Critical appraisal of Australian and New Zealand paediatric vision screening clinical practice guidelines using the AGREE II tool.

CLINICAL RELEVANCE: Vision disorders in children impact health-related quality of life, with early detection and intervention improving outcomes and educational performance. Eye health professionals should be aware of paediatric vision screening guidelines and their development to understand the components of local programmes and the differences in sensitivity and specificity between protocols. BACKGROUND: High-quality clinical practice guidelines (CPGs) for vision screening enable the early detection of common vision disorders; however, they require rigorous development to ensure optimal accuracy in detecting vision disorders, enabling timely interventions. This study evaluated the quality of available vision screening CPGs on vision screening of children in Australia and New Zealand. METHODS: A systematic search of academic databases, guideline databases, professional associations and Google search engines was conducted to identify relevant paediatric vision screening CPGs. Four independent reviewers used the Appraisal of Guidelines, Research and Evaluation (AGREE II) instrument to assess the quality of individual guidelines and scores were aggregated and reported as the percentage of the total possible score across the six AGREE II domains: scope and purpose, stakeholder involvement, rigour of development, clarity of presentation, applicability, and editorial independence. RESULTS: Initial 2,999 items were evaluated, with seven guidelines included. AGREE-II quality score agreement ranged from 43.3% to 95.8%. All guidelines scored >60.0% in the scope and purpose, however, most had poor scores of <26.5% in the rigour of development and <3.3% in editorial independence domains. All guidelines recommended screening using measures of habitual distance vision. CONCLUSION: Of the guidelines developed for use in Australia and New Zealand, most guidelines scored poorly when assessed against the AGREE II tool, because of lack of editorial independence and rigour of development. Paediatric vision screening guidelines should prioritise systematic review of literature to inform practice and include statements regarding competing interests.

Delayed melatonin circadian timing, lower melatonin output, and sleep disruptions in myopic, or short-sighted, children.

STUDY OBJECTIVES: This study investigated the differences in melatonin circadian timing and output, sleep characteristics, and cognitive function in myopic and non-myopic (or emmetropic) children, aged 8-15 years. METHODS: Twenty-six myopes (refractive error [mean ±â€…standard error mean] -2.06 ±â€…0.23 diopters) and 19 emmetropes (-0.06 ±â€…0.04 diopters), aged 11.74 ±â€…2.31 years were recruited. Circadian timing was assessed using salivary dim-light melatonin onset (DLMO), collected half-hourly for 7 hours, beginning 5 hours before and finishing 2 hours after individual average sleep onset in a sleep laboratory. Nocturnal melatonin output was assessed via aMT6s levels from urine voids collected from 05:30 pm to 8:00 am the following morning. Actigraphy-derived objective sleep timing were acquired for a week prior to the sleep laboratory visit. Cognitive assessments of sustained attention (using psychomotor vigilance task [PVT]) and working memory (using digit spans) were performed on the night of sleep laboratory. RESULTS: Myopic children (9:07 pm ±â€…14 minutes) exhibited a DLMO phase-delay of 1 hour 8 minutes compared to emmetropes (7:59 pm ±â€…13 minutes), p = 0.002. aMT6s melatonin levels were significantly lower among myopes (18.70 ±â€…2.38) than emmetropes (32.35 ±â€…6.93, p = 0.001). Myopes also exhibited significantly delayed sleep onset, delayed wake-up time, poor and reduced sleep, and more evening-type diurnal preference than emmetropes (all p < 0.05). Finally, myopes showed a slower reaction time in the PVT (p < 0.05), but not digit span tasks at night. CONCLUSIONS: These findings suggest a potential association between circadian rhythm dysfunction and myopia in children.

Developing culturally safe education practices in optometry schools across Australia and Aotearoa New Zealand.

Access to culturally safe health services is a basic human right, however through the lasting effects of colonisation, oppression, and systemic racism, the individual and community health of Indigenous peoples in Australia and Aotearoa New Zealand have been severely impacted. The Aboriginal and Torres Strait Islander Health and Cultural Safety Strategy of the Australian Health Practitioners Regulation Agency, and the Standards of Cultural Competence and Cultural Safety of the Optometrists and Dispensing Opticians Board of New Zealand, recognise the importance of access to safe health care for Aboriginal, Torres Strait Islander and Maori patients, which encompasses both clinical competency and cultural safety. Universities have an ongoing responsibility to ensure their learning and teaching activities result in graduates being able to provide culturally safe practice. This article highlights the emergence of culturally safe practices in the Australian and Aotearoa New Zealand optometry curricula over the last five years incorporating Indigenous ways of knowing, being and doing into the curricula, understanding the local Indigenous histories and contexts, the adoption of online cultural education modules, and clinical placement partnerships with local Indigenous communities. Whilst there is still much work to do to achieve the goal of graduating culturally safe optometrists, this paper focuses on features that enable or impede progress in the development of culturally safe practices within the optometry programmes to improve eye health equity for Indigenous recognise the diversity of Indigenous cultures across Australia and NZ.

The safety and tolerability of levodopa eye drops for the treatment of ocular disorders: A randomized first-in-human study.

Myopia is the leading cause of low vision worldwide and can lead to significant pathological complications. Therefore, to improve patient outcomes, the field continues to develop novel interventions for this visual disorder. Accordingly, this first-in-human study reports on the safety profile of a novel dopamine-based ophthalmic treatment for myopia, levodopa/carbidopa eye drops. This phase I, first-in-human, monocenter, placebo-controlled, double-blind, paired-eye, multidose, randomized clinical trial was undertaken in healthy adult males aged 18-30 years (mean age 24.9 ± 2.7) at the University of Canberra Eye Clinic, Australia. Participants were randomly assigned to receive either a low (1.4 levodopa:0.34 carbidopa [µmoles/day], n = 14) or standard dose (2.7 levodopa:0.68 carbidopa [µmoles/day], n = 15) of levodopa/carbidopa eye drops in one eye and placebo in the fellow eye once daily for 4 weeks (28 days). Over this 4-week trial, and after a 4-month follow-up visit, levodopa/carbidopa treatment had no significant effect on ocular tolerability and anterior surface integrity, visual function, ocular health, refraction/ocular biometry, and did not induce any non-ocular adverse events. These results indicate that topical levodopa/carbidopa is safe and tolerable to the eye, paving the way for future studies on the efficacy of this novel ophthalmic formulation in the treatment of human myopia. The findings of this study have implications not only for the treatment of myopia, but in a number of other visual disorders (i.e., amblyopia, diabetic retinopathy, and age-related macular degeneration) in which levodopa has been identified as a potential clinical intervention.

Relationship between visual and neurodevelopmental measures at 2 years with visual acuity and stereopsis at 4.5 years in children born at risk of neonatal hypoglycaemia.

PURPOSE: Mild to moderate vision loss affects many children and can negatively impact a child's early literacy and academic achievement. Nevertheless, there is no consensus on which factors present in early childhood indicate the need for long-term ophthalmic follow up, particularly in children with a history of perinatal adversity. This study identified the relationship between visual, cognitive, motor and demographic factors at 2 years of age and visual acuity (VA) and stereoacuity at 4.5 years of age. METHODS: Five hundred sixteen children identified as being at risk of neonatal hypoglycaemia were recruited soon after birth. At 2 years of age, binocular VA, stereoacuity and non-cycloplegic refraction were measured and a clinical neuro-developmental assessment with the Bayley Scales of Infant Development III (BSID-III) was conducted by a trained examiner. Monocular VA and stereoacuity were measured at 4.5 years of age. RESULTS: Three hundred twenty-eight children completed both the 2 and 4.5 year vision and neurodevelopmental assessments. Multiple linear regression showed oblique astigmatism and motor function at 2 years were significantly associated with VA at 4.5 years of age, while spherical equivalent refraction, motor scores and stereoacuity at 2 years were significantly associated with stereoacuity at 4.5 years of age. BSID-III motor scores had the best sensitivity (81.8%) and specificity (51.5%) for identifying impaired stereoacuity at 4.5 years. However, all measures at 2 years were poorly associated with VA at 4.5 years old. CONCLUSION: Vision and neurodevelopmental measures at 2 years were poorly associated with visual function at 4.5 years of age. However, lower scores on tests of motor function at 2 years may be associated with vision abnormalities, particularly reduced stereopsis, at 4.5 years of age and referral for comprehensive vision assessment for these children may be warranted.

The repeatability and reproducibility of four techniques for measuring horizontal heterophoria: Implications for clinical practice

Purpose: Convergence insufficiency, the most common binocular vision anomaly, is characterised by a receded near point of convergence and an exophoria which is at least 4 prism dioptres (Δ) larger at near than at distance. However, the repeatability of standard heterophoria measures are poorly understood. This study assessed the ability of four common heterophoria tests to detect differences of 4Δ by evaluating the inter- and intra-examiner variability of the selected techniques. Methods: Distance and near horizontal heterophorias of 20 visually-normal adults were measured with the alternating prism cover test, von Graefe prism dissociation, Howell Card and Maddox Rod by two examiners at two separate visits using standardised instructions and techniques. We investigated inter- and intra-examiner variability using repeatability and reproducibility indices, as well as Bland-Altman analysis with acceptable limits of agreement defined as ±2Δ. Results: The Howell card test had the lowest intra-examiner variability at both distance and near, as well as the best 95% limits of agreement (±1.6Δ for distance and ±3.7Δ for near). Inter-examiner reproducibility results were similar, although at near the alternating prism cover test had better repeatability (1.1Δ, 95% confidence intervals −1.1Δ to 4.0Δ) than the Howell card (1.4Δ, 95% confidence intervals −1.9Δ to 5.9Δ). Conclusion: The low repeatability of many standard clinical heterophoria tests limits the ability to reliably detect a 4Δ difference. The Howell Card provided the most repeatable and reproducible results indicating that this technique should be used to detect small changes in heterophoria magnitude and direction. (AU)

Vision screening in New Zealand pre-school children: Is it equitable?

AIM: This study aimed to investigate the variability by ethnicity, socio-economic status and location in coverage and testability of the universal B4 School Check vision screening in children aged 4-5 years in New Zealand. METHODS: Aggregated data from 1 July 2011 to 30 June 2015 were sourced from the Statistics New Zealand Integrated Data Infrastructure. Sourced data were attendance at vision screening and record of visual acuity measurement stratified by ethnicity, socio-economic status and region. Children who attended screening were compared with the eligible population (n = 252 279) to calculate coverage. Testability was determined by comparing the children with a recorded visual acuity measurement in each eye with those who attended screening. RESULTS: Overall vision screening coverage was 89.5% and testability was 97.8%. Ethnic differences were evident for coverage (85.7% in Pacific children, 92.5% in European children) and testability (96.4% in Maori children, 98.4% in European children). Socio-economic differences were also observed for coverage (86.4% in most deprived areas, 92.4% in least deprived), testability (most deprived 96.3%, least deprived 98.7%) and by region (coverage range of 80.4-96.4% and testability range of 93.2-99.3%). CONCLUSIONS: Significant disparities exist in vision screening coverage and testability for New Zealand pre-school children. Equity-focused initiatives are required to improve outcomes for children from Maori and Pacific families, and those from households in lower socio-economic areas. Understanding region-specific challenges and successes could support more equitable access to vision screening between regions. Further research is required to determine sources of inequities and to investigate interactions between ethnicity, socio-economic status and location.

Diagnostic accuracy of the Parr vision test, single crowded Lea symbols and Spot vision screener for vision screening of preschool children aged 4-5 years in Aotearoa/New Zealand.

PURPOSE: Preschool children in New Zealand undergo vision screening to detect amblyopia at 4-5 years of age. The current test, the Parr vision test, does not meet international visual acuity chart guidelines and has not been validated against other commonly used paediatric vision tests. New Zealand vision screening protocols are also not targeted for detecting other eye conditions such as uncorrected refractive error, which may affect school performance. We compared the Parr vision test with the single crowded Lea symbols and the Spot vision screener for detecting ocular pathology, refractive error and amblyopic risk factors in preschool children. METHODS: A cross-sectional diagnostic accuracy study recruited children aged 4-5 years via convenience sampling from the University of Auckland Optometry Clinic and through primary schools in Auckland, New Zealand. Participants received vision screening with the three different instruments administered by a lay screener. Comprehensive eye examinations were completed by a paediatric optometrist to determine the presence of vision disorders. RESULTS: Of 197 children who received a comprehensive eye examination, 14 (7.1%) had amblyopic risk factors and 43 (21.8%) had significant refractive error (15.7% with astigmatism, 9.1% with hyperopia). The sensitivity for detecting any ocular condition did not differ significantly between the tests (50.0% for Parr, 43.5% for Lea, 42.5% for Spot). Specificity was significantly lower for the Parr vision test (80.8%) than for the Lea symbols (93.4%) and Spot vision screener (98.0%). Adding the Spot vision screener to measurements of visual acuity significantly improved sensitivity in detecting any ocular condition with the Parr vision test (67.5% for Parr/Spot vs 50% for Parr alone), but not with the Lea symbols (52.5% for Lea/Spot vs 43.5% for Lea alone). CONCLUSION: The sensitivity of the Parr vision test for detecting ocular conditions in preschool children does not vary significantly from that achieved by the Lea symbols or the Spot vision screener. However, current New Zealand vision screening protocols could be improved by expanding the target conditions to include significant refractive error and incorporating the use of the Spot vision screener to increase the accuracy with which children with refractive error are identified. Future research should include longitudinal studies to determine the effect of preschool vision screening on later ocular and academic outcomes.

The repeatability and reproducibility of four techniques for measuring horizontal heterophoria: Implications for clinical practice.

PURPOSE: Convergence insufficiency, the most common binocular vision anomaly, is characterised by a receded near point of convergence and an exophoria which is at least 4 prism dioptres (Δ) larger at near than at distance. However, the repeatability of standard heterophoria measures are poorly understood. This study assessed the ability of four common heterophoria tests to detect differences of 4Δ by evaluating the inter- and intra-examiner variability of the selected techniques. METHODS: Distance and near horizontal heterophorias of 20 visually-normal adults were measured with the alternating prism cover test, von Graefe prism dissociation, Howell Card and Maddox Rod by two examiners at two separate visits using standardised instructions and techniques. We investigated inter- and intra-examiner variability using repeatability and reproducibility indices, as well as Bland-Altman analysis with acceptable limits of agreement defined as ±2Δ. RESULTS: The Howell card test had the lowest intra-examiner variability at both distance and near, as well as the best 95% limits of agreement (±1.6Δ for distance and ±3.7Δ for near). Inter-examiner reproducibility results were similar, although at near the alternating prism cover test had better repeatability (1.1Δ, 95% confidence intervals -1.1Δ to 4.0Δ) than the Howell card (1.4Δ, 95% confidence intervals -1.9Δ to 5.9Δ). CONCLUSION: The low repeatability of many standard clinical heterophoria tests limits the ability to reliably detect a 4Δ difference. The Howell Card provided the most repeatable and reproducible results indicating that this technique should be used to detect small changes in heterophoria magnitude and direction.

The effect of induced blur on the Beery-Buktenica developmental test of visual-motor integration and its supplemental tests.

BACKGROUND: The Beery-Buktenica Test of Visual-Motor Integration (Beery VMI) is a commonly used standardized test of visual-motor integration. Performance on the test is related to academic achievement, but the effect of reduced visual acuity on test results is unknown. This study determined the visual acuity demand and the spacing of the test forms for the Beery VMI and its supplemental tests and investigated the effect of induced optical blur on test results in both adults and children. METHODS: The overall size and critical detail size of each form and the distance between the center of each form and its adjacent crowding source were measured. The visual acuity demand and angular separation of forms were calculated. Two groups of participants (adults aged ≥18 years [n = 19] and children aged 7-12 years [n = 20]) completed four sessions in which they performed the Beery VMI and the supplemental tests under different blur conditions (habitual near correction, monocular spherical blur, binocular spherical blur and binocular astigmatic blur) in a randomized order. RESULTS: Stroke width, overall form size and box size remained constant throughout the Beery VMI, whereas these reduced with increasing difficulty for the supplemental tests. Reduced near visual acuity from simulated blur resulted in reduced mean scores for the Beery VMI and its supplemental tests, compared with habitual near vision in both adults and children. Binocular spherical blur had the most detrimental effect (p<0.001), followed by binocular astigmatic blur (p<0.001) then monocular spherical blur (p = 0.022). CONCLUSIONS: In individuals with uncorrected spherical or astigmatic ametropia, reduced scores on the Beery VMI and its supplemental tests may be due to impaired near visual acuity and not reflect reduced visual-motor abilities. This highlights the importance of excluding reduced near visual acuity as a cause of reduced performance before diagnosing impairment and initiating treatment strategies for visual-motor integration.

The prevalence of refractive error and visual impairment among New Zealand children in a community with significant socioeconomic disadvantage: is current preschool vision screening effective?

AIM: To examine the prevalence of refractive error and visual impairment and evaluate the efficacy of B4 School Check (B4SC) vision screening, in a cohort of predominantly New Zealand Maori and Pacific children from a community with socioeconomic disadvantage. METHOD: A cross-sectional investigation of children in the Welcome-to-School study. Participants received a comprehensive eye examination at six to seven years of age. Refractive error and amblyopia were identified and compared with B4SC vision screening results. RESULTS: One-hundred and fourteen children were assessed: 21.9% Maori, 57.9% Pacific and 20.2% Other. Over 30% of children had significant refractive error. Eighty-nine percent received a B4SC; 26.3% of children who passed the B4SC had significant refractive error. Seven children (6.1%) had amblyopia risk factors: none passed the B4SC, four were referred, one was identified for rescreening and two were not screened. CONCLUSION: Refractive errors were common in this cohort. For those screened, the B4SC was effective at identifying children with amblyopia risk factors but poor at detecting refractive errors potentially affecting academic performance. The efficacy of the programme was limited by the number of children screened, inequity of screening and the mismatch between the aims of the vision screening test and the overall rationale for the B4SC.

Multiple Tools Are Needed for the Detection of Prenatal Alcohol Exposure: Findings From a Community Antenatal Setting.

BACKGROUND: Although the toxic effects of prenatal alcohol exposure (PAE) on children are well established, there is emerging evidence about the dynamics and associated demographics of drinking patterns across pregnancy, with risky drinking more likely to take place in the period before pregnancy awareness. This study investigated the use of complementary measurement tools in the understanding of alcohol use across pregnancy and reports on the rates and patterns of alcohol use in a community antenatal setting. METHODS: Data on alcohol consumption before and after awareness of pregnancy were collected via multiple measurement tools: anonymous lifestyle questionnaire, TWEAK (Tolerance, Worried, Eye-opener, Amnesia, K/Cut down) screener questionnaire, and Substance Use Inventory interviews across multiple pregnancy timepoints. Additionally, phosphatidylethanol (PEth), a direct biomarker of alcohol metabolism, collected from newborns' dried blood spot cards, was analyzed. RESULTS: The TWEAK screener was more likely to identify risky drinking behavior than the lifestyle questionnaire. When pregnancy was unplanned, women were more likely to find out they are pregnant significantly later (p < 0.001) and consume alcohol at moderate-heavy levels (p = 0.03), prolonging the risk to the fetus. There was an association between maternal self-reported alcohol use on the lifestyle questionnaire and Substance Use Inventory interviews, but no association between maternal reports of alcohol use and PEth results (p = 0.72). Women self-reported moderate-heavy alcohol use in early pregnancy only and a positive PEth screen indicated PAE in late pregnancy, suggesting that these methods may identify different groups of women. CONCLUSIONS: Multiple measurement tools and methods are needed to identify PAE at different points across pregnancy. Prospective sensitive interviewing is better suited to detecting PAE in early pregnancy, but not later when social desirability bias is stronger, and the use of an objective biomarker, such a PEth, may be useful for identifying the risk of PAE in late pregnancy.

The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review.

The green tea amino acid, L-theanine (L-THE) is associated with several health benefits, including improvements in mood, cognition and a reduction of stress and anxiety-like symptoms. This systematic review evaluated the effect of pure L-THE intake, in the form of orally administered nutritional supplements, on stress responses and anxiety levels in human randomised controlled trials. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, 9 peer-reviewed journal articles were identified where L-THE as a supplement was compared to a control. Our findings suggest that supplementation of 200-400 mg/day of L-THE may assist in the reduction of stress and anxiety in people exposed to stressful conditions. Despite this finding, longer-term and larger cohort clinical studies, including those where L-THE is incorporated into the diet regularly, are needed to clinically justify the use of L-THE as a therapeutic agent to reduce stress and anxiety in people exposed to stressful conditions.

Evaluation of vision screening of 5-15-year-old children in three Tongan schools: comparison of The Auckland Optotypes and Lea symbols.

BACKGROUND: Comprehensive vision screening programmes for children are an important part of public health strategy, but do not exist in many countries, including Tonga. This project set out to assess: (1) the functional vision of children attending primary schools in Tonga and (2) how a new recognition acuity test (The Auckland Optotypes displayed on a tablet computer) compares to use of a standardised eye chart in this setting. METHODS: Children from three Tongan primary schools were invited to participate. Acuity testing was conducted using a standardised recognition acuity chart (Lea symbols) and the tablet test displaying two formats of The Auckland Optotypes. Measures of ocular alignment, stereo acuity and non-cycloplegic photorefraction were also taken. RESULTS: Parents of 249 children consented to participate. One child was untestable. Only 2.8 per cent of testable children achieved visual acuity worse than 0.3 logMAR in the weaker eye. Results from the Spot Photoscreener suggested that no children had myopia or hyperopia, but that some children had astigmatism. The tablet test was practical in a community setting, and showed ±0.2 logMAR limits of agreement with the Lea symbols chart. CONCLUSION: The sample of children in Tongan primary schools had good functional vision. A modified version of the tablet acuity test is a promising option for vision screening in this context.

Geographic distribution of eye-care practitioners in Aotearoa/New Zealand: implications for future eye health workforce.

BACKGROUND: The New Zealand Ministry of Health provides funding for the delivery of health care across regions via 20 District Health Boards. Funding includes the subsidisation of therapeutic pharmaceutical agents/drugs. The distribution of optometrists and ophthalmologists across the regions was investigated to understand the accessibility of eye care in New Zealand. Changes made to the optometrists' scope of practice in 2005 and in 2014 increased the range of drugs that suitably qualified optometrists could prescribe. Therefore, the distribution of optometrists authorised to prescribe drugs and those not authorised to prescribe drugs was also investigated. METHODS: Information from the New Zealand Optometrists and Dispensing Opticians Board register and information from the Medical Council's website were used to create a database of ophthalmic practitioners and their locations. The χ2 goodness-of-fit test was carried out to determine whether the distribution of the number of practitioners across the regions was in proportion to the population of the regions. RESULTS: Ophthalmologists were distributed across the regions in proportion to the regional population size. However, optometrists were concentrated in Auckland and other regions with high populations. Optometrists authorised to prescribe drugs comprised over 74 per cent of optometrists and were the majority of optometrists in most regions. Many of the regions with populations less than 200,000 had high population-to-practitioner ratios, indicating that they may not have sufficient numbers of ophthalmic practitioners in order to provide for the ocular needs of the community. CONCLUSION: Better distribution of the optometric workforce could make eye care more accessible in many regions of New Zealand.

Student acceptance of e-learning methods in the laboratory class in Optometry.

Today's students have increased expectations for flexible learning options and evidence-based practice resources to be available to support curricular activities. We investigated: (i) the suitability of a static website for teaching ocular anatomy and physiology and an interactive version of the website with quiz and self-assessment activities and (ii) the usefulness of a blended online and in-lab environment to teach in Optometry. We administered a survey to compare responses of optometry students who had access to the interactive website, with those from students from a previous year who used the static version. We examined learning preferences of students in a focus group. Students were positive about the value of the website for their learning and the clarity of the website content. Nevertheless, objective comparison of pass rates for students using the static and interactive websites did not show significant changes. The majority of students commenting on the static website felt they did not get sufficient feedback via the website (67%) compared with only 22% from students who used self-assessments in the interactive website. Interestingly, users of the static website commented that it was perceived as just another resource while users of the interactive website commented on the usefulness of the material to review knowledge before laboratories. In the focus group, students reported they preferred a blended learning over the website alone even by students using the interactive website as they felt the need to revise content with the educator before the test. We conclude that there is acceptance of online learning methods due to the technologically 'savvy' environment of students in the first year of the Optometry programme but there is still dependence on the educator as the main administrator of their learning.

Recognition acuity in children measured using The Auckland Optotypes.

PURPOSE: Sloan letters displayed by the Electronic Visual Acuity (EVA) system are the gold standard for recognition acuity measurement in research settings. However, letters are not always appropriate for children. The Auckland Optotypes (TAO) are a new, open-access set of 10 pictograms available in regular and vanishing formats. We sought to assess feasibility of using both formats of TAO for measuring visual acuity (VA) in children using a Bayesian adaptive staircase, in a community setting. METHODS: We tested 121 children (5-12 years old) with both formats of TAO, a handheld flipchart vision screener (Parr vision test), as well as the gold standard EVA. We measured feasibility of the three comparison tests in three ways. First, using limits of agreement (LoA) with EVA, second, calculating area under the receiver operating characteristic curve (AUC), and finally, investigating trial-by-trial responses. RESULTS: Agreement between tests was within test-retest reliability of EVA measures (LoATAOregular  = ±0.14, LoATAOvanishing  = ±0.15, LoAParr  = ±0.16 logMAR). TAO tests were highly effective at identifying children with vision impairment (AUCTAOregular  = 0.96, AUCTAOvanishing  = 0.95), whereas Parr was less effective (AUCParr  = 0.82). In 5-6 year old children there was an enhanced advantage of TAO (AUCTAOregular  = 0.97, AUCTAOvanishing  = 0.98) over Parr (AUCParr  = 0.75). Although each child completed 16 trials, approximately 10 trials were sufficient to achieve excellent LoA, and six trials sufficient for accurate screening. CONCLUSION: Threshold VA assessment and vision screening are feasible using both vanishing and regular formats of TAO.

Orientation Tuning and Contrast Dependence of Continuous Flash Suppression in Amblyopia and Normal Vision.

Purpose: Suppression in amblyopia may be an unequal form of normal interocular suppression or a distinct pathophysiology. To explore this issue, we examined the orientation tuning and contrast dependence of continuous flash suppression (CFS) in adults with amblyopia and visually normal controls. Methods: Nine patients (mean age, 26.9 ± SD 4.7 years) and 11 controls (mean age, 24.8 ± SD 5.3 years) participated. In the CFS paradigm, spatially one-dimensional noise refreshing at 10 Hz was displayed in one eye to induce suppression of the other eye, and suppression strength was measured by using a grating contrast increment detection task. In experiment 1, noise contrast was fixed and the orientation difference between the noise and the grating was varied. In experiment 2, noise and grating orientations were identical and noise contrast was varied. Results: Suppression patterns varied in both groups. In experiment 1, controls showed consistently orientation-tuned CFS (mean half-height bandwidth, 35.8° ± SD 21.5°) with near-equal strength between eyes. Five of nine patients with amblyopia exhibited orientation-independent CFS. Eight patients had markedly unequal suppression between eyes. Experiment 2 found that increasing the noise contrast to the amblyopic eye may produce suppression of the fellow eye, but suppression remained unequal between eyes. Conclusions: Our data revealed that orientation specificity in CFS was very broad or absent in some patients with amblyopia, which could not be predicted by clinical measures. Suppression was unbalanced across the entire contrast range for most patients. This suggests that abnormal early visual experience disrupts the development of interocular suppression mechanisms.