Test-retest reliability and practice effect of the Leuven Perceptual Organisation Screening Test.

AbstractVisual diagnostic tests must have a high degree of consistency in their measurements (high reliability) to ensure accurate assessment of perceptual abilities. The current study assessed test-retest reliability and practice effects in the Leuven Perceptual Organisation Screening Test (L-POST) in 144 healthy volunteers, with time intervals between 0 and 756 days. We used Pearson's and intraclass correlation analysis, Bland-Altman analysis and multilevel modelling. Results from our analyses converged and supported an adequate reliability of the L-POST. Multilevel modelling demonstrated an absence of practice effect, suggesting that the L-POST is suitable for repeat administration. This study suggests that the L-POST has adequate reliability and is suitable for repeat administration even at short intervals. This study provides the basis for a more systematic evaluation for neuropsychological assessments, which can lead to the development of more reliable assessment batteries.

Assessment tool for visual perception deficits in cerebral visual impairment: development and normative data of typically developing children.

AIM: To develop an assessment tool that measures a wide range of visual perceptual deficits common in cerebral visual impairment (CVI) and to provide normative data from typically developing children between 3 and 6 years of age. METHOD: Test development reflected cross-talk between vision research and clinical relevance for CVI. The Children's Visual Impairment Test for 3- to 6-year-olds (CVIT 3-6) includes 14 subtests covering four domains of visual perception: Object Recognition, Degraded Object Recognition, Motion Perception, and Global-Local Processing. Normative data were collected from 301 typically developing children (mean age 4y 8mo [SD 9.7mo]; 148 females, 153 males). A questionnaire was administered to parents about pregnancy duration, birth, and developmental problems. RESULTS: Average total CVIT 3-6 performance was 60.1 (SD 5.5) out of 70. The cut-off score for normal visual perception (53) was set at the 10th centile of scores in typically developing children. Multiple regression indicated CVIT 3-6 visual perception scores increase with age for children born at 36 weeks' gestational age or later (ß=-18.03, 95% confidence interval -31.31 to -4.75). INTERPRETATION: CVIT 3-6 is a tool to assess a wide range of visual perceptual deficits common in CVI. Age-dependent normative data are available because we found performance increased with age. WHAT THE PAPER ADDS: A test for visual perceptual deficits common in cerebral visual impairment. Visual perceptual functions improve with age in full-term typically developing children.

HERRAMIENTA DE EVALUACIÓN PARA LAS DEFICIENCIAS DE LA PERCEPCIÓN VISUAL EN LA DISCAPACIDAD VISUAL CEREBRAL: DESARROLLO Y DATOS NORMATIVOS DE NIÑOS CON DESARROLLO TÍPICO: OBJETIVO: Desarrollar una herramienta de evaluación que mida una amplia gama de déficits de percepción visual comunes en la discapacidad visual cerebral (CVI) y proporcionar datos normativos de niños con un desarrollo típico entre los 3 y los 6 años de edad. MÉTODO: El desarrollo de la prueba reflejó la alineación de contenidos entre la investigación de la visión y la relevancia clínica para la CVI. La prueba de discapacidad visual para niños de 3 a 6 años (CVIT 3-6) incluye 14 subpruebas que cubren cuatro dominios de la percepción visual: reconocimiento de objetos, reconocimiento de objetos con fondos borrosos, percepción de movimiento y procesamiento global y local. Se recopilaron datos normativos de 301 niños con desarrollo típico (edad promedio 4 años y 8 meses [DS 9,7 meses]; 148 mujeres, 153 varones). Se administró un cuestionario a los padres sobre la duración del embarazo, el parto y los problemas de desarrollo. RESULTADOS: El rendimiento promedio total de CVIT 3-6 fue de 60,1 (DS 5,5) sobre 70. El puntaje límite para la percepción visual normal (53) se estableció en el décimo centil de puntajes en niños con un desarrollo típico. La regresión múltiple indicó que las puntuaciones de percepción visual CVIT 3-6 aumentan con la edad para los niños nacidos a las 36 semanas de edad gestacional o más tarde (ß = -18,03, intervalo de confianza del 95% -31,31 a -4,75). INTERPRETACIÓN: CVIT 3-6 es una herramienta para evaluar una amplia gama de déficits de percepción visual comunes en la CVI. Los datos normativos que dependen de la edad están disponibles porque encontramos que el rendimiento aumentó con la edad.

INSTRUMENTO DE AVALIAÇÃO PARA DÉFICITS DE PERCEPÇÃO VISUAL NA DEFICIÊNCIA VISUAL CEREBRAL: DESENVOLVIMENTO E DADOS NORMATIVOS DE CRIANÇAS COM DESENVOLVIMENTO TÍPICO: OBJETIVO: Desenvolver um instrumento de avaliação que mensure uma variedade de déficits de percepção visual comuns na deficiência visual cerebral (DVC) e fornecer dados normativos de crianças com desenvolvimento típcico entre 3 e 6 anos de idade. MÉTODO: O desenvolvimento do teste refletiu a comunicação entre pesquisas relacionadas à visão e a relevância clínica para a DVC. O Teste da Deficiência Visual para Crianças direcionado para a população de 3 a 6 anos de idade (TDVC-3-6) inclui 14 subtestes que cobrem quatro domínios da percepção visual: reconhecimento de objetos, reconhecimento de objetos diminuída, percepção de movimento, e processamento global-local. Dados normativos foram coletados em 301 crianças com desenvolvimento típico (média de idade 4a 8m [DP 9,7 m]; 148 do sexo feminino, 153 do sexo masculino). Um questionário foi administrado aos pais sobre a duração da gestação, nascimento e problemas relacionados ao desenvolvimento. RESULTADOS: O desempenho médio total no TDVC 3-6 foi 60,1 (DP 5,5) em um total de 70. O escore de corte para percepção visual normal (53) foi estabelecido como o 10o. percentil de escores em crianças com desenvolvimento típico. Regressão múltipla indicou que escores de percepção do TDVC 3-6 aumentam com a idade para crianças nascidas com 36 semanas de idade gestacional ou mais (ß=-18,03, 95% intervalo de confiança -31,31 a -4,75). INTERPRETAÇÃO: O TDVC 3-6 é um instrumento para avaliar uma variedade de déficits da percepção visual comuns em DVC. Dados normativos relacionados à idade estão disponíveis, pois observamos que o desempenho aumentou com a idade.

Assessment tool for visual perception deficits in cerebral visual impairment: reliability and validity.

AIM: To evaluate the reliability and validity of the Children's Visual Impairment Test for 3- to 6-year-olds (CVIT 3-6). METHOD: Reliability was assessed via test-retest correlation and intraclass correlation coefficient (ICC) in typically developing children, children with cerebral visual impairment (CVI), intellectual impairment, and simulated impaired vision (validation groups n=59, mean developmental age=4y 10mo, 27 females, 32 males). Internal validity was evaluated with a confirmatory factor analysis on the normative sample (n=301, median age=4y 8mo, SD=9.7mo, 148 females, 153 males). External validity was assessed by correlating performance on CVIT 3-6 with L94, the Beery-Buktenica Developmental Test of Visuo-Motor Integration (Beery-VMI), the Freiburg Vision Test, the revised Snijders-Oomen Nonverbal Intelligence Test for children between 2 years 6 months and 7-years-old (SON-R 2.5-7), and the Social Responsiveness Scale (SRS) questionnaire and by comparing performance between validation groups. RESULTS: We observed very good test-retest reliability (r=0.82, p<0.001, ICC=0.80) and confirmed the hypothesized factor structure (comparative fit index=1; Tucker-Lewis index=1.045). We found high correlations with tests with a strong visual perception component (L94: r=0.74, p<0.001; SON-R 2.5-7: r=0.37, p=0.01) and low correlations with other tests (Beery-VMI: r=0.25, p=0.09; SRS: r=0-0.26, p=0.09). Lowest scores were observed for children with CVI compared to the other validation groups (F[3,44]=5.1, p=0.003). INTERPRETATION: CVIT 3-6 is grounded in knowledge of visual perception. The tool specifically measures CVI-related visual perception deficits and is not mediated by intellectual abilities or low visual acuity. WHAT THE PAPER ADDS: Evidence for good test-retest reliability of the Children's Visual Impairment Test for 3- to 6-year-olds (CVIT 3-6). Factor structure of normative data reflects CVIT 3-6's foundations in vision science. CVIT 3-6 specifically measures visual perception impairments. CVIT 3-6 performance is not influenced by intelligence or low visual acuity.

Visuoperceptual profiles of children using the Flemish cerebral visual impairment questionnaire.

AIM: To investigate the underlying factor structure of the 46-item Flemish cerebral visual impairment (CVI) questionnaire, differentiate the factor scores of children with and without CVI, and examine the impact of comorbidities on factor scores. METHOD: The records of 630 children (386 males, 244 females; median age 77mo; interquartile range 63-98mo) who visited the CVI clinic and the Centre for Developmental Disabilities at the University Hospitals of Leuven from 2001 to 2018 were reviewed systematically. Inclusion criteria included an up-to-date questionnaire, a definitive diagnosis, and clinical assessment. RESULTS: Three hundred and forty-five children (179 with CVI [108 males, 71 females; median age 74mo; interquartile range 61-93mo] and 166 without CVI [110 males, 56 females; median age 88mo; interquartile range 70-107mo]) were included. An exploratory factor analysis resulted in a 5-factor (object and face processing impairments; visual (dis)interest; clutter and distance viewing impairments; moving in space impairments; and anxiety-related behaviours) biologically and clinically plausible model, which retained 35 items and explained 56% of the total variance. Mann-Whitney U tests indicated that factors 1 to 4 were significantly higher in children with CVI compared to children without CVI (p-values ranged from p<0.001 to p<0.05; effect sizes ranged from 0.11 to 0.33); factor 5 showed no differences. Autism, developmental coordination disorder, epilepsy, and cerebral palsy impacted factor scores. INTERPRETATION: A 5-factor structure of the Flemish CVI questionnaire differentiates children with and without CVI. Comorbidities should be accounted for when researching CVI. WHAT THIS PAPER ADDS: Cerebral visual impairment (CVI) is characterized by impaired object and face processing and impaired visual interest. CVI is also characterized by impaired clutter and distance viewing, and impaired moving in space. All children (with or without CVI) demonstrated anxiety-related behaviours. Autism affected object/face processing, whereas developmental coordination disorder, epilepsy, and cerebral palsy affected visual interest.

Perfis visuoperceptuais de crianças usando o questionário Flemish de deficiência visual cerebral OBJETIVOS: Investigar a estrutura de fator do questionário Flemish de deficiência visual cerebral (DVC) com 46 itens, diferenciar os escores de fator de crianças com e sem DVC, e examinar o impacto de comorbidades nos escores de fator. MÉTODO: Os prontuários de 630 crianças (386 do sexo masculino, 244 do sexo feminino; idade mediana 77m; intervalo interquartil 63-98m;) que visitaram a clínica de DVC e o Centro para Desordens do Desenvolvimento nos Hospitais Universitários de Leuven de 2001 a 2018 foram sistematicamente revisados. Os critérios de inclusão foram um questionário atualizado, um diagnóstico definitivo, e uma avaliação clínica. RESULTADOS: Trezentas e quarenta e cinco crianças (179 com DVC [108 do sexo masculino, 71 do sexo feminino; idade mediana 74m; intervalo interquartil 61-93m] e 166 sem DVC [110 do sexo masculino, 56 do sexo feminino; idade mediana 88m; intervalo interquartil 70-107m]) foram incluídas. Uma análise exploratória de fator resultou em um modelo com 5 fatores (deficiências no processamento de objeto e face; (des)interesse visual; deficiências na visão de espaços abarrotados e distância; deficiências na movimentação no espaço; e comportamentos relacionados a ansiedade) biológica e clinicamente plausível, que reteve 35 itens e explicou 56% da variância total. Os testes U de Mann-Whitney indicaram que fatores de 1 a 4 foram significativamente mais altos nas crianças com DVC comparadas com aquelas sem (valores de p variaram de p<0,001 a p<0,05; os tamanhos de efeito variaram de 0,11 a 0,33); o fator 5 não mostrou diferenças. Autismo, transtorno do desenvolvimento da coordenação, epilepsia e paralisia cerebral impactaram os escores de fator. INTERPRETAÇÃO: Uma estrutura com 5 fatores do questionário Flemish para DVC diferencia crianças com e sem DVC. Comorbidades devem ser consideradas quando se pesquisar a DVC.

Perfis visuoperceptuais de crianças usando o questionário Flemish de deficiência visual cerebral OBJETIVOS: Investigar a estrutura de fator do questionário Flemish de deficiência visual cerebral (DVC) com 46 itens, diferenciar os escores de fator de crianças com e sem DVC, e examinar o impacto de comorbidades nos escores de fator. MÉTODO: Os prontuários de 630 crianças (386 do sexo masculino, 244 do sexo feminino; idade mediana 77m; intervalo interquartil 63-98m;) que visitaram a clínica de DVC e o Centro para Desordens do Desenvolvimento nos Hospitais Universitários de Leuven de 2001 a 2018 foram sistematicamente revisados. Os critérios de inclusão foram um questionário atualizado, um diagnóstico definitivo, e uma avaliação clínica. RESULTADOS: Trezentas e quarenta e cinco crianças (179 com DVC [108 do sexo masculino, 71 do sexo feminino; idade mediana 74m; intervalo interquartil 61-93m] e 166 sem DVC [110 do sexo masculino, 56 do sexo feminino; idade mediana 88m; intervalo interquartil 70-107m]) foram incluídas. Uma análise exploratória de fator resultou em um modelo com 5 fatores (deficiências no processamento de objeto e face; (des)interesse visual; deficiências na visão de espaços abarrotados e distância; deficiências na movimentação no espaço; e comportamentos relacionados a ansiedade) biológica e clinicamente plausível, que reteve 35 itens e explicou 56% da variância total. Os testes U de Mann-Whitney indicaram que fatores de 1 a 4 foram significativamente mais altos nas crianças com DVC comparadas com aquelas sem (valores de p variaram de p<0,001 a p<0,05; os tamanhos de efeito variaram de 0,11 a 0,33); o fator 5 não mostrou diferenças. Autismo, transtorno do desenvolvimento da coordenação, epilepsia e paralisia cerebral impactaram os escores de fator. INTERPRETAÇÃO: Uma estrutura com 5 fatores do questionário Flemish para DVC diferencia crianças com e sem DVC. Comorbidades devem ser consideradas quando se pesquisar a DVC.

Overestimation of stereo thresholds by the TNO stereotest is not due to global stereopsis.

PURPOSE: It has been repeatedly shown that the TNO stereotest overestimates stereo threshold compared to other clinical stereotests. In the current study, we test whether this overestimation can be attributed to a distinction between 'global' (or 'cyclopean') and 'local' (feature or contour-based) stereopsis. METHODS: We compared stereo thresholds of a global (TNO) and a local clinical stereotest (Randot Circles). In addition, a global and a local psychophysical stereotest were added to the design. One hundred and forty-nine children between 4 and 16 years old were included in the study. RESULTS: Stereo threshold estimates with TNO were a factor of two higher than with any of the other stereotests. No significant differences were found between the other tests. Bland-Altman analyses also indicated low agreement between TNO and the other stereotests, especially for higher stereo threshold estimates. Simulations indicated that the TNO test protocol and test disparities can account for part of this effect. DISCUSSION: The results indicate that the global - local distinction is an unlikely explanation for the overestimated thresholds of TNO. Test protocol and disparities are one contributing factor. Potential additional factors include the nature of the task (TNO requires depth discrimination rather than detection) and the use of anaglyph red/green 3D glasses rather than polarizing filters, which may reduce binocular fusion.

Avoiding monocular artifacts in clinical stereotests presented on column-interleaved digital stereoscopic displays.

New forms of stereoscopic 3-D technology offer vision scientists new opportunities for research, but also come with distinct problems. Here we consider autostereo displays where the two eyes' images are spatially interleaved in alternating columns of pixels and no glasses or special optics are required. Column-interleaved displays produce an excellent stereoscopic effect, but subtle changes in the angle of view can increase cross talk or even interchange the left and right eyes' images. This creates several challenges to the presentation of cyclopean stereograms (containing structure which is only detectable by binocular vision). We discuss the potential artifacts, including one that is unique to column-interleaved displays, whereby scene elements such as dots in a random-dot stereogram appear wider or narrower depending on the sign of their disparity. We derive an algorithm for creating stimuli which are free from this artifact. We show that this and other artifacts can be avoided by (a) using a task which is robust to disparity-sign inversion-for example, a disparity-detection rather than discrimination task-(b) using our proposed algorithm to ensure that parallax is applied symmetrically on the column-interleaved display, and (c) using a dynamic stimulus to avoid monocular artifacts from motion parallax. In order to test our recommendations, we performed two experiments using a stereoacuity task implemented with a parallax-barrier tablet. Our results confirm that these recommendations eliminate the artifacts. We believe that these recommendations will be useful to vision scientists interested in running stereo psychophysics experiments using parallax-barrier and other column-interleaved digital displays.

The Leuven Perceptual Organization Screening Test (L-POST), an online test to assess mid-level visual perception.

Neuropsychological diagnostic tests of visual perception mostly assess high-level processes like object recognition. Object recognition, however, relies on distinct mid-level processes of perceptual organization that are only implicitly tested in classical tests. The Leuven Perceptual Organization Screening Test (L-POST) fills a gap with respect to clinically oriented tests of mid-level visual function. In 15 online subtests, a range of mid-level processes are covered, such as figure-ground segmentation, local and global processing, and shape perception. We also test the sensitivity to a wide variety of perceptual grouping cues, like common fate, collinearity, proximity, and closure. To reduce cognitive load, a matching-to-sample task is used for all subtests. Our online test can be administered in 20-45 min and is freely available at www.gestaltrevision.be/tests . The online implementation enables us to offer a separate interface for researchers and clinicians to have immediate access to the raw and summary results for each patient and to keep a record of their patient's entire data. Also, each patient's results can be flexibly compared with a range of age-matched norm samples. In conclusion, the L-POST is a valuable screening test for perceptual organization. The test allows clinicians to screen for deficits in visual perception and enables researchers to get a broader overview of mid-level visual processes that are preserved or disrupted in a given patient.

Impaired texture segregation but spared contour integration following damage to right posterior parietal cortex.

We examined the relations between texture segregation and contour integration in patients with deficits in spatial attention leading to left or right hemisphere extinction. Patients and control participants were presented with texture and contour stimuli consisting of oriented elements. We induced regularity in the stimuli by manipulating the element orientations resulting in an implicit texture border or explicit contour. Participants had to discriminate curved from straight shapes without making eye movements, while the stimulus presentation time was varied using a QUEST procedure. The results showed that only patients with right hemisphere extinction had a spatial bias, needing a longer presentation time to determine the shape of the border or contour on the contralesional side, especially for borders defined by texture. These results indicate that texture segregation is modulated by attention-related brain areas in the right posterior parietal cortex.

Current practice and challenges in screening for visual perception deficits after stroke: a qualitative study.

PURPOSE: We document current clinical practice and needs in screening for visual perception problems after stroke to inform development of new screening tools. MATERIALS AND METHODS: We interviewed 12 occupational therapists and 13 orthoptists. Interviews were thematically analysed using the Value Proposition Canvas, a model which establishes challenges and facilitators in what people want to achieve. RESULTS: Participants' understanding of visual perception varied and often included sensory and cognitive deficits. Occupational therapists commonly screened for visual field deficits and hemispatial neglect, while other aspects of visual cognition were rarely assessed. A positive screening result triggered an orthoptic referral. Screening generally occurred during functional assessments and/or with in-house developed tools. Challenges to practice were: lack of time, lack of training, environmental and stroke survivor factors (e.g., aphasia), insufficient continuation of care, and test characteristics (e.g., not evidence-based). Facilitators were: quick and practical tools, experienced staff or tools with minimal training requirements, a streamlined care pathway. CONCLUSIONS: Screening employs non-standardised assessments and rarely covers higher visual perceptual deficits. We demonstrates the need for an evidence-based visual perception screen, which should ideally be 15 min or less, be portable, and require minimal equipment. The screen should be suitable for bedside testing and aphasia-friendly.Implications for rehabilitationThere is a high demand for training on what visual perception deficits are and how to screen for them.Building local relationships between orthoptists and occupational therapists is perceived as highly beneficial for providing good vision and visual perception care for stroke survivors.Occupational therapists should be alert for visual perceptual deficits in their patients preferably through systematic screening with standardised assessments such as the shortened version of the Rivermead Perceptual Assessment Battery or Occupational Therapy Adult Perceptual Screening Test.

Visual perceptual deficit screening in stroke survivors: evaluation of current practice in the United Kingdom and Republic of Ireland.

PURPOSE: Visual perceptual deficits are frequently underdiagnosed in stroke survivors compared to sensory vision deficits or visual neglect. To better understand this imparity, we evaluated current practice for screening post-stroke visual perceptual deficits. METHODS: We conducted a survey targeted at professionals working with stroke survivors involved in screening visual perceptual deficits across the United Kingdom and the Republic of Ireland. RESULTS: Forty orthoptists and 174 occupational therapists responded to the survey. Visual perceptual deficit screening was primarily conducted by occupational therapists (94%), with 75∼100% of stroke survivors screened per month. Respondents lacked consensus on whether several common post-stroke visual deficits were perceptual or not. During the screening, respondents primarily relied on self-reports and observation (94%), while assessment batteries (58%) and screening tools were underutilised (56%) and selected inappropriately (66%). Respondents reported lack of training in visual perception screening (20%) and physical/cognitive condition of stroke survivors (19%) as extremely challenging during screening. CONCLUSIONS: Visual perceptual deficits are screened post-stroke at a similar rate to sensory vision or visual neglect. Underdiagnosis of visual perceptual deficits may stem from both reliance on subjective and non-standardised screening approaches, and conflicting definitions of visual perception held among clinicians. We recommend increased training provision and use of brief performance-based screening tools.IMPLICATIONS FOR REHABILITATIONLack of agreement among clinicians on what constitutes as visual perceptual or sensory vision deficits may prove problematic, as precise and exact language is often required for clinical decision-making (e.g., referrals).Biases for more familiar visual (perceptual) deficits held among clinicians during the screening process may lead to other visual deficits being missed.To avoid problems being missed, clinicians should aim to use standardised assessments rather than stroke survivor self-report and observations of function when screening for visual perceptual difficulties.

Shortening the Leuven Perceptual Organization Screening Test with item response theory and confirmatory factor analysis.

The Leuven Perceptual Organization Screening Test (L-POST) is a test for midlevel visual perceptual deficits after brain injury. Previous research demonstrated reliable test scores and valid test score interpretations. However, the test's duration (20-35 min) is too long for a screening approach for all patients in clinical practice. Our aim was to shorten L-POST to 10-15 min based on statistical criteria of the items. Data from 3,391 participants who completed L-POST were analyzed. L-POST consists of 15 subtests with five items each. Item Response Theory (IRT) was applied to guide the selection of the items. The highest correlation with full-scale subtest scores was observed when two items were selected for each subtest following an adaptive testing procedure. A pilot validation in a subsample of participants with low abilities demonstrated adaptive testing has reasonable sensitivity (80%) but limited specificity (55%) in classifying participants with impaired and unimpaired abilities. Subsequently, we reduced the number of subtests through factor analysis. We showed that the subtests using Radial Frequency Patterns as stimuli were redundant and could be combined in one subtest. We conclude that L-POST can be shortened to 26 items (7-14 min) and an adaptive item selection procedure could prove particularly useful for screening purposes. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Recovery of Visuospatial Neglect Subtypes and Relationship to Functional Outcome Six Months After Stroke.

Background/Objective. This study aims to investigate how complex visuospatial neglect behavioural phenotypes predict long-term outcomes, both in terms of neglect recovery and broader functional outcomes after 6 months post-stroke. Methods. This study presents a secondary cohort study of acute and 6-month follow-up data from 400 stroke survivors who completed the Oxford Cognitive Screen's Cancellation Task. At follow-up, patients also completed the Stroke Impact Scale questionnaire. These data were analysed to identify whether any specific combination of neglect symptoms is more likely to result in long-lasting neglect or higher levels of functional impairment, therefore warranting more targeted rehabilitation. Results. Overall, 98/142 (69%) neglect cases recovered by follow-up, and there was no significant difference in the persistence of egocentric/allocentric (X2 [1] = .66 and P = .418) or left/right neglect (X2 [2] = .781 and P = .677). Egocentric neglect was found to follow a proportional recovery pattern with all patients demonstrating a similar level of improvement over time. Conversely, allocentric neglect followed a non-proportional recovery pattern with chronic neglect patients exhibiting a slower rate of improvement than those who recovered. A multiple regression analysis revealed that the initial severity of acute allocentric, but not egocentric, neglect impairment acted as a significant predictor of poor long-term functional outcomes (F [9,300] = 4.742, P < .001 and adjusted R2 = .098). Conclusions. Our findings call for systematic neuropsychological assessment of both egocentric and allocentric neglect following stroke, as the occurrence and severity of these conditions may help predict recovery outcomes over and above stroke severity alone.

[Formula: see text] Quantifying visuoperceptual profiles of children with cerebral visual impairment.

The aim was to develop a visuoperceptual profile schema reflecting visuoperceptual strengths and weaknesses, using neuropsychological tests. Secondly, this schema was used to quantify individual visuoperceptual profiles of children with and without cerebral visual impairment (CVI), and to identify differences in their profiles. Clinical records (2001-2018) of 630 children (386 males, 244 females; median age 77 months; interquartile range 63-98 months) suspected for CVI were reviewed. Neurological history, visuoperceptual results, ophthalmological, and neuroimaging data were retrieved. To develop the visuoperceptual schema, exploratory factor analyses (EFAs) were performed, followed by a Delphi study. In individual interviews, six experts were asked to "name the different visuoperceptual dimensions" and "what visuoperceptual dimensions are targeted by each of the 24 visuoperceptual subtests." To reach consensus, two questionnaire rounds (44 statements and 20 statements, respectively, five experts) followed. EFAs showed clinically uninterpretable results. The Delphi study revealed seven visuoperceptual dimensions; (1) visual discrimination and matching, (2) object or picture recognition, (3) visual spatial perception, (4) figure-ground perception, (5) motion perception, (6) visual short-term memory, and (7) scene perception. The most discriminating dimensions between CVI and no CVI were object/picture recognition (r = 0.56), visual spatial perception (r = 0.52), visual discrimination and matching (r = 0.47), and figure-ground perception (r = 0.39). Motion perception and visual short-term memory (both r = 0.22) were less discriminating. Two case studies illustrate how to apply the visuoperceptual schema to characterize dysfunction and intact functions. Visuoperceptual profiling can serve as a basis for individualized therapies in heterogeneous disorders.

Stereotest Comparison: Efficacy, Reliability, and Variability of a New Glasses-Free Stereotest.

Purpose: To test the validity of the ASTEROID stereotest as a clinical test of depth perception by comparing it to clinical and research standard tests. Methods: Thirty-nine subjects completed four stereotests twice: the ASTEROID test on an autostereo 3D tablet, a research standard on a VPixx PROPixx 3D projector, Randot Circles, and Randot Preschool. Within 14 days, subjects completed each test for a third time. Results: ASTEROID stereo thresholds correlated well with research standard thresholds (r = 0.87, P < 0.001), although ASTEROID underestimated standard threshold (mean difference = 11 arcsec). ASTEROID results correlated less strongly with Randot Circles (r = 0.54, P < 0.001) and Randot Preschool (r = 0.64, P < 0.001), due to the greater measurement range of ASTEROID (1-1000 arcsec) compared to Randot Circles or Randot Preschool. Stereo threshold variability was low for all three clinical stereotests (Bland-Altman 95% limits of agreement between test and retest: ASTEROID, ±0.37; Randot Circles, ±0.24; Randot Preschool, ±0.23). ASTEROID captured the largest range of stereo in a normal population with test-retest reliability comparable to research standards (immediate r = 0.86 for ASTEROID vs. 0.90 for PROPixx; follow-up r = 0.68 for ASTEROID vs. 0.88 for PROPixx). Conclusions: Compared to clinical and research standards for assessing depth perception, ASTEROID is highly accurate, has good test-retest reliability, and measures a wider range of stereo threshold. Translational Relevance: The ASTEROID stereotest is a better clinical tool for determining baseline stereopsis and tracking changes during treatment for amblyopia and strabismus compared to current clinical tests.

The impact of active research involvement of young children in the design of a new stereotest.

BACKGROUND: Although considered important, the direct involvement of young children in research design is scarce and to our knowledge its impact has never been measured. We aim to demonstrate impact of young children's involvement in improving the understanding of a new 3D eye test or stereotest. METHODS: After a pre-measure of understanding was taken, we explored issues with the test instructions in patient and public involvement (PPI) sessions where children acted as advisers in the test design. Feedback was collected via observations, rating scales and verbal comments. An interdisciplinary panel reviewed the feedback, discussed potential changes to the test design, and decided on the implementation. Subsequently, a post-measure of understanding (Study 1-2) and engagement (Study 3) was collected in a pre-post study design. Six hundred fifty children (2-11.8 years old) took part in the pre-measure, 111 children (1-12 years old) in the subsequent PPI sessions, and 52 children (4-6 years old) in the first post-measure. One hundred twenty-two children (1-12 years old) and unrelated adults took then part in a second series of PPI sessions, and 53 people (2-39 years old) in the final post-measure. Adults were involved to obtain verbal descriptions of the target that could be used to explain the task to children. RESULTS: Following feedback in Study 1, we added a frame cue and included a shuffle animation. This increased the percentage of correct practice trials from 76 to 97% (t (231) = 14.29, p < .001), but more encouragements like 'Keep going!' were needed (t (64) = 8.25, p < .001). After adding a cardboard demo in Study 2, the percentage of correct trials remained stable but the number of additional instructions given decreased (t (103) = 3.72, p < .001) as did the number of encouragements (t (103) = 8.32, p < .001). Therefore, changes in test design following children's feedback significantly improved task understanding. CONCLUSIONS: Our study demonstrates measurable impact of involvement of very young children in research design through accessible activities. The changes implemented following their feedback significantly improved the understanding of our test. Our approach can inform researchers on how to involve young children in research design and can contribute to developing guidelines for involvement of young children in research.

Efficient estimation of stereo thresholds: What slope should be assumed for the psychometric function?

Bayesian staircases are widely used in psychophysics to estimate detection thresholds. Simulations have revealed the importance of the parameters selected for the assumed subject's psychometric function in enabling thresholds to be estimated with small bias and high precision. One important parameter is the slope of the psychometric function, or equivalently its spread. This is often held fixed, rather than estimated for individual subjects, because much larger numbers of trials are required to estimate the spread as well as the threshold. However, if this fixed value is wrong, the threshold estimate can be biased. Here we determine the optimal slope to minimize bias and maximize precision when measuring stereoacuity with Bayesian staircases. We performed 2- and 4AFC disparity detection stereo experiments in order to measure the spread of the disparity psychometric function in human observers assuming a Logistic function. We found a wide range, between 0.03 and 3.5 log10 arcsec, with little change with age. We then ran simulations to examine the optimal spread using the empirical data. From our simulations and for three different experiments, we recommend selecting assumed spread values between the percentiles 60-80% of the population distribution of spreads (these percentiles can be extended to other type of thresholds). For stereo thresholds, we recommend a spread around the value σ = 1.7 log10 arcsec for 2AFC (slope ß = 4.3 /log10 arcsec), and around σ = 1.5 log10 arcsec for 4AFC (ß = 4.9 /log10 arcsec). Finally, we compared a Bayesian procedure (ZEST using the optimal σ) with five Bayesian procedures that are versions of ZEST-2D, Psi, and Psi-marginal. In general, for the conditions tested, ZEST optimal σ showed the lowest threshold bias and highest precision.

Discrimination of locomotion direction in impoverished displays of walkers by macaque monkeys.

A vast literature exists on human biological motion perception in impoverished displays, e.g., point-light walkers. Less is known about the perception of impoverished biological motion displays in macaques. We trained 3 macaques in the discrimination of facing direction (left versus right) and forward versus backward walking using motion-capture-based locomotion displays (treadmill walking) in which the body features were represented by cylinder-like primitives. The displays did not contain translatory motion. Discriminating forward versus backward locomotion requires motion information while the facing-direction/view task can be solved using motion and/or form. All monkeys required lengthy training to learn the forward-backward task, while the view task was learned more quickly. Once acquired, the discriminations were specific to walking and stimulus format but generalized across actors. Although the view task could be solved using form cues, there was a small impact of motion. Performance in the forward-backward task was highly susceptible to degradations of spatiotemporal stimulus coherence and motion information. These results indicate that rhesus monkeys require extensive training in order to use the intrinsic motion cues related to forward versus backward locomotion and imply that extrapolation of observations concerning human perception of impoverished biological motion displays onto monkey perception needs to be made cautiously.

Which Stereotest do You Use? A Survey Research Study in the British Isles, the United States and Canada.

A wide range of stereotests are available to measure stereopsis. Because each test has its own advantages and disadvantages, opinions differ on which is the preferred test to use in clinical practice. We conducted surveys comparing the use of stereotests in the British Isles and in the United States and Canada. Two online surveys were developed following consultation with eye care professionals, one for each geographical area. Both surveys included two questions on the frequency of use of different stereotests, two questions on best practice stereotests, and two questions on the usefulness of stereotests. Researchers made distinctions between appointments with children below or above 6 years old for respondents from the British Isles and below or above 5 years old for respondents from the Unites Stated and Canada. The surveys were distributed through professional organisations. We found Frisby to be the most used stereotest on the British Isles for both age groups. In the US and Canada, Titmus and Randot stereotest are more frequently used. Respondents consider these tests as the best practice stereotests. Eye care professionals agree stereotests are useful in the diagnosis and treatment decision making and even more so in obtaining an accurate measure of stereoacuity, especially with older children.

Characterizing the Randot Preschool stereotest: Testability, norms, reliability, specificity and sensitivity in children aged 2-11 years.

PURPOSE: To comprehensively assess the Randot Preschool stereo test in young children, including testability, normative values, test/retest reliability and sensitivity and specificity for detecting binocular vision disorders. METHODS: We tested 1005 children aged 2-11 years with the Randot Preschool stereo test, plus a cover/uncover test to detect heterotropia. Monocular visual acuity was assessed in both eyes using Keeler Crowded LogMAR visual acuity test for children aged 4 and over. RESULTS: Testability was very high: 65% in two-year-olds, 92% in three-year-olds and ~100% in older children. Normative values: In 389 children aged 2-5 with apparently normal vision, 6% of children scored nil (stereoblind). In those who obtained a threshold, the mean log threshold was 2.06 log10 arcsec, corresponding to 114 arcsec, and the median threshold was 100 arcsec. Most older children score 40 arcsec, the best available score. We found a small sex difference, with girls scoring slightly but significantly better. Test/retest reliability: ~99% for obtaining any score vs nil. Agreement between stereo thresholds is poor in children aged 2-5; 95% limit of agreement = 0.7 log10 arcsec: five-fold change in stereo threshold may occur without any change in vision. In children over 5, the test essentially acts only as a binary classifier since almost all non-stereoblind children score 40 arcsec. Specificity (true negative rate): >95%. Sensitivity (true positive rate): poor, <50%, i.e. around half of children with a demonstrable binocular vision abnormality score well on the Randot Preschool. CONCLUSIONS: The Randot Preschool is extremely accessible for even very young children, and is very reliable at classifying children into those who have any stereo vision vs those who are stereoblind. However, its ability to quantify stereo vision is limited by poor repeatability in children aged 5 and under, and a very limited range of scores relevant to children aged over 5.