Potentially Missed Opportunities in Prevention of Acute Angle-Closure Crisis.

Importance: If an anatomic narrow angle is not appropriately diagnosed and treated, it can result in acute angle-closure crisis (AACC) and lead to substantial vision loss. Objective: To identify patients who presented with AACC and assess for factors that may have been associated with risk of developing it. Design, Setting, and Participants: This population-based retrospective cohort study conducted from January 1, 2001, to December 31, 2015, included a 20% nationwide sample of 1179 Medicare beneficiaries. Patients aged 40 years or older with AACC were identified with billing codes. A 2-year lookback period from the date of initial presentation of AACC was used to identify patients who had at least 1 eye care visit, received a diagnosis of open-angle glaucoma (OAG) or suspected OAG, or received at least 1 medication associated with risk of AACC. Of the patients who had at least 1 eye care visit, those who underwent gonioscopy, received a diagnosis of an anatomic narrow angle before developing AACC, or both were identified. Main Outcomes and Measures: Proportions of patients who had at least 1 eye care visit, had OAG or suspected OAG, received at least 1 medication associated with risk of AACC, underwent gonioscopy, or received a diagnosis of an anatomic narrow angle before development of AACC. Results: A total of 1179 patients had a confirmed diagnosis of AACC. The mean (SD) age of patients with AACC was 66.7 (11.8) years (range, 40-96 years), 766 were women (65.0%), 57 were Asian (4.8%), 109 were Black (9.2%), 126 were Latino (10.7%), 791 were White (67.1%), and 96 were other race and ethnicity (8.1%). Of these patients, only 796 (67.5%) consulted an optometrist or ophthalmologist at least once during the 2-year lookback period. A total of 464 individuals (39.4%) had OAG or suspected OAG, and 414 (35.1%) had received at least 1 medication associated with increased risk of AACC before developing it. Of the 796 patients who consulted an optometrist or ophthalmologist in the lookback period, less than one-third underwent gonioscopy in the 2 years before developing AACC (n = 264 [33.2%]), and less than one-half of all patients undergoing gonioscopy received a diagnosis of an anatomic narrow angle (n = 113 [42.8%]). Most patients underwent gonioscopy in the 1 to 4 weeks preceding the AACC. Conclusions and Relevance: In this group of Medicare patients, there appear to have been multiple opportunities for interventions that may have averted AACC. Interventions aimed at addressing risk factors associated with AACC and improving performance of gonioscopy might be associated with reduced risk for ocular morbidity.

Assessment of the Impact of an Endpoint Committee in the Ocular Hypertension Treatment Study.

PURPOSE: To assess the impact of a masked Endpoint Committee on estimates of the incidence of primary open-angle glaucoma (POAG) treatment efficacy and statistical power of the Ocular Hypertension Treatment Study-Phase 1, 1994-2002 (OHTS-1). DESIGN: Retrospective interrater reliability analysis of endpoint attribution by the Endpoint Committee. METHODS: After study closeout, we recalculated estimates of endpoint incidence, treatment efficacy, and statistical power using all-cause endpoints and POAG endpoints. To avoid bias, only the first endpoint per participant is included in this report. RESULTS: The Endpoint Committee reviewed 267 first endpoints from 1636 participants. The Endpoint Committee attributed 58% (155 of 267) of the endpoints to POAG. The incidence of all-cause endpoints vs POAG endpoints was 19.5% and 13.2%, respectively, in the observation group and 13.1% and 5.8%, respectively, in the medication group. Treatment effect for all-cause endpoints was a 33% reduction in risk (relative risk = 0.67, 95% confidence interval [CI] of 0.54-0.84) and a 56% reduction in risk for POAG endpoints (relative risk = 0.44, 95% CI of 0.31-0.61). Post hoc statistical power for detecting treatment effect was 0.94 for all-cause endpoints and 0.99 for POAG endpoints. CONCLUSION: Endpoint Committee adjudication of endpoints improved POAG incidence estimates, increased statistical power, and increased calculated treatment effect by 23%. An Endpoint Committee should be considered in therapeutic trials when common ocular and systemic comorbidities, other than the target condition, could compromise study results.

The potential association between postmenopausal hormone use and primary open-angle glaucoma.

IMPORTANCE: Retinal ganglion cells are known to express estrogen receptors and prior studies have suggested an association between postmenopausal hormone (PMH) use and decreased intraocular pressure, suggesting that PMH use may decrease the risk for primary open-angle glaucoma (POAG). OBJECTIVE: To determine whether the use of 3 different classes of PMH affects the risk for POAG. DESIGN, SETTING, AND PARTICIPANTS: Retrospective longitudinal cohort analysis of claims data from women 50 years or older enrolled in a US managed-care plan for at least 4 years in which enrollees had at least 2 visits to an eye care provider during the period 2001 through 2009. EXPOSURE: Postmenopausal hormone medications containing estrogen only, estrogen + progesterone, and estrogen + androgen, as captured from outpatient pharmacy claims over a 4-year period. MAIN OUTCOMES AND MEASURES: Hazard ratios (HRs) for developing incident POAG. RESULTS: Of 152,163 eligible enrollees, 2925 (1.9%) developed POAG. After adjustment for confounding factors, each additional month of use of PMH containing estrogen only was associated with a 0.4% reduced risk for POAG (HR, 0.996 [95% CI, 0.993-0.999]; P = .02). The risk for POAG did not differ with each additional month of use of estrogen + progesterone (HR, 0.994 [95% CI, 0.987-1.001]; P = .08) or estrogen + androgen (HR, 0.999 [95% CI, 0.988-1.011]; P = .89). CONCLUSIONS AND RELEVANCE: Use of PMH preparations containing estrogen may help reduce the risk for POAG. If prospective studies confirm the findings of this analysis, novel treatments for this sight-threatening condition may follow.

Surveillance for ocular hypertension: an evidence synthesis and economic evaluation.

OBJECTIVES: To determine effective and efficient monitoring criteria for ocular hypertension [raised intraocular pressure (IOP)] through (i) identification and validation of glaucoma risk prediction models; and (ii) development of models to determine optimal surveillance pathways. DESIGN: A discrete event simulation economic modelling evaluation. Data from systematic reviews of risk prediction models and agreement between tonometers, secondary analyses of existing datasets (to validate identified risk models and determine optimal monitoring criteria) and public preferences were used to structure and populate the economic model. SETTING: Primary and secondary care. PARTICIPANTS: Adults with ocular hypertension (IOP > 21 mmHg) and the public (surveillance preferences). INTERVENTIONS: We compared five pathways: two based on National Institute for Health and Clinical Excellence (NICE) guidelines with monitoring interval and treatment depending on initial risk stratification, 'NICE intensive' (4-monthly to annual monitoring) and 'NICE conservative' (6-monthly to biennial monitoring); two pathways, differing in location (hospital and community), with monitoring biennially and treatment initiated for a ≥ 6% 5-year glaucoma risk; and a 'treat all' pathway involving treatment with a prostaglandin analogue if IOP > 21 mmHg and IOP measured annually in the community. MAIN OUTCOME MEASURES: Glaucoma cases detected; tonometer agreement; public preferences; costs; willingness to pay and quality-adjusted life-years (QALYs). RESULTS: The best available glaucoma risk prediction model estimated the 5-year risk based on age and ocular predictors (IOP, central corneal thickness, optic nerve damage and index of visual field status). Taking the average of two IOP readings, by tonometry, true change was detected at two years. Sizeable measurement variability was noted between tonometers. There was a general public preference for monitoring; good communication and understanding of the process predicted service value. 'Treat all' was the least costly and 'NICE intensive' the most costly pathway. Biennial monitoring reduced the number of cases of glaucoma conversion compared with a 'treat all' pathway and provided more QALYs, but the incremental cost-effectiveness ratio (ICER) was considerably more than £30,000. The 'NICE intensive' pathway also avoided glaucoma conversion, but NICE-based pathways were either dominated (more costly and less effective) by biennial hospital monitoring or had a ICERs > £30,000. Results were not sensitive to the risk threshold for initiating surveillance but were sensitive to the risk threshold for initiating treatment, NHS costs and treatment adherence. LIMITATIONS: Optimal monitoring intervals were based on IOP data. There were insufficient data to determine the optimal frequency of measurement of the visual field or optic nerve head for identification of glaucoma. The economic modelling took a 20-year time horizon which may be insufficient to capture long-term benefits. Sensitivity analyses may not fully capture the uncertainty surrounding parameter estimates. CONCLUSIONS: For confirmed ocular hypertension, findings suggest that there is no clear benefit from intensive monitoring. Consideration of the patient experience is important. A cohort study is recommended to provide data to refine the glaucoma risk prediction model, determine the optimum type and frequency of serial glaucoma tests and estimate costs and patient preferences for monitoring and treatment. FUNDING: The National Institute for Health Research Health Technology Assessment Programme.

The relationship between statin use and open-angle glaucoma.

PURPOSE: To determine whether 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) affect the risk of developing open-angle glaucoma (OAG) in persons with hyperlipidemia. DESIGN: Retrospective, longitudinal cohort analysis. PARTICIPANTS: Individuals aged ≥60 years with hyperlipidemia enrolled in a national United States managed care network between 2001 and 2009. METHODS: Multivariable Cox regression analyses were performed to assess the relationship between statin use and the development of OAG (from no prior OAG diagnosis), progression from a prior diagnosis of glaucoma suspect to a diagnosis of OAG, and need for medical or operative interventions for OAG. Regression models were adjusted for sociodemographic factors and medical and ocular comorbidities. MAIN OUTCOME MEASURES: Hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS: Of the 524 109 individuals with hyperlipidemia, 316 182 (60%) had ≥1 outpatient prescription for statins. The hazard of developing OAG decreased 0.3% (adjusted HR, 0.997; 95% CI 0.994-0.999) for every additional month of statin consumption. Individuals with hyperlipidemia who took statins continuously for 2 years had an 8% (adjusted HR, 0.922; 95% CI, 0.870-0.976) decreased OAG risk relative to those who received no statin therapy. The hazard of progressing from a diagnosis of glaucoma suspect to OAG decreased 0.4% (adjusted HR, 0.996; 95% CI, 0.993-0.999) for every additional month of statin exposure. Individuals who took statins continuously for 2 years had a 9% (adjusted HR, 0.907; 95% CI, 0.846-0.973) decreased risk of progressing from glaucoma suspect to OAG relative to those who received no statin therapy. The hazard of requiring medical treatment for OAG decreased 0.4% (adjusted HR, 0.996; 95% CI, 0.993-0.998) for every additional month of statin exposure. No differences in need for glaucoma surgery were noted among those with OAG who were and were not taking statins (adjusted HR, 1.002; 95% CI, 0.994-1.010). CONCLUSIONS: Statin use was associated with a significant reduction in the risk of OAG among persons with hyperlipidemia. Given the mounting evidence of statin protection against OAG including both basic science and observational clinical studies, an interventional prospective study might provide additional insights into the role of statins in the prevention of early OAG.

Glaucoma in the English-speaking Caribbean.

The Barbados Eye Studies have provided the most comprehensive information on the major eye diseases in African origin populations to date. Black Barbadians have among the highest rates of primary open-angle glaucoma (OAG) reported to date in a population-based study (7.0%). Incidence rates of OAG over a nine-year follow-up period were 0.5% per year, and two to five times higher than reported in predominantly Caucasian populations. Risk factors for OAG included older age, male gender higher intraocular pressure, positive glaucoma family history, in addition to lean body mass and a positive cataract history. Low blood pressure to intraocular pressure relationships were also found to increase OAG risk, suggesting an aetiologic role for low vascular perfusion of the optic nerve. Recent analyses revealed a region on chromosome 2 associated with increased OAG risk, which has potential implications for early diagnosis and treatment. Approximately 50% of Barbadians with OAG were unaware of having the disease in the baseline study and this situation remained unchanged nine years later open-angle glaucoma causes painless, irreversible loss of vision and there are clear reasons why screening may be of particular public health importance in high risk African descent populations, given the benefits of early detection and appropriate treatment. There are data that suggest that it would be cost-effective to conduct open-angle glaucoma screening in Barbados and this has implications for policy and care, with the ultimate aim of reducing glaucoma-related blindness.

Physical activity and ocular perfusion pressure: the EPIC-Norfolk eye study.

PURPOSE: To examine the relationship between physical activity and ocular perfusion pressure (OPP), a consistent risk factor for glaucoma. METHODS: The relationship between previous physical activity and current OPP in 5650 participants aged 48 to 90 who attended the first (1993-1997) and third (2006-2010) health check as part of the European Prospective Investigation into Cancer (EPIC)-Norfolk study was examined. Usual combined physical activity at work and leisure was assessed using a validated instrument. Individuals were categorized as inactive, moderately inactive, moderately active, or active. Three IOP measurements were obtained (Ocular Response Analyzer [ORA]; Reichert, Inc., Depew, NY). Mean Goldmann correlated IOP (IOPg) from one eye was used in the analysis. Systolic and diastolic blood pressure (BP) were recorded as the mean of two measurements taken with a sphygmomanometer. Associations between physical activity and low (≤40 mm Hg) mean OPP (2/3 mean arterial pressure - IOP) and low (≤50 mm Hg) diastolic OPP (diastolic BP - IOP) were tested using logistic regression, adjusting for age, sex, body mass index, social class, IOP, and BP. RESULTS: Active people had a lower risk of mean OPP ≤ 40 mm Hg and diastolic OPP ≤ 50 mm Hg after adjusting for age, sex, social class, and body mass index (odds ratio, 0.75; 95% confidence interval [CI], 0.60-0.93; P < 0.01) and (odds ratio, 0.73, 95% CI, 0.58-0.93; P = 0.01), respectively. The association between physical activity and perfusion pressure was independent of IOP, but largely mediated through diastolic BP. CONCLUSIONS: Lower levels of physical activity were associated with lower OPP. Further research is needed to investigate the potential benefit of increased physical activity as a safe and simple method of modifying glaucoma risk.

Glaucoma in the English-speaking Caribbean / El glaucoma en el Caribe Anglófono

The Barbados Eye Studies have provided the most comprehensive information on the major eye diseases in African origin populations to date. Black Barbadians have among the highest rates of primary open-angle glaucoma (OAG) reported to date in a population-based study (7.0%). Incidence rates of OAG over a nine-year follow-up period were 0.5% per year, and two to five times higher than reported in predominantly Caucasian populations. Risk factors for OAG included older age, male gender, higher intraocular pressure, positive glaucoma family history, in addition to lean body mass and a positive cataract history. Low blood pressure to intraocular pressure relationships were also found to increase OAG risk, suggesting an aetiologic role for low vascular perfusion of the optic nerve. Recent analyses revealed a region on chromosome 2 associated with increased OAG risk, which has potential implications for early diagnosis and treatment. Approximately 50% of Barbadians with OAG were unaware of having the disease in the baseline study and this situation remained unchanged nine years later. Open-angle glaucoma causes painless, irreversible loss of vision and there are clear reasons why screening may be of particular public health importance in high risk African descent populations, given the benefits of early detection and appropriate treatment. There are data that suggest that it would be cost-effective to conduct Open-angle glaucoma screening in Barbados and this has implications for policy and care, with the ultimate aim of reducing glaucoma-related blindness.

Los Estudios Oftalmológicos de Barbados han proporcionado la información más integral sobre las principales enfermedades oculares en las poblaciones de origen africano hasta la fecha. Los barbadenses negros se cuentan entre las poblaciones con tasas más altas de glaucoma de ángulo abierto (GAA) hasta la fecha, según un estudio de base poblacional realizado (7.0%). Las tasas de incidencia de GAA en un período de seguimiento de nueve años, fueron 0.5% por año - de dos a cinco veces mayores que las reportadas predominantemente en poblaciones caucásicas. Los factores de riesgo para el GAA incluyeron los años de edad, el ser varón, el tener presión intraocular alta, y una historia de pruebas positivas de glaucoma en la familia, además pobre masa corporal, y una historia positiva de catarata. Se halló que las relaciones de baja presión sanguínea con respecto a la presión intra-ocular, aumentan el riesgo de GAA, sugiriendo así un papel etiológico a la bajo perfusión vascular del nervio óptico. Recientes análisis revelaron una región en el cromosoma dos, asociada con el aumento de riesgo del GAA, con implicaciones potenciales para un diagnóstico y tratamiento tempranos. Aproximadamente el 50% de los barbadenses con GAA no tenían conciencia de tener la enfermedad en el estudio inicial de partida, y esta situación permanecería invariable nueve años más tarde. El glaucoma de ángulo abierto causa una pérdida sin dolor e irreversible de la visión, y hay razones claras por las que el tamizaje puede revestir particular importancia para la salud pública de poblaciones de ascendencia africana en alto riesgo, dados los beneficios de una detección precoz y un tratamiento adecuado. Hay datos que sugieren que sería costo-efectivo llevar a cabo un tamizaje del GAA en Barbados, lo cual tendría implicaciones tanto en relación con las políticas a seguir cuanto para la atención misma, cuyo objetivo final reducir la ceguera relacionada con el glaucoma.

Developing the clinical components of a complex intervention for a glaucoma screening trial: a mixed methods study.

BACKGROUND: Glaucoma is a leading cause of avoidable blindness worldwide. Open angle glaucoma is the most common type of glaucoma. No randomised controlled trials have been conducted evaluating the effectiveness of glaucoma screening for reducing sight loss. It is unclear what the most appropriate intervention to be evaluated in any glaucoma screening trial would be. The purpose of this study was to develop the clinical components of an intervention for evaluation in a glaucoma (open angle) screening trial that would be feasible and acceptable in a UK eye-care service. METHODS: A mixed-methods study, based on the Medical Research Council (MRC) framework for complex interventions, integrating qualitative (semi-structured interviews with 46 UK eye-care providers, policy makers and health service commissioners), and quantitative (economic modelling) methods. Interview data were synthesised and used to revise the screening interventions compared within an existing economic model. RESULTS: The qualitative data indicated broad based support for a glaucoma screening trial to take place in primary care, using ophthalmic trained technical assistants supported by optometry input. The precise location should be tailored to local circumstances. There was variability in opinion around the choice of screening test and target population. Integrating the interview findings with cost-effectiveness criteria reduced 189 potential components to a two test intervention including either optic nerve photography or screening mode perimetry (a measure of visual field sensitivity) with or without tonometry (a measure of intraocular pressure). It would be more cost-effective, and thus acceptable in a policy context, to target screening for open angle glaucoma to those at highest risk but for both practicality and equity arguments the optimal strategy was screening a general population cohort beginning at age forty. CONCLUSIONS: Interventions for screening for open angle glaucoma that would be feasible from a service delivery perspective were identified. Integration within an economic modelling framework explicitly highlighted the trade-off between cost-effectiveness, feasibility and equity. This study exemplifies the MRC recommendation to integrate qualitative and quantitative methods in developing complex interventions. The next step in the development pathway should encompass the views of service users.

Effect of patient's life expectancy on the cost-effectiveness of treatment for ocular hypertension.

OBJECTIVE: To assess the influence of expected life span on the cost-effectiveness of treating ocular hypertension to prevent primary open-angle glaucoma. METHODS: We used a Markov simulation model to estimate the cost and benefit of ocular hypertension treatment over a person's remaining life. We examined the influence of age on the cost-effectiveness decision in 2 ways: (1) by evaluating specific age cohorts to assess the influence of age at the initiation of treatment; and (2) by evaluating the influence of a specific life span. RESULTS: At a willingness to pay $50,000/quality-adjusted life year to $100,000/quality-adjusted life year, treatment of people with a 2% or greater annual risk of developing glaucoma was cost-effective for people aged 45 years with a life expectancy of at least 18 remaining years. However, to be cost-effective, a person aged 55 years must have a life expectancy of 21 remaining years and someone aged 65 years must have a life expectancy of 23 remaining years. CONCLUSIONS: A person with ocular hypertension must have a life expectancy of at least 18 remaining years to justify treatment at a threshold of a 2% or greater annual risk of developing glaucoma. Persons at higher levels of risk require a life expectancy of 7 to 10 additional years to justify treatment.

An introduction to decision analysis in the economic evaluation of the prevention and treatment of vision-related diseases.

Economic evaluation in the form of reports of cost-effectiveness of the treatment and prevention of disease has only recently found widespread application in the visual sciences. While economic evaluation takes a number of forms: cost-minimization analysis, cost-benefit analysis, and cost-effectiveness analysis--it is the latter that is seen most often in the evaluation of vision-related health programs. Cost-effectiveness analysis is in particular seen most commonly in its very particular form of cost-utility analysis. Decision analysis is the analytic method most commonly used to perform cost-effectiveness analysis. In decision analysis, the expected cost and effectiveness of a health program are estimated in a rigorous fashion. In this report, we take the reader through the process of decision analysis including building the tree; populating the model with parameters for risk, cost and benefit; estimating expected cost and benefit; and deterministic and probabilistic sensitivity analysis. Examples employed include prominent studies of the cost-effectiveness of photodynamic therapy for treatment of neovascular macular degeneration and the treatment ocular hypertension to prevent glaucoma.

Cost-effectiveness of treating ocular hypertension.

PURPOSE: To assess the cost-effectiveness of treating ocular hypertension (OHT) in the United States. DESIGN: A Markov model was constructed to perform a cost-effectiveness analysis. PARTICIPANTS: Patients with OHT. METHODS: The health states considered were stable OHT and glaucoma. Practice patterns for the model were derived from the Ocular Hypertension Treatment Study (OHTS), and transition probabilities were derived from previous literature. Specific unit costs used for medications, patient visits, and diagnostic and therapeutic procedures were obtained from Blue Cross/Blue Shield. The time horizon was 5 years. Costs were discounted at 3% per annum. MAIN OUTCOME MEASURE: Long-term cost effectiveness of treating OHT to prevent the development of glaucoma. RESULTS: The incremental cost-effectiveness ratio (ICER) for all OHT patients to prevent 1 case from progressing to primary open-angle glaucoma was $89,072. However, the minimally cost-effective ICER level after adjustment for risk factors identified by multivariate analysis in the OHTS were: 20 years above the average of 56 years, ICER of $45,155; 4 mmHg above the average pressure of 25 mmHg, ICER of $46,748; 40 microm less than the average central corneal thickness of 573 mum, ICER of $36,683; and a vertical cup-to-disc ratio of 0.2 wider than the average of 0.4, ICER of $35,633. CONCLUSIONS: Based on the results and practice patterns of the OHTS, treating all OHT patients seems not to be cost-effective. However, treating selective OHT patients with risk factors identified in the OHTS, for example, advancing age, higher pressures, thinner central corneal thickness, and wider vertical cup-to-disc ratios, does seem to be cost-effective for preventing the onset of glaucomatous damage.

The clinical effectiveness and cost-effectiveness of screening for open angle glaucoma: a systematic review and economic evaluation.

OBJECTIVES: To assess whether open angle glaucoma (OAG) screening meets the UK National Screening Committee criteria, to compare screening strategies with case finding, to estimate test parameters, to model estimates of cost and cost-effectiveness, and to identify areas for future research. DATA SOURCES: Major electronic databases were searched up to December 2005. REVIEW METHODS: Screening strategies were developed by wide consultation. Markov submodels were developed to represent screening strategies. Parameter estimates were determined by systematic reviews of epidemiology, economic evaluations of screening, and effectiveness (test accuracy, screening and treatment). Tailored highly sensitive electronic searches were undertaken. RESULTS: Most potential screening tests reviewed had an estimated specificity of 85% or higher. No test was clearly most accurate, with only a few, heterogeneous studies for each test. No randomised controlled trials (RCTs) of screening were identified. Based on two treatment RCTs, early treatment reduces the risk of progression. Extrapolating from this, and assuming accelerated progression with advancing disease severity, without treatment the mean time to blindness in at least one eye was approximately 23 years, compared to 35 years with treatment. Prevalence would have to be about 3-4% in 40 year olds with a screening interval of 10 years to approach cost-effectiveness. It is predicted that screening might be cost-effective in a 50-year-old cohort at a prevalence of 4% with a 10-year screening interval. General population screening at any age, thus, appears not to be cost-effective. Selective screening of groups with higher prevalence (family history, black ethnicity) might be worthwhile, although this would only cover 6% of the population. Extension to include other at-risk cohorts (e.g. myopia and diabetes) would include 37% of the general population, but the prevalence is then too low for screening to be considered cost-effective. Screening using a test with initial automated classification followed by assessment by a specialised optometrist, for test positives, was more cost-effective than initial specialised optometric assessment. The cost-effectiveness of the screening programme was highly sensitive to the perspective on costs (NHS or societal). In the base-case model, the NHS costs of visual impairment were estimated as 669 pounds. If annual societal costs were 8800 pounds, then screening might be considered cost-effective for a 40-year-old cohort with 1% OAG prevalence assuming a willingness to pay of 30,000 pounds per quality-adjusted life-year. Of lesser importance were changes to estimates of attendance for sight tests, incidence of OAG, rate of progression and utility values for each stage of OAG severity. Cost-effectiveness was not particularly sensitive to the accuracy of screening tests within the ranges observed. However, a highly specific test is required to reduce large numbers of false-positive referrals. The findings that population screening is unlikely to be cost-effective are based on an economic model whose parameter estimates have considerable uncertainty. In particular, if rate of progression and/or costs of visual impairment are higher than estimated then screening could be cost-effective. CONCLUSIONS: While population screening is not cost-effective, the targeted screening of high-risk groups may be. Procedures for identifying those at risk, for quality assuring the programme, as well as adequate service provision for those screened positive would all be needed. Glaucoma detection can be improved by increasing attendance for eye examination, and improving the performance of current testing by either refining practice or adding in a technology-based first assessment, the latter being the more cost-effective option. This has implications for any future organisational changes in community eye-care services. Further research should aim to develop and provide quality data to populate the economic model, by conducting a feasibility study of interventions to improve detection, by obtaining further data on costs of blindness, risk of progression and health outcomes, and by conducting an RCT of interventions to improve the uptake of glaucoma testing.