Glaucoma screening

Association of an Objective Structural and Functional Reference Standard for Glaucoma with Quality of Life Outcomes

PURPOSE

To compare self-reported quality-of-life (QoL) outcomes of patients diagnosed as normal, glaucoma suspect, and glaucoma based on an objective reference standard for glaucomatous optic neuropathy (GON).

DESIGN

Cross-sectional study.

PARTICIPANTS

1884 eyes of 1019 patients were included in the study.

METHODS

The data was sourced from the Duke Glaucoma Registry. Eyes were classified according to the presence and topographic correspondence of functional and structural damage, as assessed by parameters from standard automated perimetry (SAP) and spectral-domain OCT (SD-OCT). The objective diagnosis of the worse eye was used to define patient-level diagnosis. To assess QoL in the diagnostic groups, 14 unidimensional vision-related items of the National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) were used to assess QoL in the diagnostic groups. Association between NEI VFQ-25 Rasch-calibrated scores and diagnostic groups was assessed through multivariable regression that controlled for confounding demographic and socioeconomic variables such as age, sex, race, income, marriage status, insurance status, and highest education level.

MAIN OUTCOME MEASURES

NEI VFQ-25 Rasch scores compared with objective criteria diagnosis based on SAP mean deviation (MD) and SD-OCT retinal nerve fiber layer (RNFL) thickness.

RESULTS

Overall, eyes classified as normal, glaucoma suspect, and glaucoma had decreasing mean scores in SAP MD (0.2 ± 1.0 dB, -0.9 ± 2.4 dB, -6.2 ± 7.0 dB, respectively; P < 0.001) and SD-OCT RNFL thickness (97.8 ± 9.5 μm, 89.0 ± 13.1 μm, 64.5 ± 12.8 μm, respectively; P < 0.001). The mean Rasch-calibrated NEI VFQ-25 score was significantly different among normal, suspect, and glaucoma groups (82.9 ± 13.0, 78.2 ± 14.8, and 72.6 ± 16.2, respectively; P < 0.001). When adjusted for confounding socioeconomic variables, glaucoma patients had significantly worse QoL than those classified as normal (β = -6.8 Rasch score units; P < 0.001).

CONCLUSION

A glaucoma diagnosis, based on an objective reference standard for GON, was significantly associated with worse Rasch-adjusted scores of QoL. Utilization of such objective criteria may provide clinically relevant metrics with potential to improve comparability of research findings and validation of newly proposed diagnostic tools.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Evaluation of the effectiveness of ophthalmic assistants as screeners for glaucoma in North India

AIM

To assess whether ophthalmic assistants are effective in screening people for glaucoma in India.

METHODOLOGY

The study subjects were examined by both trained ophthalmic assistants and an ophthalmologist in both hospital and community settings. Specific tests for the diagnosis of glaucoma suspects included visual field examination using frequency doubling technology perimetry, intraocular pressure measurement (Tonopen), A-scan central anterior chamber depth measurement and dilated optic disc examination. The findings recorded by the ophthalmic assistants were masked to the ophthalmologist to avoid measurement bias.

RESULTS

In the hospital setting, there was a substantial level of agreement between the ophthalmic assistants and the ophthalmologist in the diagnosis of glaucoma suspects (89.29%, k=0.7, 95% confidence interval (CI)=0.54-0.86). The diagnostic accuracy of the ophthalmic assistants in detecting glaucoma suspects was high for sensitivity (95.2%, 95% CI=91.4-97.7%) but lower for specificity at 71.4% (95% CI=60.0-78.7%).In the community setting, there was a moderate level of agreement between the ophthalmic assistants and the ophthalmologist in the diagnosis of glaucoma suspects (78.23%, k=0.50, 95% CI=0.37-0.64). The diagnostic accuracy of the ophthalmic assistants in detecting glaucoma suspects was moderate for sensitivity (82.9, 95% CI=69.7-91.5%) but lower for specificity at 76.8% (95% CI=72.7-79.5%).

CONCLUSION

Ophthalmic assistants can be used for opportunistic case detection of glaucoma suspects in the community. Structured training of the ophthalmic assistants together with enhanced clinical experience would improve their performance in detecting glaucoma suspects in the community.

Cost effectiveness and cost utility of an organized screening programme for glaucoma

PURPOSE

To assess the cost effectiveness and cost utility of an organized screening programme for glaucoma. The previous cost-effectiveness studies of screening show inconsistent results, and the cost utility of screening has not been assessed.

METHODS

An organized screening programme was simulated using Markov modelling in a population aged 50-79 years at 5 year intervals. The programme ended when the subjects reached the age of 80 years. The comparator was opportunistic case finding. The main outcome measures were cases and years of severe visual disability avoided, quality-adjusted life years (QALYs) gained and direct healthcare and non-healthcare costs.

RESULTS

The incremental cost of 1 year of avoided visual disability by screening was euro32 602. The cost of one QALY gained by screening was euro9023 with a discount rate of 5%. During the average 20 year time horizon considered, the cumulative incremental costs of screening in a population of 1 million people would be euro30 million, producing 3360 incremental QALYs and 930 years of avoided visual disability for 701 persons. The results were sensitive to the estimates of several parameters, especially screening cost and specificity of screening tests (96-99% specificity required).

CONCLUSION

An organized screening programme could be a cost-effective strategy especially in older age groups, in which screening is clearly more likely to be acceptable to decision makers at any level in terms of their willingness to pay for a QALY. Modelling includes some uncertainty especially concerning the specificity of diagnostic tests and screening cost.

Screening for prevention of optic nerve damage due to chronic open angle glaucoma

BACKGROUND

Open angle glaucoma (OAG) is a primary, progressive optic neuropathy; the onset is without symptoms and progression occurs silently until the advanced stages of the disease, when it affects central vision. The blindness caused by OAG is irreversible. It has often been assumed to be a condition that fulfils the criteria for population screening, although this has not been supported by other in-depth non-systematic reviews. The focus of this review was to examine the evidence for the effectiveness of screening for OAG.

OBJECTIVES

To determine the impact of screening for OAG compared with opportunistic case findings or current referral practices on the prevalence of and the degree of optic nerve damage due to OAG in screened and unscreened populations.

SEARCH STRATEGY

We included any randomised controlled trial (RCT) evaluating population-based screening programmes for OAG with a minimum one year follow up. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (which contains the Cochrane Eyes and Vision Trials Register) (Issue 1, 2006), MEDLINE (1950 to February 2006) and EMBASE (1988 to February 2006). We also searched the National Research Register (Issue 1, 2006) and Zetoc for grey literature (29 June 2006). There were no language or date restrictions in the electronic searches.

SELECTION CRITERIA

We planned to include RCTs, including cluster RCTs.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the study abstracts identified by the electronic searches. We did not find any trials that met the inclusion criteria.

MAIN RESULTS

As no trials were identified, no formal analysis was performed.

AUTHORS' CONCLUSIONS

On the basis of current evidence, population-based screening for chronic OAG cannot be recommended, although much can be done to improve awareness and encourage at risk individuals to seek testing. In wealthy countries with equitable access to high quality eye care and health education, blindness from chronic OAG should become increasingly rare; much greater challenges face poor and emerging economies and countries where there are substantial health and wealth inequalities. Effectiveness of screening for OAG can be established only by high quality RCTs.

Agreement between optometrists and ophthalmologists on clinical management decisions for patients with glaucoma

BACKGROUND/AIMS

Although optometrists have become an accepted part of the team in many hospital glaucoma clinics, their decision making ability has not been assessed formally. This study aims to document the accuracy and safety of clinical work undertaken by optometrists in the hospital setting by investigating their management decisions on follow up of patients with glaucoma.

METHODS

Four optometrists and three medical clinicians examined 50 patients each. Clinical findings were recorded as usual in the hospital records but management decisions were documented separately on a specially designed data collection form. Subsequently, the patient records and clinical findings were reviewed retrospectively and independently by two consultant ophthalmologists, who were masked to the management decisions of the optometrists and medical clinicians. The consultants' management decisions were then compared with those made by the optometrists and medical clinicians. Percentage agreements were computed together with kappa (kappa), or weighted kappa, statistics where appropriate.

RESULTS

Agreement between consultants and optometrists was 55% (kappa = 0.33) for evaluation of visual field status, 79% (kappa = 0.67) for medical management, 72-98% for other aspects of patient management, and 78% (weighted kappa = 0.35) for scheduling of next clinic appointment. Very similar levels of agreement were found between consultants and medical clinicians.

CONCLUSION

Agreement between optometrists and consultants, in glaucoma clinical decision making, was at least as good as that between medical clinicians and consultants. Within an appropriate environment, optometrists can safely work as part of the hospital glaucoma team in outpatient clinics.

Current estimates of blindness in India

BACKGROUND

Evidence based planning has been the hallmark of the blindness control programme in India. A nationwide survey was undertaken in 1999-2001 to document the magnitude and causes of blindness.

METHODS

One district each in 15 populous states was covered. 25 clusters were randomly selected in each district and all individuals aged 50 years and above were enumerated. Presenting and best corrected vision was recorded using retroilluminated logMAR tumbling E charts and detailed eye examination was offered.

RESULTS

The response rate was 89.3%. Presenting vision <6/60, in the better eye, was observed in 8.5% (95% CI: 8.1 to 8.9). Age, sex, residence, literacy, and working status were associated with blindness. The highest risk was among those aged 70+ and the illiterate. Cataract was responsible for 62.4% of bilateral blindness. Prevalence of cataract blindness was 5.3% (95% CI: 4.97 to 5.62). Reduction in blindness prevalence among people aged 50 years and above was observed compared to earlier studies.

CONCLUSION

Blindness control efforts seem to have played a part in arresting the increasing prevalence of blindness in India and there is hope that the goals of the "Vision 2020--right to sight" initiative can be achieved if there is strong political will and prioritised action.

Glaucoma case finding: a cluster-randomised intervention trial

PURPOSE

To assess the effect of an intervention comprising training in optic disc assessment, explicit referral criteria and ophthalmologist feedback on referred patients, on the number of optometrist referrals for suspected glaucoma seen at a referral site and the positive predictive value of those referrals.

METHODS

Optometric practices routinely referring to the Ealing Hospital Eye Clinic were randomly divided into two groups taking into consideration those practices, which shared an optometrist (a cluster) and the number of optometrist days worked per week. One group of practices acted as controls, while the other practices were invited to receive the intervention. Data on 397 new patients referred and presenting to Ealing Hospital with suspected glaucoma were collected over a 20-month period. The data on patients who had failed to attend their appointment were collected over 7 months of this period. The number of referrals seen, the positive predictive value of those referrals, and the attendance rate were calculated. Optometrist's opinions of the intervention were assessed qualitatively. Data relating to optometrist compliance with the intervention were also collected.

RESULTS

The number of glaucoma referrals presenting to Ealing Hospital from the intervention practices was almost double that from the control practices (210 vs 119). When cluster randomisation, the number of optometrist days per cluster and the number of assessed referrals in the preintervention period are taken into consideration, it is estimated that the intervention is associated with a 52% increase in the number of referrals reaching Ealing Hospital. However, the design effect resulting from the cluster randomisation was unexpectedly high (of the order of 13-14)and so the confidence intervals around the estimate of 52% are very wide (95% c.i. 35% decrease to 253% increase, P = 0.34). There was no evidence of an association between optometrist compliance with the intervention and the number of referrals seen at Ealing Hospital. The positive predictive value (PPV)of referrals was similar for the intervention(0.49 (95% c.i. 0.42, 0.55)) and control groups(0.46 (95% c.i. 0.33, 0.60)). Optometrist opinions of the intervention were largely favourable. All expressed a willingness to participate in future programmes.

CONCLUSION

A large difference in the number of referrals between the practice groups was observed. Since the PPV of referral was unchanged, the potential impact of the intervention in terms of numbers of new cases of glaucoma detected in the community is substantial. However, because of its large design effect, this trial does not provide conclusive evidence of an impact of the intervention on referral numbers. A considerably larger trial will be required to produce conclusive evidence of an effect.

Visual impairment and blindness in Europe and their prevention

The European region currently differs in many aspects, such as political, socioeconomic, and geographical. After substantial political changes at the beginning of the 1990s, the majority of central and eastern European countries started to rebuild their healthcare systems. It is apparent that eastern Europe represents a highly diverse region where the difference among countries broadens year after year. In highly industrialised countries of Europe, the leading causes of childhood serious visual loss are lesions of the central nervous system, congenital anomalies and retinal disorders. In the middle income countries of Europe, congenital cataract, glaucoma and, mainly, retinopathy of prematurity are highly expressed. The major cause of serious visual loss in adults in industrialised countries is age related macular degeneration. The other conditions comprise cataract, glaucoma, diabetic retinopathy, and uncorrected/uncorrectable refractive errors, along with low vision. In people of working age, diabetic retinopathy, retinopathy pigmentosa, and optic atrophy are the most frequently reported causes of serious visual loss. In the middle income countries of Europe, advanced cataract, glaucoma, and diabetic retinopathy are more frequently observed.

Frequency of sustained glaucomatous-type visual field loss and associated optic nerve cupping in Beaver Dam, Wisconsin

PURPOSE

To determine the prevalence of persisting glaucomatous-type visual field loss in a Midwestern American adult population, in association with four grades of disc cupping.

METHODS

On two separate occasions (1988-1990 and 1993-1995) 2955 predominantly Caucasian adults aged 43-84 provided medical history, underwent applanation tonometry, slit-lamp examination, quantitative suprathreshold perimetry and stereoscopic disc analysis as part of the National Institutes of Health-sponsored Beaver Dam Eye Study. Those demonstrating evidence of glaucomatous-type visual field loss at both visits were the subject of the present analysis. Among these individuals, associations were determined for four categories of optic disc cupping (vertical cup/disc < 0.5, > 0.5, > 0.6, > 0.8), intraocular pressure, blood pressure, cardiovascular pathology and prior glaucoma diagnosis.

RESULTS

Of the 2955 subjects assessed, 120 (4%; 57 women, 63 men) demonstrated glaucomatous-type visual field defects at each visit. Fifty-five of these 120 (2% of the tested population) also exhibited some degree of disc cupping in a related eye at both visits. Among these 2%, positive associations relating the extent of field loss, cupping and intraocular pressure were confirmed, but the majority in each cupping category had normal eye pressures. Only seven of the 120 were aware of the presence or suspicion of eye disease prior to the screening.

CONCLUSIONS

A majority of those found to have visual field loss and optic nerve cupping persisting together in the same eye after 3-5 years had normal pressures in each eye at both visits. Despite good access to medical care, very few who demonstrated persisting cupping and field loss (even among those with elevated eye pressure) were aware of their ocular condition through prior contact with an eye care professional.

[Glaucoma and ocular hypertension in primary care]

OBJECTIVES

To find the distribution of intra-ocular pressure (IOP) in our population over 40 and the prevalence of glaucoma (G) and ocular hypertension (OH).

DESIGN

Descriptive.

SETTING

Primary care.

SUBJECTS

990 people >= 40 years old.Measurements. Age, sex, body mass index (BMI), ophthalmic history, risk factors, visual sharpness (optotype), ophthalmoscopy and IOP (applanation tonometry). Patients with back-of-eye disorders and/or IOP >= 21 mmHg were referred to the ophthalmologist for assessment (campimeter).

RESULTS

870 people, average age 54.66 and 45.4% of them men. Mean IOP was 12.96 in the right eye and 13.27 in the left, with significant differences between them, but not between sexes or age-groups. 70 patients were referred (11 for IOP >= 21, 54 for disturbance perceived by ophthalmoscope and 5 for both reasons). The ophthalmologist classified 9 as G, 12 as OH and 15 as suspected G. We calculated 1.81% (95% CI, 0.98-2.63) prevalence of G in the >= 40s, including 9 cases already known. OH prevalence was 1.61% (95% CI, 0.82-2.39). Through logistical regression, we found greater risk of G in people with myopia (OR adjusted for age and sex = 3.01) and Hypertriglyceridaemia (ORa, 6.34). OH risk was significantly greater in patients with BMI >= 30 (ORa, >= 4.20).

CONCLUSIONS

Glaucoma prevalence confirms published findings from other similar populations, while IOP and OH prevalence were much less here. Given that half G cases are undiagnosed, we believe its early detection in primary care should be highlighted, at least in at-risk groups.

Screening models for glaucoma

For social and economic reasons, glaucoma screening is a useful and necessary task, with possible benefits for individuals and the health care system arising from the early diagnosis and early therapy of patients with glaucoma. Early treatment of patients with glaucoma decreases the probability that those patients will become blind and lowers the direct and indirect costs for patients with glaucoma. Most of the reported studies dealing with glaucoma screening used only one parameter (eg, intraocular pressure) to detect and to discriminate glaucoma patients from healthy subjects. Glaucoma screening devices might be combined to obtain the best specificity and sensitivity. Because the diagnosis of glaucoma is very closely associated with a morphologic change in the optic nerve head, one screening parameter should be the morphology of the papilla. To increase specificity and sensitivity, a combination of morphologic and functional testing might be useful. In this review, we report the context of glaucoma screening in terms of health economics, the testing quality of devices for functional and morphologic screening, and the results of a pilot study.

Deprivation and late presentation of glaucoma: case-control study

OBJECTIVE

To identify socioeconomic risk factors for first presentation advanced glaucomatous visual field loss.

DESIGN

Hospital based case-control study with prospective identification of patients.

SETTING

Three hospital eye departments.

PARTICIPANTS

Consecutive patients newly diagnosed with glaucoma (n=220). Cases (late presenters) were those presenting with advanced glaucoma (n=110), controls were those with early glaucoma (n=110).

RESULTS

Median underprivileged area scores were higher among late presenters (29.5; interquartile range 9.0-42.2) than in the control group (21.3; 6.1-37.4) (P=0.035). Late presenters were more likely to be of lower occupational class (odds ratio adjusted for age and referral centre 20.1 (95% confidence interval 2.6 to 155) for group III compared with group I-II and 86.0 (11.0 to 673 for group IV-V compared with group I-II), to have no access to a car (2.2; 1.2 to 4.0), to have left full time education at age 14 or less (7.5; 2.3 to 24.7), and to be tenants rather than owner occupiers (local authority tenants 3.2; 1.7 to 5.8, private tenants 2.1; 0.7 to 5.8). Effects of deprivation were partly accounted for by family history of glaucoma, time since last visit to an optometrist, and lack of an initial diagnosis of glaucoma by an optometrist.

CONCLUSIONS

Area and individual level deprivation were both associated with late presentation of glaucoma. Existing evidence shows that late presentation is an important risk factor for subsequent blindness. Deprived groups thus seem to be at greater risk of going blind from glaucoma. Material deprivation may be associated with more aggressive disease as well as later presentation.

Use of eye care services by older Australians: the Blue Mountains Eye Study

PURPOSE

To assess utilization of eye care services in an older Australian population.

METHODS

The Blue Mountains Eye Study examined 3654 permanent residents aged 49 years or older from two New South Wales postcode areas. At interview, we collected information about past attendance to eye care practitioners, demographic and socio-economic status variables and past medical and eye history. Full-time optometric and part-time ophthalmic services were available in this community.

RESULTS

Almost all participants (99%) had seen either an ophthalmologist or optometrist in the past, with 62, 27, 7 and 3% having last attended in the last 2, 2-5, 5-10 and > 10 years, respectively. Among those participants (2251) who had been seen in the last 2 years, 50.2% (1131) last saw an ophthalmologist, 48.6% (1094) last saw an optometrist and 26 (1.2%) could not state whom they saw. After adjusting for age and sex, factors statistically significantly associated with attending an ophthalmologist included older age, female gender, higher socio-economic status, moderate to high myopia and presence of systemic disease (diabetes, hypertension) or any significant eye pathology. Factors statistically significantly associated with attending an optometrist were younger age, living alone, not currently married, being able to go out alone, having better presenting visual acuity, hyperopia and absence of diabetes or significant eye pathology, including moderate to high myopia.

CONCLUSIONS

Findings from this study indicate that whether people use eye care services and whom they visit is mainly driven by need factors. Although there was considerable overlap, this study found relatively appropriate utilization of eye care services by this population.

The cost-effectiveness of various modes of screening for primary open angle glaucoma

Various modes of screening for glaucoma were defined in terms of different combinations of the three main tests (ophthalmoscopy (O), tonometry (T), and perimetry (P)), together with associated referral criteria. The number of referrals and true positives generated by each mode was estimated for a model population, which was distributed with respect to age, intraocular pressure (IOP), optic disc condition, visual field defects, family history of glaucoma, and myopic status, as indicated by epidemiological studies. The costs of primary examination, and also of the secondary examination of referrals, were estimated for each mode, thus enabling the total cost per true positive to be calculated (in Pound sterling at 1995 UK prices, subsequently converted to US dollars at Pound 1.00 = $1.55.) The modes using O and T routinely, with P either routinely or selectively on all glaucoma high-risk groups, were found to provide the best balance between sensitivity (> or = 80%) and cost per true positive. The latter was around $850 when the cost of ophthalmoscopy could be shared as part of a general eye examination. The calculations assumed a 0.6% prevalence of previously undetected glaucomas in the community: with higher prevalences, costs per true positive would be lower. Screening the 40-59 years age group was found to be about as economic as for older people, when life expectancy was taken into account. It was concluded that glaucoma screening of people over age 40 years could be justifiable, provided that it is worth more than about $850 to detect a new case. Whilst based on UK values, the analysis could be applied to different primary health care settings in other countries.

Screening for glaucoma. Why is the disease underdetected?

A review of 15 population-based glaucoma prevalence surveys in Western Europe, the US, the West Indies and Japan shows that the proportion of patients with the condition who had previously gone undetected was generally at least 50%. Possible reasons for underdetection of glaucoma have been considered in relation to England and Wales, where most patients with glaucoma are initially detected during the course of sight tests in connection with providing spectacle lenses. It was found that: (i) a high proportion of the population over 40 years of age attends fairly regularly for a sight test, (ii) the standard of primary testing for glaucoma is very uneven--those examiners who test comprehensively detect about 50% more cases than average; and (iii) referral criteria, which reflect the need not to overload hospital eye clinics, inevitably exclude many patients who are in apparently low risk categories. Both the population survey data and the subsequent analysis suggest that underdetection is most pronounced in patients with glaucoma of the normal pressure type.