Amblyopia Screening Research Articles

Objective detection of amblyopia and strabismus . . . not just screening for risk factors

To date, preschool vision screening for strabismus and/or amblyopia involves assessment of risk factors, including refractive error and stereoacuity. Most children who are positive for risk factors never develop strabismus or amblyopia. The Pediatric Vision Scanner (PVS) is the first objective, automated screening device that directly assesses bifoveal fixation. This study was undertaken to assess the ability of the PVS to identify patients with strabismus and/or amblyopia in a pediatric ophthalmology office setting.

Childhood Vision Screening in Canada: Public Health Evidence and Practice

Objectives: Best practice guidelines recommend vision testing in children 3 to 5 years of age for the prevention of amblyopia; however, universal vision screening is controversial. In Canada, amblyopia screening can be the responsibility of physicians, optometrists, and/or Public Health. We review the evidence underlying preschool vision screening for amblyopia using an Evidence-based Public Health (EBPH) approach, and consider implications for the Public Health provision of universal screening programs for amblyopia in Canadian jurisdictions in light of present practices. Methods: We searched the literature to address each major screening criterion (disease, test, treatment, program requirements) necessary to support preschool vision screening for amblyopia. We also reappraised papers cited in two systematic reviews related to the impact of vision screening. The Chief Medical Officer of Health of each province/territory was sent a short survey asking whether there currently was a Public Health preschool vision screening program in place and if so, for specifics about the program. Results: An EBPH approach to the literature with respect to the criteria for screening and available intervention studies support amblyopia screening by Public Health. There is a public health divide in amblyopia screening practice in Canada; while some provinces maintain organized programs, others have chosen to delegate the task to other professionals, without a concurrent surveillance function to monitor disparities in uptake. Conclusions: Amblyopia deserves attention from Public Health. Efforts should be made to maintain existing programs, and provinces without organized screening programs should reconsider their role in the prevention of inequities with regard to preventable blindness in Canadian children.

Screening for Amblyopia

Screening for Amblyopia

Efficacy of a Web-Based Intervention to Improve and Sustain Knowledge and Screening for Amblyopia in Primary Care Settings

To evaluate the efficacy of a physician-targeted website to improve knowledge and self-reported behavior relevant to strabismus and amblyopia ("vision") in primary care settings. Eligible providers (filing Medicaid claims for at least eight well-child checks at ages 3 or 4 years, 1 year before study enrollment), randomly assigned to control (chlamydia and blood pressure) or vision groups, accessed four web-based educational modules, programmed to present interactive case vignettes with embedded questions and feedback. Each correct response, assigned a value of +1 to a maximum of +7, was used to calculate a summary score per provider. Responses from intervention providers (IPs) at baseline and two follow-up points were compared to responses to vision questions, taken at the end of the study, from control providers (CPs). Most IPs (57/65) responded at baseline and after the short delay (within 1 hour after baseline for 38 IPs). A subgroup (27 IPs and 42 CPs) completed all vision questions after a long delay averaging 1.8 years. Scores from IPs improved after the short delay (median score, 3 vs. 6; P = 0.0065). Compared to CPs, scores from IPs were similar at baseline (P = 0.6473) and higher after the short-term (P < 0.0001) and long-term (P < 0.05) delay. Significant improvements after the short delay demonstrate the efficacy of the website and the potential for accessible, standardized vision education. Although improvements subsided over time, the IPs' scores did not return to baseline levels and were significantly better compared to CPs tested 1 to 3 years later.

The potential cost-effectiveness of amblyopia screening programs.

To estimate the incremental cost-effective-ness of amblyopia screening at preschool and kindergarten, the costs and benefits of three amblyopia screening scenarios were compared to no screening and to each other: (1) acuity/stereopsis (A/S) screening at kindergarten, (2) A/S screening at preschool and kindergarten, and (3) photoscreening at preschool and A/S screening at kindergarten. A probabilistic microsimulation model of amblyopia natural history and response to treatment with screening costs and outcomes estimated from two state programs was programmed. The probability was calculated that no screening and each of the three interventions were most cost-effective per incremental quality-adjusted life year (QALY) gained and case avoided. Assuming a minimal 0.01 utility loss from monocular vision loss, no screening was most cost-effective with a willingness to pay (WTP) of less than $16,000 per QALY gained. A/S screening at kindergarten alone was most cost-effective at a WTP between $17,000 and $21,000. A/S screening at preschool and kindergarten was most cost-effective at a WTP between $22,000 and $75,000, and photoscreening at preschool and A/S screening at kindergarten was most cost-effective at a WTP greater than $75,000. Cost-effectiveness substantially improved when assuming a greater utility loss. All scenarios were cost-effective when assuming a WTP of $10,500 per case of amblyopia cured. All three screening interventions evaluated are likely to be considered cost-effective relative to many other potential public health programs. The choice of screening option depends on budgetary resources and the value placed on monocular vision loss prevention by funding agencies.

What is vision screening? And more importantly, what is it not?

Summary: The history of screening for amblyopia, strabismus and refractive error has been well publicised and described.1,2 Despite recommendations from the UK National Screening Committee (NSC)3 and Hall Report4 for screening to be offered at to all 4- to 5-year-olds, variation in what is offered, and by whom, remains an ongoing issue. The consequences of this are discussed.

Comparing a traditional single optotype visual acuity test with a computer-based visual acuity test for childhood amblyopia vision screening: a pilot study

Objective: To investigate the effectiveness of a traditional flip-chart optotype test, the Sheridan Gardiner test (SGT), in measuring visual acuity and detecting amblyopia, compared with a free, computer-based test (CBT), LazyeyeTest.org. Design: Prospective, masked, cross-over study. Participants: Seventy kindergarten-aged children from a downtown Toronto elementary school enrolled in the Kids2See vision screening program. Methods: Visual acuity in the children was measured monocularly using both tests. The visual acuity results, number of referrals, and outcomes of referrals were compared, as was the usability from the perspective of the child and the vision screener. Results: The children were more likely to score low visual acuity values with the CBT, a result predicted by the existence of crowding bars on the CBT's optotypes. The CBT referred an extra 5 children than the SGT, and of the 4 who saw an ophthalmologist 2 had amblyopia. The SGT referred one child not referred by the CBT. The Cohen's kappa coefficient was 0.67 and the difference in referral rates was not significant ( p = 0.13). Relative to the SGT, the sensitivity of the CBT was 88%, specificity was 92%, positive predictive value was 58%, and negative predictive value was 98%. The CBT appeared to be easier and more efficient to administer, more stimulating, and was preferred by the children. Conclusions: Replacing the SGT with LazyeyeTest.org would increase the efficiency and likely the sensitivity of amblyopia screening. Further research is warranted to confirm the outcomes and to determine if the CBT can be administered accurately by lay screeners.

Detecção de ambliopia, ametropias e fatores ambliogênicos em comunidade assistida por Programa da Saúde da Família no Rio de Janeiro, Brasil

OBJETIVOS: Determinar a prevalencia dos fatores ambliogenicos e ambliopia na area adscrita do Programa Saude da Familia (PSF) da Lapa (RJ) e, estimar na mesma area a sensibilidade e especificidade entre metodos de medida de acuidade visual (tabelas ETDRS e LEA) em criancas pre-escolares. METODOS: Estudo transversal de 93 criancas entre tres a seis anos da area adscrita do PSF Lapa, RJ. Todas as criancas foram submetidas a avaliacao oftalmologica completa que incluiu: anamnese dirigida, ectoscopia, medida da acuidade visual com tabela de ETDRS e LEA de forma duplo cega, reflexo vermelho, teste de Titmus, refracao objetiva sob cicloplegia, refracao subjetiva, avaliacao da motilidade ocular, biomicroscopia do segmento anterior, fundoscopia sob midriase. Os dados foram coletados na Policlinica Ronaldo Gazolla, da Universidade Estacio de Sa. RESULTADOS: A prevalencia dos fatores ambliogenicos foi encontrada e distribuida em: 8,4 % de estrabismo; 11,86% de anisometropia e 15,2% de ametropia. O teste de acuidade visual ETDRS apresentou sensibilidade de 100% e especificidade de 18% para deteccao de ambliopia. O teste de acuidade visual LEA apresentou sensibilidade de 100% e especificidade de 30,9% para deteccao de ambliopia. CONCLUSAO: Ambas tabelas ETDRS e LEA podem ser usadas para a triagem de ambliopia porque tiveram 100% de sensibilidade. A especificidade foi maior para a tabela LEA. Porem ainda em nivel baixo. Portanto, ha necessidade da complementacao com o exame oftalmologico completo para confirmar e ratificar a presenca de fatores ambliogenicos em pacientes triados positivamente. A triagem visual feita pelos Agentes Comunitarios de Saude pode identificar criancas com disturbios visuais, referenciando para exame oftalmologico completo; em um grupo etario onde a resolucao dos problemas visuais se apresenta como prioridade. O Programa de Saude da Familia pode ser utilizado para avaliar o estado de visao das criancas brasileiras e seria util que essa avaliacao fosse um marcador estatistico do SUS.

Rotterdam AMblyopia Screening Effectiveness Study: Detection and Causes of Amblyopia in a Large Birth Cohort

PURPOSE. The Dutch population-based child health monitoring program includes regular preverbal (age range, 1-24 months) and preschool (age range, 36-72 months) vision screening. This study is on the contribution of an organized vision screening program to the detection of amblyopia. METHODS. A 7-year birth cohort study of 4624 children was started in 1996/1997 in Rotterdam. Vision screening data were obtained from the child screening centers. Treating orthoptists working at the regional ophthalmology departments provided information about diagnosis and treatment. The diagnosis was reviewed by two experts. The parents provided additional information on their child's eye history through written questionnaires and telephone interviews. At age 7 years, the children underwent a final examination by the study orthoptists. RESULTS. Of the 3897 children still living in Rotterdam by 2004, 2964 (76.1%) underwent the final examination. Amblyopia was diagnosed in 100 (3.4%) of these (95% CI, 2.7-4.0). At age 7, 23% had visual acuity >0.3 logMAR. Amblyopia was caused by refractive error (n = 42), strabismus (n = 19), combined-mechanism (n = 30), deprivation (n = 7), or unknown (n = 2). Eighty-three amblyopia cases had been detected before age 7. Amblyopia detection followed positive results in vision screening in 56 children, either preverbal (n = 15) or preschool (n = 41). Twenty-six other amblyopes were self-referred (n = 12, before a first positive screening test), especially strabismic or combined-mechanism amblyopia; data were uncertain for one other positively screened amblyopic child. Amblyopia remained undetected until age 7 due to unsuccessful referral (n = 4, three with visual acuity >0.3 logMAR at age 7) or false-negative screening (n = 13). CONCLUSIONS. Most cases of amblyopia were detected by vision screening with visual acuity measurement. Preverbal screening contributed little to the detection of refractive amblyopia.

Assessment of a modification of Brückner′s test as a screening modality for anisometropia and strabismus

Background:Current amblyopia screening methods are not cost effective.Aim:To evaluate the diagnostic capability of a modified Brückner test (MBT) for amblyopiogenic risk factors.Materials and Methods:We applied the MBT using the streak retinoscope to identify anisometropia and strabismus by noting an inter-ocular difference in movement and glow, from children who failed 6/9 Snellen on community vision screening, followed by comprehensive eye examination.Statisitics:Data were analyzed by 2 × 2 tables for diagnostic test parameters (95% CI).Results:From 7998 children vision-screened, 392 failed 6/9 VA and were referred. Since 34 failed to reach the centers, and 15 were excluded due to poor/ no glow, data from 343 was analyzed. The prevalence of anisometropia of 0.5D was 17%, of 1D was 11% and of strabismus 5%. For the MBT the accuracy was ≥ 90% (95%CI 89% to 97%) over the three outcomes. The sensitivity, specificity, NPV and +LR for anisometropia of 0.5D were: 0.57 (0.48, 0.64), 0.97 (0.95, 0.98), 0.92 (0.90, 0.93) and 18 (9.7, 35); for 1D: 0.74(0.60, 0.82), 0.95 (0.94, 0.97), 0.97 (0.95, 0.98) and 16 (9.3, 28); and for strabismus: 0.5 (0.32, 0.66), 0.98 (0.97, 0.98), 0.97 (0.96, 0.98) and 20 (9.1, 42).Conclusion:Our data suggests that the MBT is highly accurate and useful for ruling in anisometropia and strabismus in children who fail 6/9 Snellen. The MBT needs further validation, both by different care givers and on differing populations. It offers an affordable, portable, and clinically useful tool to detect anisometropia and strabismus. We suggest that performing an MBT prior to uniocular retinosocpy should be a routine practice.

Screening for amblyopia and strabismus in children aged 4–5 years: where do we go from here?

The BIOJ is the official journal of the British and Irish Orthoptic Society. The BIOS was founded in 1937. BIOS is a professional and educational body for the UK and Republic of Ireland representing orthoptists. Orthoptics is a world-wide profession, and the BIOS is recognised as being a leader in both education and clinical practice. The BIOJ invites submissions relating to original research, review articles, case reports and scientific letters to the editor in areas related to clinical ocular motility, visual function, amblyopia, binocular vision and strabismus. The journal will accept submissions from a wide variety of disciplines, including orthoptists, optometrists, ophthalmologists, and vision technicians, among others.

Effectiveness of screening preschool children for amblyopia: a systematic review.

BackgroundAmblyopia and amblyogenic factors like strabismus and refractive errors are the most common vision disorders in children. Although different studies suggest that preschool vision screening is associated with a reduced prevalence rate of amblyopia, the value of these programmes is the subject of a continuing scientific and health policy discussion. Therefore, this systematic review focuses on the question of whether screening for amblyopia in children up to the age of six years leads to better vision outcomes.MethodsTen bibliographic databases were searched for randomised controlled trials, non-randomised controlled trials and cohort studies with no limitations to a specific year of publication and language. The searches were supplemented by handsearching the bibliographies of included studies and reviews to identify articles not captured through our main search strategy.ResultsFive studies met the inclusion criteria. Of these, three studies suggested that screening is associated with an absolute reduction in the prevalence of amblyopia between 0.9% and 1.6% (relative reduction: between 45% and 62%). However, the studies showed weaknesses, limiting the validity and reliability of their findings. The main limitation was that studies with significant results considered only a proportion of the originally recruited children in their analysis. On the other hand, retrospective sample size calculation indicated that the power based on the cohort size was not sufficient to detect small changes between the groups. Outcome parameters such as quality of life or adverse effects of screening have not been adequately investigated in the literature currently available.ConclusionPopulation based preschool vision screening programmes cannot be sufficiently assessed by the literature currently available. However, it is most likely that the present systematic review contains the most detailed description of the main limitations in current available literature evaluating these programmes. Therefore, future research work should be guided by the findings of this publication.

Vision screening for amblyopia in childhood

Amblyopia is a reversible deficit of vision that has to be treated within the sensitive period for visual development. Screening programmes have been set up to detect this largely asymptomatic condition and refer children for treatment while an improvement in vision is still possible. The value of such programmes and the optimum protocol for administering them remain controversial. The objective of this review was to evaluate the effectiveness of vision screening in reducing the prevalence of amblyopia. We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2008), MEDLINE (January 1950 to August 2008) and EMBASE (January 1947 to August 2008). The electronic databases were last searched on 15 August 2008. No language restrictions were placed on these searches. No handsearching was done. We planned to analyse data from randomised controlled trials and cluster-randomised trials comparing the prevalence of amblyopia in screened versus unscreened populations. Two authors independently assessed study abstracts identified by the electronic searches. Full text copies of appropriate studies were obtained and, where necessary, authors were contacted. No data were available for analysis and no meta-analysis was performed. Despite the large amount of literature available regarding vision screening no trials designed to compare the prevalence of amblyopia in screened versus unscreened populations were found. The lack of data from randomised controlled trials makes it difficult to analyse the impact of existing screening programmes on the prevalence of amblyopia. The absence of such evidence cannot be taken to mean that vision screening is not beneficial; simply that this intervention has not yet been tested in robust trials. To facilitate such trials normative data on age-appropriate vision tests need to be available and a consensus reached regarding the definition of amblyopia. In addition, the consequences of living with untreated amblyopia have yet to be quantified and a cost-benefit analysis carried out.

Electronic monitoring of occlusion treatment for amblyopia in patients aged 7 to 16 years

Age limits for the prescription of amblyopia treatment have been debated and challenged recently, due to results of studies from ophthalmology and the neurosciences. Lack of knowledge about compliance with prescribed treatment is still a major factor for the uncertainty about the amount of plasticity in the visual system of older children and adolescents. The development of devices for the electronic recording of patching (Occlusion Dose Monitor, ODM) has allowed the collection of objective data about daily occlusion. In a prospective study, occlusion dose rates were recorded continuously during 4 months by means of the ODM developed in the Netherlands [1] in nine amblyopic patients between 7 and 16 years of age who were prescribed between 5 and 7 hours of daily patching. Visual acuity was assessed every 3 to 6 weeks. The electronic monitoring showed objective occlusion between 2 and 6.25 hours/day (mean 4.61 h/d) during the first month and 0 to 6.5 hours/day (mean 3.47 h/d) during the following 3 months of treatment. The total acuity gain in the amblyopic eye amounted to between -0.1 and 0.4 log units (mean 0.19) for crowded optotypes. Differences to initial acuities were statistically significant. The calculated average dose-response relationship (cumulated hours occlusion*0.1/acuity gain) for 4 months of occlusion was 234 hours of occlusion per 0.1 log unit of acuity gain. This study presents for the first time objective treatment and dose response data in amblyopic patients beyond the "classical" treatment age. Electronic monitoring of occlusion and considerable amounts of patching were shown to be feasible. The acuity results indicate that there is a potential for improvement, yet treatment seemed to be less efficient than shown by previous studies in younger patients. Continuation of this research may advance the discussion about age-dependent evidence-based amblyopia treatment, about preschool screening for amblyopia and about plasticity of the visual system.

066 Les programmes de dépistage du glaucome et de l’amblyopie au Royaume Uni – Sont-ils efficaces ?

Screening programmes are public health services that need to be managed at the level of a large population to monitor quality effectively. In the UK, this is carried out by the National Screening Committee (NSC). The first task of the NSC is to use research evidence to identify programmes that do more good than harm; the second is to make policy recommendations regarding those programmes at a reasonable cost to the state. In policy-making, the evidence for screening is often limited, and the presentation will specifically look at the success and failures of glaucoma and amblyopia screening in the UK.

Evaluation of ′vision screening′ program for three to six-year-old children in the Republic of Iran

Background:Since 1996, vision screening of three to six-year-old children is conducted every year in Iran. We present outcomes of project review held in August 2006.Materials and Methods:Kindergarten teachers examined vision by using Snellen's illiterate ‘E’ chart. They used torchlight to detect strabismus. On a repeat test, if either eye had vision <20/30, the child was referred to the optometrist. A pediatric ophthalmologist examined and managed children with strabismus or amblyopia. Provincial managers supervised the screening program. The evaluator team assessed the coverage, yield, quality and feasibility, and cost-effectiveness of vision screening, as well as magnitude of amblyopia, and its risk factors.Result:In 2005, 1.4 million (67%) children were examined in all provinces of Iran. Opticians examined 90,319 (61%) children with defective vision that were referred to them. The prevalence of uncorrected refractive error, strabismus and amblyopia was 3.82% (95% CI 3.79 – 3.85), 0.39% (95% CI 0.38 – 0.40) and 1.25% (95% CI 1.24 – 1.26) respectively. Validity test of 7,768 children had a sensitivity of 74.5% (95% CI 72.7 – 76.3) and specificity of 97.2% (95% CI 96.7 – 97.7). The cost of amblyopia screening was US $ 1.5 per child. While the cost of screening and treating one child with amblyopia was US $ 245.Conclusion:A review of the vision screening of children in Iran showed it with screening and useful exercise and had a yield of 1:21. The coverage of vision screening was low and the management of children with amblyopia, low vision and refractive error needed strengthening.

The clinical effectiveness and cost-effectiveness of screening programmes for amblyopia and strabismus in children up to the age of 4-5 years: a systematic review and economic evaluation

To estimate the cost-effectiveness of screening for amblyopia and strabismus in children aged up to 4-5 years, also identifying the major areas of uncertainty and so inform future research priorities in this disease area. Major electronic databases were searched in January 2006. Systematic literature reviews were undertaken to determine the prevalence and natural history, the screening methods, the effectiveness of treatment options and health-related quality of life issues relating to amblyopia and strabismus. The review of treatment interventions was restricted to high-quality reviews, meta-analyses and guidelines. The data derived from the review informed the structure and implementation of the decision-analytic model. The amblyopia screening model was analysed in detail to estimate the cost and effects of six alternative screening options comprising screening at different ages (3, 4 and 5 years) and using alternative sets of tests (visual acuity testing and the cover tests, with and without autorefraction). The reference case results showed that screening programmes that included autorefraction dominated screening programmes without autorefraction. Analyses based on the cost per case of amblyopia prevented showed screening at either 3 or 4 years prevented additional cases at a low absolute cost (3000-6000 pounds sterling). However, when these results were extrapolated to estimate the cost per quality-adjusted life-year (QALY) gained, the reference case analysis found that no form of screening is likely to be cost-effective at currently accepted values of a QALY. The wide-ranging sensitivity analyses found that the results were robust to most parameter changes. The only parameter that radically affected the results was the utility effect of loss of vision in one eye. No direct evidence of a utility effect was identified and the reference case assumed no effect. When a small effect is assumed (a reduction in utility of 2%), the incremental cost per QALY gained becomes extremely attractive for screening at both 3 and at 4 years. The expected value of perfect information was shown to be large when the unilateral vision loss utility parameter was allowed to vary, but not when it was kept constant at zero. The results show that the cost-effectiveness of screening for amblyopia is dependent on the long-term utility effects of unilateral vision loss. There is limited evidence on any such effect, although our subjective interpretation of the available literature is that the utility effects are likely to be minimal. Any utility study investigating such effects would need to be careful to avoid introducing bias. The reference case model did not represent potential treatment-related utility effects, primarily due to an increased probability of treated children being bullied at school. The evidence indicates that this may be a problem, and additional sensitivity analyses show that small utility decrements from bullying would improve the cost-effectiveness of early screening significantly. A prospective study of the utility effects of bullying would usefully inform the analysis, although such a study would need to be carefully planned in order to distinguish whether the overall incidence of bullying decreases with reduced school-age treatment, or whether it is displaced to other children.

Risk of bilateral visual impairment in individuals with amblyopia: the Rotterdam study

Background:The excess risk of bilateral visual impairment (BVI; bilateral visual acuity <0.5) among individuals with amblyopia is an argument for screening for amblyopia, but data are scarce.Methods:The risk was estimated...

Amblyopia screening

&lt;zakljucak&gt; S obzirom na neujednacenu pokrivenost zemlje oftamoloskom sluzbom, resurse i edukaciju trebalo bi usmeriti, pre svega, na pedijatre i lekare opste medicine koji su ukljuceni u pregled ociju dece. Takodje, bila bi potrebna standardizacija optotipa i protokola ispitivanja. Trebalo bi poboljsati i informisanost roditelja putem stampanog materijala koji bi trebalo da bude dostupan, kako u primarnoj tako i u sekundarnoj i tercijarnoj zdravstvenoj zastiti.

Screening amblyopia of preschool children with uncorrected vision and stereopsis tests in Eastern Taiwan

AIMS OR PURPOSE: Screening for amblyopia at earliest age is important for early treatment and better prognosis. This study aimed at evaluating the validity of uncorrected distant and near visual acuity and random dot stereopsis for screening amblyopia. METHODS; In Eastern Taiwan, population-based screen tests were performed for children at age from 3 to 6 years. The tests included uncorrected distant and near visions and random dot stereopsis (300 s) test. The screen performers were registered nurses of local public health service posts. The golden standards of the tests were the results of examination by the ophthalmologists. Including Hans and aboriginal Taiwanese, 5232 children were included. Screened by distance visual acuity with different cutoffs and near visual acuity, 10.3, 30.3 and 8.2% children were abnormal. Screened by random dot, only 2% children were abnormal. By a senior ophthalmologist, 115 amblyopic children were diagnosed amblyopic. The sensitivities of distance visual acuity with low/high cutoff and near visual acuity were 74.7/84.8 and 49.4%, whereas that of the NTU random dot stereogram was 20.5%. Simultaneous testing of either two of the three tests improved the sensitivity. Screening for amblyopia by the local nurses using the visual acuity tests or random dot stereopsis test alone does not display a high sensitivity. Simultaneous testing of distant visual acuity and stereopsis test elevate the sensitivity and preserve the specificity.