, 3.1 [95% CI, 1.6-6.0]).

CONCLUSIONS

As baseline IOP increased, the risk of OAG substantially increased. In contrast, persons with systemic hypertension at baseline had half the RR, suggesting that hypertension does not increase (and may decrease) the 4-year risk of OAG. Lower PP at baseline increased RR approximately 3-fold, a result consistent with the vascular hypothesis of OAG pathogenesis.

24-2 Visual Fields Miss Central Defects Shown on 10-2 Tests in Glaucoma Suspects, Ocular Hypertensives, and Early Glaucoma

PURPOSE

To investigate the prevalence of visual field defects in glaucomatous eyes, glaucoma suspects, and ocular hypertensives with 24-2 and 10-2 visual fields.

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

Patients with or suspected glaucoma tested with 24-2 and 10-2. Patients were classified into 3 groups on the basis of the presence of glaucomatous optic neuropathy (GON) and 24-2 visual field abnormalities: early glaucoma (GON and abnormal visual field, mean deviation >-6 decibels [dB]), glaucoma suspects (GON and normal visual field), and ocular hypertensives (normal disc, normal visual field, and intraocular pressure >22 mmHg). For the classification of visual field abnormalities, 24-2 and 10-2 tests performed on the same visit were analyzed.

MAIN OUTCOME MEASURES

Comparison of the prevalence of abnormal 24-2 versus 10-2 visual field results based on cluster criteria in each diagnostic group.

RESULTS

A total of 775 eyes (497 patients) were evaluated. A total of 364 eyes had early glaucoma, 303 eyes were glaucoma suspects, and 108 eyes were ocular hypertensives. In the glaucoma group, 16 of the 26 eyes (61.5%) classified as normal based on cluster criteria on 24-2 tests were classified as abnormal on 10-2 visual fields. In eyes with suspected glaucoma, 79 of the 200 eyes (39.5%) classified as normal on the 24-2 test were classified as abnormal on 10-2 visual fields. In ocular hypertensive eyes, 28 of the 79 eyes (35.4%) classified as normal on the 24-2 were classified as abnormal on the 10-2. Patients of African descent were more likely to have an abnormal 10-2 result (67.3 vs. 56.8%, P = 0.009).

CONCLUSIONS

Central visual field damage seen on the 10-2 test is often missed with the 24-2 strategy in all groups. This finding has implications for the diagnosis of glaucoma and classification of severity.

Primary open-angle glaucoma in blacks: a review

Glaucoma is one of the leading causes of blindness worldwide. Primary open-angle glaucoma (POAG) is the most prevalent form of glaucoma and has a particularly devastating impact in blacks. In the black American population, POAG prevalence is estimated to be six times as high in certain age groups compared to whites. POAG is more likely to result in irreversible blindness, appears approximately 10 years earlier and progresses more rapidly in blacks than in whites. Racial differences in optic disk parameters have been reported and show that blacks have larger optic disks than whites. This finding is robust and may account for the reported differences in other optic disk parameters. The existence of racial differences in intraocular pressure remains to be demonstrated, as conflicting findings are reported in the literature. Intraocular pressure may actually be underestimated in blacks, perhaps because they have thinner corneas. The prevalence of diabetes and hypertension is higher in blacks than in whites, and although no causal relationship has been established between POAG and each of these systemic diseases, some reports suggest that they often occur together, perhaps through an indirect relationship with intraocular pressure. Compounding the problem, there is evidence that blacks are less responsive to both drug and surgical treatment for POAG. Finally, they often have reduced accessibility to treatment and are less aware of the risks of having POAG. This article provides a comprehensive review of the current knowledge pertaining to POAG in blacks.

The Advanced Glaucoma Intervention Study (AGIS): 4. Comparison of treatment outcomes within race. Seven-year results

OBJECTIVE

The purpose of this report is to present separately for black and white patients with advanced glaucoma 7-year results of two alternative surgical intervention sequences.

DESIGN

A randomized controlled trial.

PARTICIPANTS

A total of 332 black patients (451 eyes), 249 white patients (325 eyes), and 10 patients of other races (13 eyes) participated. Potential follow-up ranged from 4 to 7 years.

INTERVENTION

Eyes were randomly assigned to either an argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) sequence or a trabeculectomy-ALT-trabeculectomy (TAT) sequence. The second and third interventions were offered after failure of the first and second interventions, respectively.

MAIN OUTCOME MEASURES

Average percent of eyes with decrease of visual field (APDVF), average percent of eyes with decrease of visual acuity (APDVA), and average percent of eyes with decrease of vision (APDV) are the outcome measures. Decrease of visual field (DVF) is an increase from baseline of at least 4 points on a glaucoma visual field defect scale ranging from 0 to 20, decrease of visual acuity (DVA) is a decrease from baseline of at least 15 letters (3 lines), and decrease of vision (DV) is the occurrence of either DVF or DVA. The averages are of percent decreases observed at 6-month intervals from the first 6-month visit to the end of the specified observation period.

RESULTS

In both black and white patients throughout 7-year follow-up, the mean decrease in intraocular pressure was greater in eyes assigned to TAT, and the cumulative probability of failure of the first intervention was greater in eyes assigned to ATT. In black patients, APDVF, APDVA, and APDV are less for the ATT sequence than for the TAT sequence throughout the 7 years. In white patients, APDVF also favors the ATT sequence but only for the first year, after which it favors the TAT sequence through the seventh year; APDVA also favors the ATT sequence, but the ATT-TAT difference progressively diminishes over 7 years; and APDV favors ATT over TAT initially, but after 4 years, the advantage switches to and remains with TAT.

CONCLUSIONS

These data support use of the ATT sequence for all black patients. For white patients without life-threatening health problems, the data support use of the TAT sequence.

Type 2 diabetes mellitus and the risk of open-angle glaucoma the Los Angeles Latino Eye Study

PURPOSE

To examine the relationship between type 2 diabetes mellitus (T2DM) and the risk of having open-angle glaucoma (OAG) in an adult Latino population.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Latinos 40 years and older (n = 5894) from 6 census tracts in Los Angeles, California.

METHODS

Participants from the Los Angeles Latino Eye Study (LALES), a large population-based study of self-identified adult Latinos, answered an interviewer-administered questionnaire and underwent a clinical and complete ocular examination, including visual field (VF) testing and stereo fundus photography. A participant was defined as having diabetes mellitus (DM) if she or he had a history of being treated for DM, the participant's glycosylated hemoglobin was measured at 7.0% or higher, or the participant had random blood glucose of 200 mg% or higher. Type 2 DM was defined if the participant was 30 years or older when diagnosed with DM. Open-angle glaucoma was defined as the presence of an open angle and a glaucomatous VF abnormality and/or evidence of glaucomatous optic disc damage in at least one eye. Logistic regression analysis was used to identify the risk of having OAG in persons with T2DM.

MAIN OUTCOME MEASURE

Prevalence of OAG.

RESULTS

Of the 5894 participants with complete data, 1157 (19.6%) had T2DM and 288 (4.9%) had OAG. The prevalence of OAG was 40% higher in participants with T2DM than in those without T2DM (age/gender/intraocular pressure-adjusted odds ratio, 1.4; 95% confidence interval, 1.03-1.8; P = 0.03). Trend analysis revealed that a longer duration of T2DM (stratified into 5-year increments) was associated with a higher prevalence of OAG (P<0.0001).

CONCLUSION

The presence of T2DM and a longer duration of T2DM were independently associated with a higher risk of having OAG in the LALES cohort. The high prevalences of T2DM and OAG and their association in this fastest growing segment of the United States population have significant implications for designing screening programs targeting Latinos.

Prevalence and causes of visual impairment in The Barbados Eye Study

OBJECTIVE

To determine the prevalence and causes of low vision and blindness in a predominantly black population.

DESIGN

Population-based prevalence study of a simple random sample of Barbados-born citizens aged 40 to 84 years.

PARTICIPANTS

Four thousand seven hundred nine persons (84% participation).

METHODS

The standardized protocol included best-corrected visual acuity (with a Ferris-Bailey chart), automated perimetry, lens gradings (LOCS II), and an interview. Participants with visual acuity of worse than 20/30, other positive findings, and a 10% sample also had an ophthalmologic examination that evaluated the cause and extent of vision loss (resulting from that cause), if any.

MAIN OUTCOME MEASURES

Low vision and blindness were defined as visual acuity in the better eye between 6/18 and 6/120 and visual acuity worse than 6/120, respectively (World Health Organization [WHO] criteria).

RESULTS

Of the 4631 participants with complete examinations, 4314 (93%) reported their race as black, 184 (4%) reported their race as mixed (black and white), and 133 (3%) reported their race as white or other. Low vision was found in 5.9% of the black, 2.7% of the mixed, and 3.0% of white or other participants. Bilateral blindness was similar for black and mixed race participants (1.7% and 1.6%, respectively) and was not found in whites. Among black and mixed participants, the prevalence of low vision increased with age (from 0.3% at 40-49 years to 26.8% at 80 years or older). The prevalence of blindness was higher (P < 0.001) for men than women at each age group (0.5% versus 0.3% at ages 40-49 and 10.9% versus 7.3% at 80 years or more). Sixty percent of blindness was due to open-angle glaucoma and age-related cataract, each accounting for more than one fourth of cases. Other major causes were optic atrophy or neuropathy and macular and other retinal diseases. Few cases of blindness were due to diabetic retinopathy (1.4%), and none were due to age-related macular degeneration.

CONCLUSIONS

Using the WHO criteria, prevalence of visual impairment was high in this African-origin population, particularly at older ages. Most blindness was due to open-angle glaucoma and cataract, with open-angle glaucoma causing a higher proportion of blindness than previously reported. The increased prevalence of blindness in men may be due to the increased male prevalence of glaucoma in this population and warrants further investigation. Results underline the need for blindness prevention programs, with emphasis on effective treatment of age-related cataract and enhancing strategies for early detection and treatment of open-angle glaucoma.

African Descent and Glaucoma Evaluation Study (ADAGES): II. Ancestry differences in optic disc, retinal nerve fiber layer, and macular structure in healthy subjects

OBJECTIVE

To define differences in optic disc, retinal nerve fiber layer, and macular structure between healthy participants of African (AD) and European descent (ED) using quantitative imaging techniques in the African Descent and Glaucoma Evaluation Study (ADAGES).

METHODS

Reliable images were obtained using stereoscopic photography, confocal scanning laser ophthalmoscopy (Heidelberg retina tomography [HRT]), and optical coherence tomography (OCT) for 648 healthy subjects in ADAGES. Findings were compared and adjusted for age, optic disc area, and reference plane height where appropriate.

RESULTS

The AD participants had significantly greater optic disc area on HRT (2.06 mm(2); P < .001) and OCT (2.47 mm(2); P < .001) and a deeper HRT cup depth than the ED group (P < .001). Retinal nerve fiber layer thickness was greater in the AD group except within the temporal region, where it was significantly thinner. Central macular thickness and volume were less in the AD group.

CONCLUSIONS

Most of the variations in optic nerve morphologic characteristics between the AD and ED groups are due to differences in disc area. However, differences remain in HRT cup depth, OCT macular thickness and volume, and OCT retinal nerve fiber layer thickness independent of these variables. These differences should be considered in the determination of disease status.

The Advanced Glaucoma Intervention Study (AGIS): 13. Comparison of treatment outcomes within race: 10-year results

OBJECTIVE

To present for black and white patients with medically uncontrolled glaucoma 10-year results of treatment with 1 of 2 randomly assigned surgical intervention sequences.

DESIGN

Randomized clinical trial.

PARTICIPANTS

Three hundred thirty-two black patients (451 eyes) and 249 white patients (325 eyes). Eyes had glaucoma that could not be controlled with medications alone.

METHODS

Eyes were randomly assigned to 1 of 2 sequences: argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) or trabeculectomy-ALT-trabeculectomy (TAT). Second and third interventions were offered after failure of the preceding intervention. Minimum required intraocular pressure (IOP) for intervention failure ranged upward from 18 mmHg, the value depending on whether recent optic disc or visual field (VF) deterioration occurred, and on the magnitude of the field defect. Patients were observed every 6 months, with total potential follow-up ranging from 8 years, 4 months to 13 years.

MAIN OUTCOME MEASURES

The averages over follow-up of (1) the percentage of eyes having moderate loss of VF and (2) the percentage of eyes having moderate loss of visual acuity (VA).

RESULTS

Race-treatment interactions in VF and VA loss are significant for the 2 main outcome measures; therefore, results of treatment sequence differences are presented by race. In black patients the average percent of eyes with VF loss was less in the ATT sequence than in the TAT sequence, a difference that is not statistically significant at any visit. In white patients, conversely, after 18 months the average percent of eyes with VF loss was less in the TAT sequence, a difference that increases and is statistically significant in years 8 to 10. In both black and white patients, the average percent of eyes with VA loss was less in the ATT sequence; this difference is statistically significant throughout 10 follow-up years in black patients and is statistically significant only for the first year in white patients. In both black and white patients, average IOP reductions were greater in the TAT sequence, though the TAT-ATT difference was substantially greater in white patients. In both black and white patients, first-intervention failure rates were substantially lower for trabeculectomy than for trabeculoplasty. Ten-year cumulative incidence of unilateral VF impairment comparable to legal blindness was modest in eyes of black (ATT 11.9%, TAT 18.5%) and white (ATT 9.9%, TAT 7.3%) patients.

CONCLUSIONS

Although IOP was lowered in both sequences in black and white patients with medically uncontrolled glaucoma, long-term visual function outcomes were better for the ATT sequence in black patients and better for the TAT sequence in white patients.

Temba glaucoma study: a population-based cross-sectional survey in urban South Africa

OBJECTIVE

To determine the prevalence and features of glaucoma in an urban South African black population.

DESIGN

Random sampling cross-sectional population survey.

PARTICIPANTS

Black residents of Temba, North West Province, South Africa, age > or =40 years.

MAIN OUTCOME MEASURES

Automated visual field testing and detailed, standardized slit-lamp examination were attempted on all subjects. Glaucoma was diagnosed by use of the scheme proposed by the Working Group for Defining Glaucoma of the International Society of Geographical and Epidemiologic Ophthalmology on the basis of evidence of end-organ damage.

RESULTS

Of 1120 subjects, 839 (74.9%) were examined. The age- and gender-adjusted prevalence of glaucoma of all types was 5.3% (95% confidence interval [CI], 3.9%-7.1%). Primary open-angle glaucoma (POAG) was the most common glaucoma diagnosis, with an adjusted prevalence of 2.9% (95% CI, 1.9%-4.3%). Secondary glaucoma occurred with an adjusted prevalence of 2.0% (95% CI, 1.2%-3.3%). Exfoliative glaucoma was responsible for 16% of all glaucoma cases. The prevalence of primary angle-closure glaucoma was 0.5% (95% CI, 0.13%-1.2%). Of all subjects with glaucoma, 58% were blind in at least one eye. The prevalence of all types of glaucoma increased with age. Of subjects with POAG, 87% had not been previously diagnosed.

CONCLUSIONS

The prevalence of glaucoma in this South African population was higher than that found in white populations, and most cases were undiagnosed and untreated. Glaucoma is a major cause of blindness in this population.

The ISNT Rule and Differentiation of Normal From Glaucomatous Eyes

OBJECTIVE

To determine whether the ISNT rule (that normal eyes show a characteristic configuration for disc rim thickness of inferior > or = superior > or = nasal > or = temporal), widely used for clinical evaluation of the optic nerve head, can differentiate normal from glaucomatous eyes.

METHODS

All subjects underwent complete eye examination, including achromatic automated perimetry, simultaneous stereoscopic disc photography, and confocal scanning laser ophthalmoscopy. Subjects with normal eyes had no evidence of glaucoma or ocular hypertension and had normal perimetry measurements. Subjects with glaucoma had a reproducible visual field defect. One eye from each subject was randomly enrolled. The ISNT rule was assessed by masked evaluation of disc photographs at the 3, 6, 9, and 12 o'clock positions.

RESULTS

Sixty-six subjects with normal eyes (33 black and 33 white individuals) and 43 with open-angle glaucoma (15 black and 28 white individuals) were enrolled. The ISNT rule was intact in 52 (79%) of 66 normal eyes and 12 (28%) of 43 glaucomatous eyes (P<.001). Multiple logistic regression indicated that the odds ratio for glaucoma associated with violation of the ISNT rule was 6.04 (95% confidence interval, 1.74-20.95) after adjustment for age; race was not a confounder of this association.

CONCLUSION

The ISNT rule is useful in differentiating normal from glaucomatous optic nerves and is unaffected by race.

Distribution of intraocular pressure. The Barbados Eye Study

OBJECTIVE

To provide data on the distribution of intraocular pressure (IOP) in a predominantly black population, which has a high prevalence of open-angle glaucoma.

DESIGN

Population-based prevalence study.

SETTING AND PARTICIPANTS

Participants (N = 4601) (age range, 40-84 years) who had undergone applanation tonometry measurements in the Barbados Eye Study. Self-reported race was 93% black, 4% mixed (black and white), and 3% white or other.

DATA COLLECTION

A standardized protocol included applanation tonometry and other ocular measurements, fundus photography, demographic data, and an interview.

MAIN OUTCOME MEASURES

The average of 3 IOP measurements at the Barbados Eye Study visit was used to compare IOP by self-reported race. Descriptive data on IOP by age, sex, glaucoma status, and cup-disc ratio were examined in the black population.

RESULTS

The IOP was highest in the population of African origin. The mean (+/-SD) IOP values for black, mixed, and white participants were 18.7 +/- 5.2, 18.2 +/- 3.8, and 16.5 +/- 3.0 mm Hg, respectively. An IOP greater than 21 mm Hg was present in 18.4%, 13.6%, and 4.6% of the black, mixed, and white participants, respectively. In analyses that were adjusted for age, sex, and glaucoma status, such values were 5 times as likely in black than white participants and 3.5 times as likely in mixed race participants (P < .01). Among the black participants, the mean IOP increased approximately 1 mm Hg for every increase in 10 years of age. After excluding persons with any type of glaucoma, suspected glaucoma, or a history of glaucoma treatment, women had significantly (P < .01) higher IOP values; however, no significant IOP trends by sex were evident in the group with glaucoma. The IOP was also positively associated (P < .05) with vertical cup-disc ratios. After 2 visits, the IOP remained 21 mm Hg or less in 21% of the persons with glaucoma vs 64% of those without glaucoma.

CONCLUSIONS

In the black participants, the IOP was higher than in the white participants. The IOP was also associated with age and cup-disc ratios. The results showed that open-angle glaucoma and a high IOP alone have a different distribution by sex; although open-angle glaucoma was more frequent in men, ocular hypertension was more frequent in women. These data have implications for the detection and causation of open-angle glaucoma in this high-risk population.