Search

Background New digital technologies (augmented reality headsets, eye-tracking) may potentially allow for automated assessments of ocular misalignment. Here, we evaluate the feasibility of a novel, open-source strabismus test (“STARE”) as an automated screening tool. Methods Work progressed in 2 phases. In phase 1 (“development”), we used Fresnel prisms to elicit horizontal misalignments of known magnitude (1–40 prism dioptres) in orthotropic controls. In phase 2 (“validation”), we applied the system to adults with an established diagnosis of strabismus, and quantified the ability of the test to distinguish between those with horizontal misalignment and those without. Agreement between the alternate prism cover test measurements and STARE measurements was computed using Bland–Altman plots and product-moment correlation coefficients. Results Seven orthotropic controls and nineteen patients with strabismus were recruited (mean age 58.7 ± 22.4 years). STARE was able to identify the presence of horizontal strabismus with an area under the curve of 1.00 (100% sensitivity and 100% specificity). The mean difference (bias) {95% CI} was 2.1 {−1.8, 9.9} prism dioptres, and the 95% coefficient of repeatability {95% CI} was ±27.9 {14.8, 50.8} prism dioptres. The Pearson correlation between APCT and STARE was r24 = 0.62, P Conclusions STARE shows promise as a simple, automated tool for performing a screening assessment of strabismus. It is a rapid (60 s) test that can be performed using a consumer augmented reality headset with integrated eye-tracking, and might conceivably be used remotely by non-specialists in future as a means of highlighting individuals needing face-to-face specialist care.

Purpose To assess accuracy and adherence of visual field (VF) home monitoring in a pilot sample of patients with glaucoma. Design Prospective longitudinal feasibility and reliability study. Methods Twenty adults (median 71 years) with an established diagnosis of glaucoma were issued a tablet perimeter (Eyecatcher) and were asked to perform 1 VF home assessment per eye, per month, for 6 months (12 tests total). Before and after home monitoring, 2 VF assessments were performed in clinic using standard automated perimetry (4 tests total, per eye). Results All 20 participants could perform monthly home monitoring, though 1 participant stopped after 4 months (adherence: 98% of tests). There was good concordance between VFs measured at home and in the clinic (r = 0.94, P Conclusions Home monitoring of VFs is viable for some patients and may provide clinically useful data.

In instances of asymmetric peripheral vision loss (e.g., glaucoma), binocular performance on simple psychophysical tasks (e.g., static threshold perimetry) is well-predicted by the better seeing eye alone. This suggests that peripheral vision is largely ‘better-eye limited’. In the present study, we examine whether this also holds true for real-world tasks, or whether even a degraded fellow eye contributes important information for tasks of daily living. Twelve normally-sighted adults performed an everyday visually-guided action (finding a mobile phone) in a virtual-reality domestic environment, while levels of peripheral vision loss were independently manipulated in each eye (gaze-contingent blur). The results showed that even when vision in the better eye was held constant, participants were significantly slower to locate the target, and made significantly more head- and eye-movements, as peripheral vision loss in the worse eye increased. A purely unilateral peripheral impairment increased response times by up to 25%, although the effect of bilateral vision loss was much greater (>200%). These findings indicate that even a degraded visual field still contributes important information for performing everyday visually-guided actions. This may have clinical implications for how patients with visual field loss are managed or prioritized, and for our understanding of how binocular information in the periphery is integrated.

Summary: Background: We undertook a Grand Challenges in Global Eye Health prioritisation exercise to identify the key issues that must be addressed to improve eye health in the context of an ageing population, to eliminate persistent inequities in health-care access, and to mitigate widespread resource limitations. Methods: Drawing on methods used in previous Grand Challenges studies, we used a multi-step recruitment strategy to assemble a diverse panel of individuals from a range of disciplines relevant to global eye health from all regions globally to participate in a three-round, online, Delphi-like, prioritisation process to nominate and rank challenges in global eye health. Through this process, we developed both global and regional priority lists. Findings: Between Sept 1 and Dec 12, 2019, 470 individuals complete round 1 of the process, of whom 336 completed all three rounds (round 2 between Feb 26 and March 18, 2020, and round 3 between April 2 and April 25, 2020) 156 (46%) of 336 were women, 180 (54%) were men. The proportion of participants who worked in each region ranged from 104 (31%) in sub-Saharan Africa to 21 (6%) in central Europe, eastern Europe, and in central Asia. Of 85 unique challenges identified after round 1, 16 challenges were prioritised at the global level; six focused on detection and treatment of conditions (cataract, refractive error, glaucoma, diabetic retinopathy, services for children and screening for early detection), two focused on addressing shortages in human resource capacity, five on other health service and policy factors (including strengthening policies, integration, health information systems, and budget allocation), and three on improving access to care and promoting equity. Interpretation: This list of Grand Challenges serves as a starting point for immediate action by funders to guide investment in research and innovation in eye health. It challenges researchers, clinicians, and policy makers to build collaborations to address specific challenges. Funding: The Queen Elizabeth Diamond Jubilee Trust, Moorfields Eye Charity, National Institute for Health Research Moorfields Biomedical Research Centre, Wellcome Trust, Sightsavers, The Fred Hollows Foundation, The Seva Foundation, British Council for the Prevention of Blindness, and Christian Blind Mission. Translations: For the French, Spanish, Chinese, Portuguese, Arabic and Persian translations of the abstract see Supplementary Materials section.

Recent advances in regenerative therapy have placed the treatment of previously incurable eye diseases within arms’ reach. Achromatopsia is a severe monogenic heritable retinal disease that disrupts cone function from birth, leaving patients with complete colour blindness, low acuity, photosensitivity and nystagmus. While successful gene-replacement therapy in non-primate models of achromatopsia has raised widespread hopes for clinical treatment, it was yet to be determined if and how these therapies can induce new cone function in the human brain. Using a novel multimodal approach, we demonstrate for the first time that gene therapy can successfully activate dormant cone-mediated pathways in children with achromatopsia (CNGA3- and CNGB3-associated, 10–15 years). To test this, we combined functional MRI population receptive field mapping and psychophysics with stimuli that selectively measure cone photoreceptor signalling. We measured cortical and visual cone function before and after gene therapy in four paediatric patients, evaluating treatment-related change against benchmark data from untreated patients (n = 9) and normal-sighted participants (n = 28). After treatment, two of the four children displayed strong evidence for novel cone-mediated signals in visual cortex, with a retinotopic pattern that was not present in untreated achromatopsia and which is highly unlikely to emerge by chance. Importantly, this change was paired with a significant improvement in psychophysical measures of cone-mediated visual function. These improvements were specific to the treated eye, and provide strong evidence for successful read-out and use of new cone-mediated information. These data show for the first time that gene replacement therapy in achromatopsia within the plastic period of development can awaken dormant cone-signalling pathways after years of deprivation. This reveals unprecedented neural plasticity in the developing human nervous system and offers great promise for emerging regenerative therapies.

This study compares visual acuity testing at home with visual acuity testing in a clinical setting.

PURPOSE: To describe, refine, evaluate, and provide normative control data for two freely available tablet-based tests of real-world visual function, using a cohort of young, normally-sighted adults. \ud \ud METHODS: Fifty young (18-40 years), normally-sighted adults completed tablet-based assessments of (1) face discrimination and (2) visual search. Each test was performed twice, to assess test-retest repeatability. Post-hoc analyses were performed to determine the number of trials required to obtain stable estimates of performance. Distributions were fitted to the normative data to determine the 99% population-boundary for normally sighted observers. Participants were also asked to rate their comprehension of each test. \ud \ud RESULTS: Both tests provided stable estimates in around 20 trials (~1-4 min), with only a further reduction of 14%-17% in the 95% Coefficient of Repeatability (CoR95 ) when an additional 40 trials were included. When using only ~20 trials: median durations for the first run of each test were 191 s (Faces) and 51 s (Search); test-retest CoR95 were 0.27 d (Faces) and 0.84 s (Search); and normative 99% population-limits were 3.50 d (Faces) and 3.1 s (Search). No participants exhibited any difficulties completing either test (100% completion rate), and ratings of task-understanding were high (Faces: 9.6 out of 10; Search: 9.7 out of 10). \ud \ud CONCLUSIONS: This preliminary assessment indicated that both tablet-based tests are able to provide simple, quick, and easy-to-administer measures of real-world visual function in normally-sighted young adults. Further work is required to assess their accuracy and utility in older people and individuals with visual impairment. Potential applications are discussed, including their use in clinic waiting rooms, and as an objective complement to Patient Reported Outcome Measures (PROMs).

This study evaluated the feasibility of using a ‘self-calibrating’ display (EIZO CG277) to perform screen-based threshold perimetry. Such displays incorporate their own integrated photometer, so could potentially be used ‘straight out of the box’, without the need for time-consuming and costly luminance calibration by skilled experts. Concerns remain, however, due to the fact that the internal calibration of such devices is imperfect, and lingering doubts regarding the accuracy of screen-based perimetry in general. To evaluate such a system, automated static threshold perimetry was performed in thirty-two normal-sighted adults. In one condition, participants performed a novel screen-based perimetry test, for which the screen was calibrated extensively using traditional photometric techniques/equipment. In a second condition, the same test was performed, but the display was calibrated using only the screen’s integrated photometer (and assuming uniformity across the display). For reference, participants also completed a traditional visual-field assessment using a Humphrey Field Analyzer (HFA). All three tests were performed twice to assess test-retest repeatability (six tests total). The results showed no differences when comparing screen-based perimetric measurements made with internal self-calibration vs full manual calibration (either in terms of mean sensitivity, pointwise sensitivity, test-retest repeatability, or test duration). Furthermore, the accuracy and precision of both were indistinguishable from the current gold standard (HFA), although the HFA was approximately two minutes (~30%) faster. These results indicate that self-calibrating commercial monitors can be used to perform screen-based perimetry almost as well as current clinical devices, and without the need for any specialized knowledge or equipment to setup or maintain. This could facilitate perimetric testing in currently hard-to-reach settings, such as community centers, stroke wards, homes, rural locations, or developing countries.

ObjectivesTo explore the acceptability of home visual field (VF) testing using Eyecatcher among people with glaucoma participating in a 6-month home monitoring pilot study.DesignQualitative study using face-to-face semistructured interviews. Transcripts were analysed using thematic analysis.SettingParticipants were recruited in the UK through an advertisement in the International Glaucoma Association (now Glaucoma UK) newsletter.ParticipantsTwenty adults (10 women; median age: 71 years) with a diagnosis of glaucoma were recruited (including open angle and normal tension glaucoma; mean deviation=2.5 to −29.9 dB).ResultsAll participants could successfully perform VF testing at home. Interview data were coded into four overarching themes regarding experiences of undertaking VF home monitoring and attitudes towards its wider implementation in healthcare: (1) comparisons between Eyecatcher and Humphrey Field Analyser (HFA); (2) capability using Eyecatcher; (3) practicalities for effective wider scale implementation; (4) motivations for home monitoring.ConclusionsParticipants identified a broad range of benefits to VF home monitoring and discussed areas for service improvement. Eyecatcher was compared positively with conventional VF testing using HFA. Home monitoring may be acceptable to at least a subset of people with glaucoma.

PurposeTo describe and demonstrate a more efficient (Maximum Likelihood) method for quantifying visual field progression.DesignMonte Carlo simulation.MethodsTrial-by-trial response data were simulated using a stochastic psychometric model (a “simulated observer”). Simulated Differential Light Sensitivity (DLS) decreased between tests to mimic long-term visual field progression. Progression slopes were fitted, either by fitting a regression slope to independent DLS estimates from each test (conventional method), or by fitting all the raw data combined in a single model (proposed maximum likelihood method).ResultsThe proposed ML method seldom performed worse than a conventional, regression-based approach, and often performed better. For an idealized observer with a lapse (false negative) rate of 0 and a guess (false positive) rate of 0, both methods were equally precise. However, as lapse rate increased, the ML method exhibited less random measurement error. For small numbers of trials this increase in precision translated to a negative progression slope being detected with 95% confidence at least one year/assessment sooner. The only time the ML method was observed to perform worse was when very few trials (N = 4) were combined with very high lapse rates (λ = 0.3): an unlikely but not inconceivable scenario.ConclusionsCombining raw, trial-by-trial response data in a single ML model can provide a more robust estimate of visual field progression than conventional methods (e.g., linear regression), at no additional cost to the patient or clinician (i.e., no additional trials).

BackgroundHealth-care systems across the globe are facing increased pressures to balance the efficient use of resources and at the same time provide high-quality care. There is greater requirement for services to be evidence based, but practices that are of limited clinical effectiveness or cost-effectiveness still occur.ObjectivesOur objectives included completing a concept analysis of de-implementation, surfacing decision-making processes associated with de-implementing through stakeholder engagement, and generating an evidence-based realist programme theory of ‘what works’ in de-implementation.DesignA realist synthesis was conducted using an iterative stakeholder-driven four-stage approach. Phase 1 involved scoping the literature and conducting stakeholder interviews to develop the concept analysis and an initial programme theory. In Phase 2, systematic searches of the evidence were conducted to test and develop this theory, expressed in the form of contingent relationships. These are expressed as context–mechanism–outcomes to show how particular contexts or conditions trigger mechanisms to generate outcomes. Phase 3 consisted of validation and refinement of programme theories through stakeholder interviews. The final phase (i.e. Phase 4) formulated actionable recommendations for service leaders.ParticipantsIn total, 31 stakeholders (i.e. user/patient representatives, clinical managers, commissioners) took part in focus groups and telephone interviews.Data sourcesUsing keywords identified during the scoping work and concept analysis, searches of bibliographic databases were conducted in May 2018. The databases searched were the Cochrane Library, Campbell Collaboration, MEDLINE (via EBSCOhost), the Cumulative Index to Nursing and Allied Health Literature (via EBSCOhost), the National Institute for Health Research Journals Library and the following databases via the ProQuest platform: Applied Social Sciences Index and Abstracts, Social Services Abstracts, International Bibliography of the Social Sciences, Social Sciences Database and Sociological Abstracts. Alerts were set up for the MEDLINE database from May 2018 to December 2018. Online sources were searched for grey literature and snowballing techniques were used to identify clusters of evidence.ResultsThe concept analysis showed that de-implementation is associated with five main components in context and over time: (1) what is being de-implemented, (2) the issues driving de-implementation, (3) the action characterising de-implementation, (4) the extent that de-implementation is planned or opportunistic and (5) the consequences of de-implementation. Forty-two papers were synthesised to identify six context–mechanism–outcome configurations, which focused on issues ranging from individual behaviours to organisational procedures. Current systems can perpetuate habitual decision-making practices that include low-value treatments. Electronic health records can be designed to hide or remove low-value treatments from choice options, foregrounding best evidence. Professionals can be made aware of their decision-making strategies through increasing their attention to low-value practice behaviours. Uncertainty about diagnosis or patients’ expectations for certain treatments provide opportunities for ‘watchful waiting’ as an active strategy to reduce inappropriate investigations and prescribing. The emotional component of clinician–patient relationships can limit opportunities for de-implementation, requiring professional support through multimodal educational interventions. Sufficient alignment between policy, public and professional perspectives is required for de-implementation success.LimitationsSome specific clinical issues (e.g. de-prescribing) dominate the de-implementation evidence base, which may limit the transferability of the synthesis findings. Any realist inquiry generates findings that are essentially cumulative and should be developed through further investigation that extends the range of sources into, for example, clinical research and further empirical studies.ConclusionsThis review contributes to our understanding of how de-implementation of low-value procedures and services can be improved within health-care services, through interventions that make professional decision-making more accountable and the prominence of a whole-system approach to de-implementation. Given the whole-system context of de-implementation, a range of different dissemination strategies will be required to engage with different stakeholders, in different ways, to change practice and policy in a timely manner.Study registrationThis study is registered as PROSPERO CRD42017081030.FundingThis project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full inHealth Services and Delivery Research; Vol. 9, No. 2. See the NIHR Journals Library website for further project information.

Recent advances in regenerative therapy have placed the treatment of many previously incurable eye diseases within arms-reach (Ciulla et al., 2020). Achromatopsia (ACHM) is a severe monogenic heritable retinal disease that disrupts cone function from gestation, leaving patients with complete colour blindness, low acuity, photosensitivity, and nystagmus (Hirji, Aboshiha, et al., 2018). In non-primate animal models of ACHM, retinal gene-replacement therapy has successfully induced cone function in the young (Alexander et al., 2007; Carvalho et al., 2011), but it was yet to be determined if and when these therapies could effectively impact cone-mediated pathways in the human brain. Here we demonstrate in children with ACHM that gene therapy can yield substantial improvement in cone-mediated vision, via cascading effects on signal transmission from retina to cortex. To measure the effects of treatment in children with ACHM (CNGA3- and CNGB3-associated, all aged 10+ years), we developed novel visual stimuli, calibrated to selectively activate cone photoreceptors. We used these in behavioural psychophysics and functional MRI with population receptive field mapping, pre- and post-treatment. The results of treatment, contextualized against data from 12 untreated ACHM patients and 25 normal-sighted, revealed that six months post-therapy, two patients displayed novel responses to our cone-selective stimuli in the visual cortex, with a retinotopic organisation characteristic of normal-sighted individuals, not present in untreated ACHM. This was paired with significant improvement in cone-mediated perception specific to the treated eye, and self-reports of improved vision. Two other patients did not show a post-treatment effect, potentially reflecting individual differences in therapeutic outcome. Together, these data show that gene replacement therapy in humans with ACHM can activate dormant cone pathways despite long-term deprivation. This offers great promise for regenerative therapies, and their ability to trigger the neural plasticity needed to cure congenital vision loss in human patients.

Background Glaucoma services are under unprecedented strain. The UK Healthcare Safety Investigation Branch recently called for new ways to identify glaucoma patients most at risk of developing sight loss, and of filtering-out false-positive referrals. Here, we evaluate the feasibility of one such technology, Eyecatcher: a free, tablet-based ‘triage’ perimeter, designed to be used unsupervised in clinic waiting areas. Eyecatcher does not require a button or headrest: patients are simply required to look at fixed-luminance dots as they appear. Methods Seventy-seven people were tested twice using Eyecatcher (one eye only) while waiting for a routine appointment in a UK glaucoma clinic. The sample included individuals with an established diagnosis of glaucoma, and false-positive new referrals (no visual field or optic nerve abnormalities). No attempts were made to control the testing environment. Patients wore their own glasses and received minimal task instruction. Results Eyecatcher was fast (median: 2.5 min), produced results in good agreement with standard automated perimetry (SAP), and was rated as more enjoyable, less tiring and easier to perform than SAP (all p −2 dB). And it was able to flag two thirds of false-positive referrals as functionally normal. However, eight people (10%) failed to complete the test twice, and reasons for this limitation are discussed. Conclusions Tablet-based eye-movement perimetry could potentially provide a pragmatic way of triaging busy glaucoma clinics (ie, flagging high-risk patients and possible false-positive referrals).

Purpose: To describe, validate, and provide preliminary normative data for an open-source eye-movement perimeter (Eyecatcher).\ud \ud Methods: Visual field testing was performed monocularly in 64 normally sighted young adults, using (i) a Humphrey Field Analyzer (HFA) and (ii) the novel Eyecatcher procedure. Eyecatcher used a remote eye-tracker to position stimuli relative to the current point of fixation, and observers responded by looking towards the stimulus. In both tests, Goldman III stimuli were sampled from a 24-2 grid, and were presented against a 10 cd/m2 background. Participants completed each test twice to assess test–retest repeatability.\ud \ud Results: Mean Sensitivity (MS) did not differ between Eyecatcher and the HFA (P = 0.086), and both tests exhibited similar test–retest repeatability (CoREyecatcher = ±1.86 dB; CoRHFA = ±1.95 dB). Eyecatcher was also able to detect changes in sensitivity across the normal visual field (the “Hill of Vision”), and could differentiate the physiological blind spot from adjacent retinal locations. Mean sensitivities and 95% limits of agreement are described for each pointwise location.\ud \ud Conclusions: Eyecatcher can use eye movements to assess visual fields in young, normally sighted adults. In such observers, it provides results similar to the current gold standard clinical device (HFA).\ud \ud Translational Relevance: Given further development, eye movement perimeters such as Eyecatcher could be particularly useful for individuals unable to perform traditional perimetric assessments, such as young children or stroke patients. Full technical details and information on how to freely acquire the source code are included.

Purpose: To explore the feasibility of using various easy-to-obtain biomarkers to monitor non-compliance (measurement error) during visual field assessments.Methods: Forty-two healthy adults (42 eyes) and seven glaucoma patients (14 eyes) underwent two same-day visual field assessments. An ordinary webcam was used to compute seven potential biomarkers of task compliance, based primarily on eye gaze, head pose, and facial expression. We quantified the association between each biomarker and measurement error, as defined by (1) test-retest differences in overall test scores (mean sensitivity), and (2) failures to respond to visible stimuli on individual trials (stimuli -3 dB or more brighter than threshold).Results: In healthy eyes, three of the seven biomarkers were significantly associated with overall (test-retest) measurement error (P = 0.003-0.007), and at least two others exhibited possible trends (P = 0.052-0.060). The weighted linear sum of all seven biomarkers was associated with overall measurement error, in both healthy eyes (r = 0.51, P Conclusions: Inexpensive, autonomous measures of task compliance are associated with measurement error in visual field assessments, in terms of both the overall reliability of a test and failures to respond on particular trials ("lapses"). This could be helpful for identifying low-quality assessments and for improving assessment techniques (e.g., by discounting suspect responses or by automatically triggering comfort breaks or encouragement).Translational Relevance: This study explores a potential way of improving the reliability of visual field assessments, a crucial but notoriously unreliable clinical measure.

Purpose To assess accuracy and adherence of visual field (VF) home-monitoring in a pilot sample of glaucoma patients. Design Prospective longitudinal feasibility and reliability study. Methods Twenty adults (median 71 years) with an established diagnosis of glaucoma were issued a tablet-perimeter (Eyecatcher), and were asked to perform one VF home-assessment per eye, per month, for 6 months (12 tests total). Before and after home-monitoring, two VF assessments were performed in-clinic using Standard Automated Perimetry (SAP; 4 tests total, per eye). Results All 20 participants could perform monthly home-monitoring, though one participant stopped after 4 months (Adherence: 98%). There was good concordance between VFs measured at home and in the clinic (r = 0.94, P < 0.001). In 21 of 236 tests (9%) Mean Deviation deviated by more than ±3 dB from the median. Many of these anomalous tests could be identified by applying machine learning techniques to recordings from the tablets’ front-facing camera (Area Under the ROC Curve = 0.78). Adding home-monitoring data to 2 SAP tests made 6 months apart reduced measurement error (between-test measurement variability) in 97% of eyes, with mean absolute error more than halving in 90% of eyes. Median test duration was 4.5 mins (Quartiles: 3.9 – 5.2 mins). Substantial variations in ambient illumination had no observable effect on VF measurements (r = 0.07, P = 0.320). Conclusions Home-monitoring of VFs is viable for some patients, and may provide clinically useful data., Highlights • Twenty glaucoma patients performed visual field assessments at home for 6 months • The data were in good agreement with conventional measurements made in clinic • Home monitoring may be viable and useful for some patients • Practical concerns and future directions for home monitoring are also discussed

Simulations of visual impairment are used to educate and inform the public. However, evidence regarding their accuracy remains lacking. Here we evaluated the effectiveness of modern digital technologies to simulate the everyday difficulties caused by glaucoma. 23 normally sighted adults performed two everyday tasks that glaucoma patients often report difficulties with: a visual search task in which participants attempted to locate a mobile phone in virtual domestic environments (virtual reality (VR)), and a visual mobility task in which participants navigated a physical, room-scale environment, while impairments were overlaid using augmented reality (AR). On some trials, a gaze-contingent simulated scotoma—generated using perimetric data from a real patient with advanced glaucoma—was presented in either the superior or inferior hemifield. The main outcome measure was task completion time. Eye and head movements were also tracked and used to assess individual differences in looking behaviors. The results showed that the simulated impairments substantially impaired performance in both the VR (visual search) and AR (visual mobility) tasks (both P P P P

Macular degeneration is the leading cause of blindness in the developed world. Whilst most patients lose sight owing to atrophic changes, no treatments currently exist that improve the vision deficit due to atrophy. Here, we identify loss of lateral inhibition as a specific mechanism by which photoreceptor degeneration reduces visual function beyond the atrophic area. We find that this inhibition is adaptive, and that if modulated can improve visual function, making inhibitory circuits an unexpected therapeutic target for age related macular degeneration and related disorders.

Purpose: To compare severity of visual field (VF) loss at first presentation in glaucoma clinics in England and Tanzania. Methods: Large archives of VF records from automated perimetry were used to retrospectively examine vision loss at first presentation in glaucoma clinics in Tanzania (N = 1,502) and England (N = 9,264). Mean deviation (MD) of the worse eye at the first hospital visit was used as an estimate of detectable VF loss severity. Results: In Tanzania, 44.7% {CI95%: 42.2, 47.2} of patients presented with severe VF loss (< −20 dB), versus 4.6% {4.1, 5.0} in England. If we consider late presentation to also include cases of advanced loss (-12.01 dB to -20 dB), then the proportion of patients presenting late was 58.1% {55.6, 60.6} and 14.0% {13.3, 14.7}, respectively. The proportion of late presentations was greater in Tanzania at all ages, but the difference was particularly pronounced among working-age adults, with 50.3% {46.9, 53.7} of 18–65-year-olds presenting with advanced or severe VF loss, versus 10.2% {9.3, 11.3} in England. In both countries, men were more likely to present late than women. Conclusions: Late presentation of glaucoma is a problem in England, and an even greater challenge in Tanzania. Possible solutions are discussed, including increased community eye-care, and a more proactive approach to case finding through the use of disruptive new technologies, such as low-cost, portable diagnostic aids.

Achromatopsia (ACHM) is an inherited retinal disease characterised by complete loss of cone photoreceptor function from birth. In recent years, gene therapies have successfully been used to induce signal processing in dormant cones in animal models of ACHM, with greater functional benefits for younger animals. With several completed or on-going clinical trials of gene therapy for ACHM, preliminary evidence suggests that effects on visual function in adults with ACHM may be subtle. Given the known constraints of age on neural plasticity, it is possible that gene therapy earlier in life will have a greater impact. Sensitive, child-friendly tests of cone function are therefore needed to facilitate the optimisation of these treatment strategies. Here, we present a new method that leverages a multimodal approach, linking psychophysical estimates of cone function to cone-mediated signals in visual cortex, measured using fMRI. In a case study of two children with ACHM undergoing gene therapy, we find individual differences in recovery of cone function over time, with one child demonstrating strong concurrent evidence of improved cone function, and retinotopically organised responses in visual cortex to cone-selective stimuli. Integrated fMRI and psychophysical measures may provide insight into the utility of new sight-rescuing therapies at different stages of human development.

IMPORTANCE: Sight is often considered to be the sense most valued by the general public, but there are limited empirical data to support this. This study provides empirical evidence for frequent assertions made by practitioners, researchers, and funding agencies that sight is the most valued sense. OBJECTIVE: To determine which senses are rated most valuable by the general public and quantify attitudes toward sight and hearing loss in particular. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional web-based survey was conducted from March to April 2016 through a market research platform and captured a heterogeneous sample of 250 UK adults ages 22 to 80 years recruited in March 2016. The data were analyzed from October to December 2018. MAIN OUTCOMES AND MEASURES: Participants were first asked to rank the 5 traditional senses (sight, hearing, touch, smell, and taste) plus 3 other senses (balance, temperature, and pain) in order of most valuable (8) to least valuable (1). Next, the fear of losing sight and hearing was investigated using a time tradeoff exercise. Participants chose between 10 years without sight/hearing vs varying amounts of perfect health (from 0-10 years). RESULTS: Of 250 participants, 141 (56.4%) were women and the mean (SD) age was 49.5 (14.6) years. Two hundred twenty participants (88%) ranked sight as their most valuable sense (mean [SD] rating, 7.8 [0.9]; 95% CI, 7.6-7.9). Hearing was ranked second (mean [SD] rating, 6.2 [1.3]; 95% CI 6.1-6.4) and balance third (mean [SD] rating, 4.9 [1.7]; 95% CI, 4.7-5.1). All 3 were ranked above the traditional senses of touch, taste, and smell (F(7 )= 928.4; P

It is often unclear which course of action gives the best outcome. We can reduce this uncertainty by gathering more information, but gathering information always comes at a cost. For example, a sports player waiting too long to judge a ball's trajectory will run out of time to intercept it. Efficient samplers must therefore optimize a trade-off: when the costs of collecting further information exceed the expected benefits, they should stop sampling and start acting. In visually guided tasks, adults can make these trade-offs efficiently, correctly balancing any reductions in visuomotor uncertainty against cost factors associated with increased sampling. To investigate how this ability develops during childhood, we tested 6- to 11-year-olds, adolescents, and adults on a visual localization task in which the costs and benefits of sampling were formalized in a quantitative framework. This allowed us to compare participants to each other and to an ideal observer who maximizes expected reward. Visual sampling became substantially more efficient between 6 and 11 years, converging onto adult performance in adolescence. Younger children systematically undersampled information relative to the ideal observer and varied their sampling strategy more. Further analyses suggested that young children used a suboptimal decision rule that insufficiently accounted for the chance of task failure, in line with a late developing ability to compute with probabilities and costs. We therefore propose that late development of efficient information sampling, a crucial element of real-world decision-making under risk, may form an important component of suboptimality in child perception, action, and decision-making. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Maximum Likelihood (ML) estimators such as QUEST+ allow complex psychophysical measurements to be made more quickly and precisely than traditional staircase techniques. They could therefore be useful for quantifying sensory function in populations with limited attention spans, such as children. To test this, the present study empirically evaluated the performance of an ML estimator (QUEST+) versus a traditional Up-Down Weighted Staircase in children and adults. Seventy-one children (4.7–14.7 years) and 43 adults (18.1–29.6 years) completed a typical psychophysical procedure: Contrast Sensitivity Function (CSF) determination. Some participants were tested twice with the same method (QUEST+ or Staircase), allowing test-retest repeatability to be quantified. Others were tested once each with either method (QUEST+ and Staircase), allowing accuracy to be quantified. The results showed that QUEST+ was more efficient: In both children and adults, approximately half the number of ML trials were required to attain comparable levels of accuracy and reliability as a traditional Staircase paradigm, and plausible CSF estimates could be made in even the youngest children. The ML procedure was also as robust as the Staircase to lapses in concentration, and its performance did not depend on prespecifying correct model priors. The results show that ML estimators could greatly improve our ability to study sensory processes and detect impairments in children, although important practical considerations for-and-against their use are discussed.

Purpose: Visual field (VF) examination by standard automated perimetry (SAP) is an important method of clinical assessment. However, the complexity of the test, and its use of bulky, expensive equipment makes it impractical for case-finding. We propose and evaluate a new approach to paracentral VF assessment that combines an inexpensive eye-tracker with a portable tablet computer (“Eyecatcher”).\ud \ud Methods: Twenty-four eyes from 12 glaucoma patients, and 12 eyes from six age-similar controls were examined. Participants were tested monocularly (once per eye), with both the novel Eyecatcher test and traditional SAP (HFA SITA standard 24-2). For Eyecatcher, the participant's task was to simply to look at a sequence of fixed-luminance dots, presented relative to the current point of fixation. Start and end fixations were used to determine locations where stimuli were seen/unseen, and to build a continuous map of sensitivity loss across a VF of approximately 20°.\ud \ud Results: Eyecatcher was able to clearly separate patients from controls, and the results were consistent with those from traditional SAP. In particular, mean Eyecatcher scores were strongly correlated with mean deviation scores (r2 = 0.64, P < 0.001), and there was good concordance between corresponding VF locations (∼84%). Participants reported that Eyecatcher was more enjoyable, easier to perform, and less tiring than SAP (all P < 0.001).\ud \ud Conclusions: Portable perimetry using an inexpensive eye-tracker and a tablet computer is feasible, although possible means of improvement are suggested.\ud \ud Translational Relevance: Such a test could have significant utility as a case finding device.

Although the contrast sensitivity function (CSF) changes markedly during infancy, there is no consensus regarding whether, how, and why it continues to develop in later childhood. Here, we analyzed previously published data (N = 1928 CSFs), and present new psychophysical findings from 98 children (4.7–14.8 years) and 50 adults (18.1–29.7 years), in order to answer the following questions: (1) Does the CSF change during childhood? (2) How large is the developmental effect size? (3) Are any changes uniform across the CSF, or frequency-specific? and (4) Can some or all of the changes be explained by “non-visual” (i.e. procedural/cognitive) factors, such as boredom or inattentiveness? The new data were collected using a four-alternative forced-choice (4AFC) Gabor-detection task, with two different psychophysical procedures (Weighted Staircase; QUEST+), and suprathreshold (false-negative) catch trials to quantify lapse rates. It is shown that from ages 4 to 18 years, the CSF improves (at an exponentially decaying rate) by approximately 0.3 log10 units (a doubling of contrast sensitivity [CS]), with 90% of this change complete by 12 years of age. The size of the effect was small relative to individual variability, with age alone explaining less than one sixth of variability (16%), and most children performing as well as some adults (i.e. falling within the 90% population limits for adults). Development was frequency-specific, with changes occurring primarily around or below the CSF peak (≤ 4 cpd). At least half — and potentially all — of the changes observed could be explained by non-visual factors (e.g. lapses in concentration), although possible biological mechanisms are discussed.

Purpose To describe and evaluate a free, online tool for automatically segmenting optical coherence tomography (OCT) images from different devices and computing summary measures such as retinal thickness. Methods ReLayer (https://relayer.online) is an online platform to which OCT scan images can be uploaded and analyzed. Results can be downloaded as plaintext (.csv) files. The segmentation method includes a novel, one-dimensional active contour model, designed to locate the inner limiting membrane, inner/outer segment, and retinal pigment epithelium. The method, designed for B-scans from Heidelberg Engineering Spectralis, was adapted for Topcon 3D OCT-2000 and OptoVue AngioVue. The method was applied to scans from healthy and pathological eyes, and was validated against segmentation by the manufacturers, the IOWA Reference Algorithms, and manual segmentation. Results Segmentation of a B-scan took ≤1 second. In healthy eyes, mean difference in retinal thickness from ReLayer and the reference standard was below the resolution of the Spectralis and 3D OCT-2000, and slightly above the resolution of the AngioVue. In pathological eyes, ReLayer performed similarly to IOWA (P = 0.97) and better than Spectralis (P < 0.001). Conclusions A free online platform (ReLayer) is capable of segmenting OCT scans with similar speed, accuracy, and reliability as the other tested algorithms, but offers greater accessibility. ReLayer could represent a valuable tool for researchers requiring the full segmentation, often not made available by commercial software. Translational Relevance A free online platform (ReLayer) provides free, accessible segmentation of OCT images: data often not available via existing commercial software.

Eye movements of glaucoma patients have been shown to differ from age-similar control groups when performing everyday tasks, such as reading (Burton et al., 2012; Smith et al., 2014) [1,2], visual search (Smith et al., 2012) [3], face recognition (Glen et al., 2013) [4], driving, and viewing static images (Smith et al., 2012) [5]. Described here is the dataset from a recent publication in which we compared the eye-movements of 44 glaucoma patients and 32 age-similar controls, while they watched a series of short video clips taken from television programs (Crabb et al., 2018) [6]. Gaze was recorded at 1000 Hz using a remote eye-tracker. We also provide demographic information and results from a clinical examination of vision for each participant. Keywords: Eye movements, Scanpaths, Visual fields, Glaucoma, Eye tracking

When assessing the perceptual abilities of children, researchers tend to use psychophysical techniques designed for use with adults. However, children’s poorer attentiveness might bias the threshold estimates obtained by these methods. Here, we obtained speed discrimination threshold estimates in 6- to 7-year-old children in UK Key Stage 1 (KS1), 7- to 9-year-old children in Key Stage 2 (KS2), and adults using three psychophysical procedures: QUEST, a 1-up 2-down Levitt staircase, and Method of Constant Stimuli (MCS). We estimated inattentiveness using responses to “easy” catch trials. As expected, children had higher threshold estimates and made more errors on catch trials than adults. Lower threshold estimates were obtained from psychometric functions fit to the data in the QUEST condition than the MCS and Levitt staircases, and the threshold estimates obtained when fitting a psychometric function to the QUEST data were also lower than when using the QUEST mode. This suggests that threshold estimates cannot be compared directly across methods. Differences between the procedures did not vary significantly with age group. Simulations indicated that inattentiveness biased threshold estimates particularly when threshold estimates were computed as the QUEST mode or the average of staircase reversals. In contrast, thresholds estimated by post-hoc psychometric function fitting were less biased by attentional lapses. Our results suggest that some psychophysical methods are more robust to attentiveness, which has important implications for assessing the perception of children and clinical groups.

The effects of eye disease cannot be depicted accurately using traditional media. Consequently, public understanding of eye disease is often poor. We present a VR/AR system for simulating common visual impairments, including disability glare, spatial distortions (Metamorphopsia), the selective blurring and filling-in of information across the visual field, and color vision deficits. Unlike most existing simulators, the simulations are informed by patients' self-reported symptoms, can be quantitatively manipulated to provide custom disease profiles, and support gaze-contingent presentation (i.e., when using a VR/AR headset that contains eye-tracking technology, such as the Fove0). Such a simulator could be used as a teaching/empathy aid, or as a tool for evaluating the accessibility of new products and environments.

Sensory judgments improve with practice. Such perceptual learning is often thought to reflect an increase in perceptual sensitivity. However, it may also represent a decrease in response bias, with unpracticed observers acting in part on a priori hunches rather than sensory evidence. To examine whether this is the case, 55 observers practiced making a basic auditory judgment (yes/no amplitude-modulation detection or forced-choice frequency/amplitude discrimination) over multiple days. With all tasks, bias was present initially, but decreased with practice. Notably, this was the case even on supposedly "bias-free," 2-alternative forced-choice, tasks. In those tasks, observers did not favor the same response throughout (stationary bias), but did favor whichever response had been correct on previous trials (nonstationary bias). Means of correcting for bias are described. When applied, these showed that at least 13% of perceptual learning on a forced-choice task was due to reduction in bias. In other situations, changes in bias were shown to obscure the true extent of learning, with changes in estimated sensitivity increasing once bias was corrected for. The possible causes of bias and the implications for our understanding of perceptual learning are discussed.

Human adults can combine perceptual estimates from different senses to minimize uncertainty, by taking a reliability-weighted average (the maximum likelihood estimate, MLE). Although research has shown that healthy human adults reweight estimates as their reliability changes from one trial to the next, less is known about how humans adapt to gradual long-term changes in sensory reliability. This study assessed whether individuals diagnosed with progressive visual deterioration, due to retinal disease, combined auditory and visual cues to location according to optimal (MLE) predictions. Twelve patients with central visual loss, 10 patients with peripheral visual loss, and 12 normally sighted adults were asked to localize visual and/or auditory targets in central (1°-18°) and peripheral (36°-53°) locations. Normally sighted adults and patients with peripheral visual loss showed multisensory uncertainty reduction and cue weighting in line with MLE predictions. In contrast, patients with central visual loss did not weight estimates appropriately in either the center or the periphery, and failed to meet MLE predictions in the periphery. Our results show that one visual loss patient group succeeded at optimal cue combination, whereas the other patient group (patients with central vision loss) did not. We propose that sensory remapping due to changes in fixation behavior may contribute to apparent failures in the latter group. (PsycINFO Database Record

Purpose.: To validate a novel, automated test of infant resolution acuity based on remote eye-tracking.\ud \ud Methods.: Infants aged 2 to 12 months were tested binocularly using a new adaptive computerized test of infant vision using eye tracking (ACTIVE), and Keeler infant acuity cards (KIAC). The ACTIVE test ran automatically, using remote eye-tracking to assess whether the infant fixated a black-and-white grating of variable spatial frequency. Test-retest reliability was assessed by performing each test twice. Accuracy was assessed by comparing acuity measures across tests and with established age-norms, and by comparing low-contrast acuity estimates in adults with data reported previously.\ud \ud Results.: All infants completed the ACTIVE test at least once. Median test duration was 101 seconds. Measured visual acuity increased with age (P < 0.001), and 90% of mean acuity estimates were within previously published 90% tolerance limits (based on acuity-card age norms). Acuity estimates were also correlated, within-subjects, with results from the KIAC (P = 0.004). In terms of reliability, 86% of acuity estimates deviated by ≤1 octave, with no significant difference in test-retest reliability between the ACTIVE and KIAC procedures (P = 0.461). In adults, acuity estimates from the ACTIVE test did not differ significantly from values reported by previous authors (P > 0.183).\ud \ud Conclusions.: An adaptive computerized test of infant vision using eye-tracking provides a rapid, automated measure of resolution acuity in preverbal infants. The ACTIVE performed comparably to the current clinical gold standard (acuity cards) in terms of testability, reliability, and accuracy, and its principles can be extended to measure other visual functions.

Perceptual learning has traditionally been portrayed as a bottom-up phenomenon that improves encoding or decoding of the trained stimulus. Cognitive skills such as attention and memory are thought to drive, guide and modulate learning but are, with notable exceptions, not generally considered to undergo changes themselves as a result of training with simple perceptual tasks. Moreover, shifts in threshold are interpreted as shifts in perceptual sensitivity, with no consideration for non-sensory factors (such as response bias) that may contribute to these changes. Accumulating evidence from our own research and others shows that perceptual learning is a conglomeration of effects, with training-induced changes ranging from the lowest (noise reduction in the phase locking of auditory signals) to the highest (working memory capacity) level of processing, and includes contributions from non-sensory factors that affect decision making even on a “simple” auditory task such as frequency discrimination. We discuss our emerging view of learning as a process that increases the signal-to-noise ratio associated with perceptual tasks by tackling noise sources and inefficiencies that cause performance bottlenecks, and present some implications for training populations other than young, smart, attentive and highly-motivated college students.

This paper examines what mechanisms underlie auditory perceptual learning. Fifteen normal hearing adults performed two-alternative, forced choice, pure tone frequency discrimination for four sessions. External variability was introduced by adding a zero-mean Gaussian random variable to the frequency of each tone. Measures of internal noise, encoding efficiency, bias, and inattentiveness were derived using four methods (model fit, classification boundary, psychometric function, and double-pass consistency). The four methods gave convergent estimates of internal noise, which was found to decrease from 4.52 to 2.93 Hz with practice. No group-mean changes in encoding efficiency, bias, or inattentiveness were observed. It is concluded that learned improvements in frequency discrimination primarily reflect a reduction in internal noise. Data from highly experienced listeners and neural networks performing the same task are also reported. These results also indicated that auditory learning represents internal noise reduction, potentially through the re-weighting of frequency-specific channels.

Purpose: To assess the feasibility of macular integrity assessment (MAIA) microperimetry (MP) in children. Also to establish representative outcome measures (differential light sensitivity, fixation stability, test–retest reliability) for children without visual impairment.\ud \ud Methods: Thirty-three adults and 33 children (9–12 years) were asked to perform three monocular MAIA examinations within a single session (dominant eye only).\ud \ud Results: Children exhibited poorer test–retest reliability than adults for measures of both mean sensitivity (95% coefficient of repeatability [CoR95] = 2.7 vs. 2.3 dB, P = 0.036) and pointwise sensitivity (CoR95 = 6.2 vs. 5.7 dB, P < 0.001). Mean sensitivity was lower in children (27.6 vs. 29.5 dB, P < 0.001), and fixation stability was poorer (95% bivariate contour ellipse area [BCEA95] = 4.58 vs. 1.14, P < 0.001). Mean sensitivity was negatively correlated with fixation stability (r = −0.44, P < 0.001). Both children and adults exhibited substantial practice effects, with mean sensitivity improving by 0.5 dB (adults) and 0.9 dB (children) between examinations 1 and 2 (P ≤ 0.017). There were no significant differences between examinations 2 and 3 (P ≥ 0.374).\ud \ud Conclusions: Microperimetry is feasible in 9- to 12-year-old children. However, systematically lower sensitivities mean that the classification boundary for “healthy” performance should be lowered in children, pending development of techniques to improve attentiveness/fixation that may reduce or remove this difference. High measurement variability suggests that the results of multiple tests should be averaged when possible. Learning effects are a potential confound, and it is recommended that the results of the first examination be discarded.

The mature visual system condenses complex scenes into simple summary statistics (e.g., average size, location, orientation, etc.). However, children, often perform poorly on perceptual averaging tasks. Children's difficulties are typically thought to represent the suboptimal implementation of an adult‐like strategy. This paper examines another possibility: that children actually make decisions in a qualitatively different way to adults (optimal implementation of a non‐ideal strategy). Ninety children (6–7, 8–9, 10–11 years) and 30 adults were asked to locate the middle of randomly generated dot‐clouds. Nine plausible decision strategies were formulated, and each was fitted to observers' trial‐by‐trial response data (Reverse Correlation). When the number of visual elements was low (N < 6), children used a qualitatively different decision strategy from adults: appearing to “join up the dots” and locate the gravitational center of the enclosing shape. Given denser displays, both children and adults used an ideal strategy of arithmetically averaging individual points. Accounting for this difference in decision strategy explained 29% of children's lower precision. These findings suggest that children are not simply suboptimal at performing adult‐like computations, but may at times use sensible, but qualitatively different strategies to make perceptual judgments. Learning which strategy is best in which circumstance might be an important driving factor of perceptual development.

Psychophysical studies have frequently found that adults with normal hearing exhibit systematic errors (biases) in their auditory localisation judgments. Here we tested (i) whether systematic localisation errors could reflect reliance on prior knowledge, as has been proposed for other systematic perceptual biases, and (ii) whether auditory localisation biases can be reduced following training with accurate visual feedback. Twenty-four normal hearing participants were asked to localise the position of a noise burst along the azimuth before, during, and after training with visual feedback. Consistent with reliance on prior knowledge to reduce sensory uncertainty, we found that auditory localisation biases increased when auditory localisation uncertainty increased. Specifically, participants mis-localised auditory stimuli as being more eccentric than they were, and did so more when auditory uncertainty was greater. However, biases also increased with eccentricity, despite no corresponding increase in uncertainty, which is not readily explained by use of a simple prior favouring peripheral locations. Localisation biases decreased (improved) following training with visual feedback, but the reliability of the visual feedback stimulus did not change the effects of training. We suggest that further research is needed to identify alternative mechanisms, besides use of prior knowledge, that could account for increased perceptual biases under sensory uncertainty.

To investigate whether glaucoma produces measurable changes in eye movements.Fifteen glaucoma patients with asymmetric vision loss (difference in mean deviation [MD]6 dB between eyes) were asked to monocularly view 120 images of natural scenes, presented sequentially on a computer monitor. Each image was viewed twice-once each with the better and worse eye. Patients' eye movements were recorded with an Eyelink 1000 eye-tracker. Eye-movement parameters were computed and compared within participants (better eye versus worse eye). These parameters included a novel measure: saccadic reversal rate (SRR), as well as more traditional metrics such as saccade amplitude, fixation counts, fixation duration, and spread of fixation locations (bivariate contour ellipse area [BCEA]). In addition, the associations of these parameters with clinical measures of vision were investigated.In the worse eye, saccade amplitude\(\def\upalpha{\unicode[Times]{x3B1}}\)\(\def\upbeta{\unicode[Times]{x3B2}}\)\(\def\upgamma{\unicode[Times]{x3B3}}\)\(\def\updelta{\unicode[Times]{x3B4}}\)\(\def\upvarepsilon{\unicode[Times]{x3B5}}\)\(\def\upzeta{\unicode[Times]{x3B6}}\)\(\def\upeta{\unicode[Times]{x3B7}}\)\(\def\uptheta{\unicode[Times]{x3B8}}\)\(\def\upiota{\unicode[Times]{x3B9}}\)\(\def\upkappa{\unicode[Times]{x3BA}}\)\(\def\uplambda{\unicode[Times]{x3BB}}\)\(\def\upmu{\unicode[Times]{x3BC}}\)\(\def\upnu{\unicode[Times]{x3BD}}\)\(\def\upxi{\unicode[Times]{x3BE}}\)\(\def\upomicron{\unicode[Times]{x3BF}}\)\(\def\uppi{\unicode[Times]{x3C0}}\)\(\def\uprho{\unicode[Times]{x3C1}}\)\(\def\upsigma{\unicode[Times]{x3C3}}\)\(\def\uptau{\unicode[Times]{x3C4}}\)\(\def\upupsilon{\unicode[Times]{x3C5}}\)\(\def\upphi{\unicode[Times]{x3C6}}\)\(\def\upchi{\unicode[Times]{x3C7}}\)\(\def\uppsy{\unicode[Times]{x3C8}}\)\(\def\upomega{\unicode[Times]{x3C9}}\)\(\def\bialpha{\boldsymbol{\alpha}}\)\(\def\bibeta{\boldsymbol{\beta}}\)\(\def\bigamma{\boldsymbol{\gamma}}\)\(\def\bidelta{\boldsymbol{\delta}}\)\(\def\bivarepsilon{\boldsymbol{\varepsilon}}\)\(\def\bizeta{\boldsymbol{\zeta}}\)\(\def\bieta{\boldsymbol{\eta}}\)\(\def\bitheta{\boldsymbol{\theta}}\)\(\def\biiota{\boldsymbol{\iota}}\)\(\def\bikappa{\boldsymbol{\kappa}}\)\(\def\bilambda{\boldsymbol{\lambda}}\)\(\def\bimu{\boldsymbol{\mu}}\)\(\def\binu{\boldsymbol{\nu}}\)\(\def\bixi{\boldsymbol{\xi}}\)\(\def\biomicron{\boldsymbol{\micron}}\)\(\def\bipi{\boldsymbol{\pi}}\)\(\def\birho{\boldsymbol{\rho}}\)\(\def\bisigma{\boldsymbol{\sigma}}\)\(\def\bitau{\boldsymbol{\tau}}\)\(\def\biupsilon{\boldsymbol{\upsilon}}\)\(\def\biphi{\boldsymbol{\phi}}\)\(\def\bichi{\boldsymbol{\chi}}\)\(\def\bipsy{\boldsymbol{\psy}}\)\(\def\biomega{\boldsymbol{\omega}}\)\(\def\bupalpha{\unicode[Times]{x1D6C2}}\)\(\def\bupbeta{\unicode[Times]{x1D6C3}}\)\(\def\bupgamma{\unicode[Times]{x1D6C4}}\)\(\def\bupdelta{\unicode[Times]{x1D6C5}}\)\(\def\bupepsilon{\unicode[Times]{x1D6C6}}\)\(\def\bupvarepsilon{\unicode[Times]{x1D6DC}}\)\(\def\bupzeta{\unicode[Times]{x1D6C7}}\)\(\def\bupeta{\unicode[Times]{x1D6C8}}\)\(\def\buptheta{\unicode[Times]{x1D6C9}}\)\(\def\bupiota{\unicode[Times]{x1D6CA}}\)\(\def\bupkappa{\unicode[Times]{x1D6CB}}\)\(\def\buplambda{\unicode[Times]{x1D6CC}}\)\(\def\bupmu{\unicode[Times]{x1D6CD}}\)\(\def\bupnu{\unicode[Times]{x1D6CE}}\)\(\def\bupxi{\unicode[Times]{x1D6CF}}\)\(\def\bupomicron{\unicode[Times]{x1D6D0}}\)\(\def\buppi{\unicode[Times]{x1D6D1}}\)\(\def\buprho{\unicode[Times]{x1D6D2}}\)\(\def\bupsigma{\unicode[Times]{x1D6D4}}\)\(\def\buptau{\unicode[Times]{x1D6D5}}\)\(\def\bupupsilon{\unicode[Times]{x1D6D6}}\)\(\def\bupphi{\unicode[Times]{x1D6D7}}\)\(\def\bupchi{\unicode[Times]{x1D6D8}}\)\(\def\buppsy{\unicode[Times]{x1D6D9}}\)\(\def\bupomega{\unicode[Times]{x1D6DA}}\)\(\def\bupvartheta{\unicode[Times]{x1D6DD}}\)\(\def\bGamma{\bf{\Gamma}}\)\(\def\bDelta{\bf{\Delta}}\)\(\def\bTheta{\bf{\Theta}}\)\(\def\bLambda{\bf{\Lambda}}\)\(\def\bXi{\bf{\Xi}}\)\(\def\bPi{\bf{\Pi}}\)\(\def\bSigma{\bf{\Sigma}}\)\(\def\bUpsilon{\bf{\Upsilon}}\)\(\def\bPhi{\bf{\Phi}}\)\(\def\bPsi{\bf{\Psi}}\)\(\def\bOmega{\bf{\Omega}}\)\(\def\iGamma{\unicode[Times]{x1D6E4}}\)\(\def\iDelta{\unicode[Times]{x1D6E5}}\)\(\def\iTheta{\unicode[Times]{x1D6E9}}\)\(\def\iLambda{\unicode[Times]{x1D6EC}}\)\(\def\iXi{\unicode[Times]{x1D6EF}}\)\(\def\iPi{\unicode[Times]{x1D6F1}}\)\(\def\iSigma{\unicode[Times]{x1D6F4}}\)\(\def\iUpsilon{\unicode[Times]{x1D6F6}}\)\(\def\iPhi{\unicode[Times]{x1D6F7}}\)\(\def\iPsi{\unicode[Times]{x1D6F9}}\)\(\def\iOmega{\unicode[Times]{x1D6FA}}\)\(\def\biGamma{\unicode[Times]{x1D71E}}\)\(\def\biDelta{\unicode[Times]{x1D71F}}\)\(\def\biTheta{\unicode[Times]{x1D723}}\)\(\def\biLambda{\unicode[Times]{x1D726}}\)\(\def\biXi{\unicode[Times]{x1D729}}\)\(\def\biPi{\unicode[Times]{x1D72B}}\)\(\def\biSigma{\unicode[Times]{x1D72E}}\)\(\def\biUpsilon{\unicode[Times]{x1D730}}\)\(\def\biPhi{\unicode[Times]{x1D731}}\)\(\def\biPsi{\unicode[Times]{x1D733}}\)\(\def\biOmega{\unicode[Times]{x1D734}}\)\((P = 0.012; - 13\% \)) and BCEA \((P = 0.005; - 16\% )\) were smaller, while SRR was greater (\(P = 0.018; + 16\% \)). There was a significant correlation between the intereye difference in BCEA, and differences in MD values (\({\rm{Spearman^{\prime} s}}\ r = 0.65;P = 0.01\)), while differences in SRR were associated with differences in visual acuity (\({\rm{Spearman^{\prime} s}}\ r = 0.64;P = 0.01\)). Furthermore, between-eye differences in BCEA were a significant predictor of between-eye differences in MD: for every 1-dB difference in MD, BCEA reduced by 6.2% (95% confidence interval, 1.6%-10.3%).Eye movements are altered by visual field loss, and these changes are related to changes in clinical measures. Eye movements recorded while passively viewing images could potentially be used as biomarkers for visual field damage.

Capsule Migrant Willow Warblers occupy more woodland types and occur at higher densities than ecologically‐similar resident Afrotropical warblers. Aims To compare population densities of Willow Warblers and eremomelas in adjacent acacia, mopane and miombo woodlands, and assess the abundance of potential invertebrate prey in each habitat type, in order to investigate whether Palearctic migrants use more open habitats and are more flexible in habitat use than their Afrotropical counterparts in the same feeding guild. Methods Using distance sampling we carried out four replicated sets of point counts in acacia woodland and three sets of counts in miombo and mopane between December 1999 and February 2000. We noted the tree species in which we saw warblers foraging and took beating‐tray samples of potential arthropod prey present on tree foliage in each of the three habitats. Results Willow Warbler density in acacia woodland increased from 1.80 ± 0.54 (se) birds/ha in early December to 7.15 ± 1.41 birds/ha in ...