Development of sampling efficiency and internal noise in motion detection and discrimination in school-aged children

AbstractThe aim of this study was to use an equivalent noise paradigm to investigate the development and maturation of motion perception, and how the underlying limitations of sampling efficiency and internal noise effect motion detection and direction discrimination in school-aged children (5–14years) and adults. Contrast energy thresholds of a 2c/deg sinusoidal grating drifting at 1.0 or 6.0Hz were measured as a function of added dynamic noise in three tasks: detection of a drifting grating; detection of the sum of two oppositely drifting gratings and direction discrimination of oppositely drifting gratings. Compared to the ideal observer, in both children and adults, the performance for all tasks was limited by reduced sampling efficiency and internal noise. However, the thresholds for discrimination of motion direction and detection of moving gratings show very different developmental profiles. Motion direction discrimination continues to improve after the age of 14years due to an increase in sampling efficiency that differs with speed. Motion detection and summation were already mature at the age of 5years, and internal noise was the same for all tasks. These findings were confirmed in a 1-year follow-up study on a group of children from the initial study. The results support suggestions that the detection of a moving pattern and discriminating motion direction are processed by different systems that may develop at different rates

Acuity, crowding, reading and fixation stability

AbstractPeople with age-related macular disease frequently experience reading difficulty that could be attributed to poor acuity, elevated crowding or unstable fixation associated with peripheral visual field dependence. We examine how the size, location, spacing and instability of retinal images affect the visibility of letters and words at different eccentricities. Fixation instability was simulated in normally sighted observers by randomly jittering single or crowded letters or words along a circular arc of fixed eccentricity. Visual performance was assessed at different levels of instability with forced choice measurements of acuity, crowding and reading speed in a rapid serial visual presentation paradigm. In the periphery: (1) acuity declined; (2) crowding increased for acuity- and eccentricity-corrected targets; and (3), the rate of reading fell with acuity-, crowding- and eccentricity-corrected targets. Acuity and crowding were unaffected by even high levels of image instability. However, reading speed decreased with image instability, even though the visibility of the component letters was unaffected. The results show that reading performance cannot be standardised across the visual field by correcting the size, spacing and eccentricity of letters or words. The results suggest that unstable fixation may contribute to reading difficulties in people with low vision and therefore that rehabilitation may benefit from fixation training

Development of radial optic flow pattern sensitivity at different speeds

AbstractThe development of sensitivity to radial optic flow discrimination was investigated by measuring motion coherence thresholds (MCTs) in school-aged children at two speeds. A total of 119 child observers aged 6–16years and 24 young adult observers (23.66+/−2.74years) participated. In a 2AFC task observers identified the direction of motion of a 5° radial (expanding vs. contracting) optic flow pattern containing 100 dots with 75% Michelson contrast moving at 1.6°/s and 5.5°/s and. The direction of each dot was drawn from a Gaussian distribution whose standard deviation was either low (similar directions) or high (different directions). Adult observers also identified the direction of motion for translational (rightward vs. leftward) and rotational (clockwise vs. anticlockwise) patterns. Motion coherence thresholds to radial optic flow improved gradually with age (linear regression, p<0.05), with different rates of development at the two speeds. Even at 16years MCTs were higher than that for adults (independent t-tests, p<0.05). Both children and adults had higher sensitivity at 5.5°/s compared to 1.6°/s (paired t-tests, p<0.05). Sensitivity to radial optic flow is still immature at 16years of age, indicating late maturation of higher cortical areas. Differences in sensitivity and rate of development of radial optic flow at the different speeds, suggest that different motion processing mechanisms are involved in processing slow and fast speeds

Sources of Motion-Sensitivity Loss in Glaucoma

International audienc

Studentaktive vurderingsformer i norsk lærer- og optometriutdanning

Medstudentvurdering er en form for studentarbeid som er blitt tatt i bruk og forsket på i større omfang internasjonalt enn nasjonalt. Her presenteres to casestudier med bruk av medstudentvurdering fra to ulike profesjonsutdanninger i Norge: optikerutdanningen ved avdeling for optometri- og synsvitenskap og lærerutdanningen ved avdeling for lærerutdanning ved Høgskolen i Buskerud. Kombinasjonen medstudentvurdering og egenvurdering ble også prøvd ut. Artikkelen belyser erfaringer og utfordringer i forbindelse med planlegging og gjennomfø-ring samt analyse og diskusjon av studentenes evaluering av medstu-dentvurdering

Stroke and vision : special topic call for papers

Call for papers for special issue on vision and stroke  Development of new knowledge in complex areas such as sequelae caused by stroke requires multifaceted and creative research. SJOVS therefore want to invite a broad range of researchers from all corners of the world to submit their manuscripts to be published in open access online within the special topic vision and stroke, and brain damage due to other causes. Topics may include, but are not limited to: - the best way of organising post stroke vision care, patients’ perspectives of living with post stroke visual impairments, - effective treatments and vision rehabilitation, - interdisciplinary interventions that include vision rehabilitation, innovative technological solutions for vision assessment and training, - how to raise awareness for vision issues among patients, and health care personnel. We encourage translational research, with a variety of methodologies, including qualitative, quantitative, mixed methods, or reviews to share knowledge about vision and stroke.  Torgeir Solberg Mathisen Guest Editor  António Filipe Macedo Associate Editor  Helle K. Falkenberg Associate Editor Call for papers för specialutgåva om syn och stroke  Utveckling av ny kunskap inom komplexa områden som t.ex. följdsjukdomar orsakade av stroke kräver mångfacetterad och kreativ forskning. SJOVS vill därför bjuda in ett brett spektrum av forskare från världens alla hörn att skicka in sina manuskript för publicering i open access online inom specialämnet vision and stroke, and brain damage due to other causes. Ämnena kan inkludera, men är inte begränsade till: - det bästa sättet att organisera synvård efter stroke, patienters perspektiv på att leva med synnedsättning efter stroke, - effektiva behandlingar och synrehabilitering, - tvärvetenskapliga insatser som inkluderar synrehabilitering, innovativa tekniska lösningar för synbedömning och synträning, - hur man kan öka medvetenheten om synfrågor bland patienter och vårdpersonal. Vi uppmuntrar translationell forskning med en mängd olika metoder, inklusive kvalitativa, kvantitativa, blandade metoder eller översikter för att dela kunskap om syn och stroke.  Torgeir Solberg Mathisen Gästredaktör  António Filipe Macedo Biträdande redaktör  Helle K. Falkenberg biträdande redaktör Chamada de artigos para edição especial sobre visão e AVC  O desenvolvimento de novos conhecimentos em áreas complexas como as sequelas causadas pelo AVC requer uma investigação multifacetada e criativa. Por conseguinte, o SJOVS pretende convidar um vasto leque de investigadores de todos os cantos do mundo a submeterem os seus manuscritos para publicação em linha de acesso livre no âmbito do tópico especial sobre visão e AVC e lesões cerebrais devidas a outras causas. Os tópicos podem incluir, mas não estão limitados a: - a melhor forma de organizar os cuidados com a visão após o AVC, as perspectivas dos doentes de viver com deficiências visuais após o AVC, - tratamentos eficazes e reabilitação da visão, - intervenções interdisciplinares que incluam a reabilitação da visão, soluções tecnológicas inovadoras para avaliação e treino da visão, - como sensibilizar os doentes e o pessoal de saúde para as questões da visão. Incentivamos a investigação translacional, com uma variedade de metodologias, incluindo métodos qualitativos, quantitativos, mistos ou revisões para partilhar conhecimentos sobre a visão e o AVC.  Torgeir Solberg Mathisen Editor convidado  António Filipe Macedo Editor Associado  Helle K. Falkenberg Editor Associado