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Visual Deficits (visual + deficit)
Selected AbstractsVisual deficits in developmental dyslexia: relationships between non-linguistic visual tasks and their contribution to components of readingDYSLEXIA, Issue 2 2008Manon W. Jones Abstract Developmental dyslexia is often characterized by a visual deficit, but the nature of this impairment and how it relates to reading ability is disputed (Brain 2003; 126: 841,865). In order to investigate this issue, we compared groups of adults with and without dyslexia on the Ternus, visual-search and symbols tasks. Dyslexic readers yielded more errors on the visual-search and symbols tasks compared with non-dyslexic readers. A positive correlation between visual-search and symbols task performance suggests a common mechanism shared by these tasks. Performance on the visual-search and symbols tasks also correlated with non-word reading and rapid automatized naming measures, and visual search contributed independent variance to non-word reading. The Ternus task did not discriminate reading groups nor contributed significant variance to reading measures. We consider how visual-attention processes might underlie specific component reading measures. Copyright © 2007 John Wiley & Sons, Ltd. [source] The value of contrast sensitivity in diagnosing central serous chorioretinopathyCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 4 2007S Plainis MSc PhD A 39-year-old hyperopic male was referred for laser refractive treatment. In the course of the pre-operative evaluation he complained of a recent deterioration of vision. The suspicion of unilateral central serous chorioretinopathy (CSCR) was confirmed by contrast sensitivity testing and by ocular fundus examination. Contrast sensitivity (CS) for six spatial frequencies (1, 2, 4, 8, 12 and 16 c/deg) was evaluated using Gabor patches of gratings projected on a high-resolution display by means of a stimulus generator card. Although VA remained unaltered, the pattern of contrast sensitivity function varied at different stages of CSCR: during the acute stage, performance at all spatial frequencies was depressed, while at two-month follow up, intermediate and high spatial frequencies were mainly affected. It is concluded that the level of visual deficit in CSCR cannot be evaluated by measuring visual acuity. History and contrast sensitivity can play a central role in setting the correct diagnosis and characterising its stage. [source] A visual skills inventory for children with neurological impairmentsDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 10 2007D L McCulloch OD PhD FAAO Children with neurological impairments often have visual deficits that are difficult to quantify. We have compared visual skills evaluated by carers with results of a comprehensive visual assessment. Participants were 76 children with mild to profound intellectual and/or motor impairment (33 males, 43 females; age range 7mo,16y; mean age 5y 1mo [SD 4y 2mo]) who completed a visual skills inventory before attending a special vision clinic. The inventory included 16 questions about visual skills and responses to familiar situations. Responses were augmented by taking a structured clinical history, compared with visual evoked potential (VEP) and/or acuity card measures of visual acuity, and examined using exploratory factor analysis. Acuity ranged from normal to no light perception, and was positively associated with responses to individual questions. After excluding four uninformative questions, an association between the remaining questions and two significant independent factors was found. Factor 1 was associated with questions about visual recognition (e.g. ,Does your child see a small silent toy?') and these items were correlated with both the VEP and acuity card thresholds. Factor 2 was associated primarily with questions about visually mediated social interactions (e.g. ,Does he/she return your silent smile?'). Evaluation of visual skills in children with neurological impairment can provide valid information about the quality of children's vision. Questions with the highest validity for predicting vision are identified. [source] Haphazard neural connections underlie the visual deficits of cats with strabismic or deprivation amblyopiaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Guy Gingras Abstract Identification of the neural basis of the visual deficits experienced by humans with amblyopia, particularly when associated with strabismus (strabismic amblyopia), has proved to be difficult in part because of the inability to observe directly the neural changes at various levels of the human visual pathway. Much of our knowledge has necessarily been obtained on the basis of sophisticated psychophysical studies as well as from electrophysiological explorations on the visual pathways in animal models of amblyopia. This study combines these two approaches to the problem by employing similar psychophysical probes of performance on animal models of two forms of amblyopia (deprivation and strabismic) to those employed earlier on human amblyopes (Hess & Field, 1994, Vis. Res., 34, 13397,13406). The tests explore two competing explanations for the visual deficits, namely an evenly distributed loss of neural connections (undersampling) with the amblyopic eye as opposed to disordered connections with this eye (neural disarray). Unexpectedly, the results in animal models of deprivation amblyopia were not in accord with expectations based upon an even distribution of lost connections with the amblyopic eye. However, the results were similar to those observed in a strabismic amblyopic animal and to strabismic amblyopic humans. We suggest that deprivation amblyopia may be accompanied by an uneven loss of connections that results in effective neural disarray. By contrast, amblyopia associated with strabismus might arise from neural disarray of a different origin such as an alteration of intrinsic cortical connections. [source] Assessing the balance capabilities of people with profound intellectual disabilities who have experienced a fallJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 4 2007L. Hale Abstract Background Although it is common for people with intellectual disability (ID) to fall, the reasons for this have not yet been identified. This pilot study aimed to explore the balance capabilities of a sample of adults with profound ID who had experienced a fall, in order to identify possible reasons for falling and to identify potential tests that could be used to quantify balance capabilities in this population group. Methods The neuromuscular systems and balance capabilities of 20 adults with profound ID were comprehensively assessed with a battery of tests, including computerized posturography. Results Of the 20 participants, 15 described themselves as frequent fallers, and 10 participants reported serious injuries as a result of falling. Formalized assessment of the neuromuscular and balance capabilities proved to be challenging, with many participants unable to comprehend what was required of them in the performance of a number of the tests. All participants were observed to have an abnormal pattern of walking. Nine participants completed posturography testing, the main finding of which was that low motor control composite scores indicated a slowing of motor responses to postural perturbations. Other potential risk factors identified were concurrent medical problems, medication, the context and environment of falling, movement impulsiveness and distractibility, and visual deficits. Conclusion The reason why people with ID frequently fall appears complex and multifactorial. Larger studies are required to verify the potential risk factors identified in this pilot study. Many of the standardized outcome measures commonly used in physiotherapy practice to quantify balance capabilities are not suitable for use in this population group, as participants found it difficult to comprehend what was required of them. Allowing the person to become familiarized with both the test and the tester may help to alleviate this problem. Videotaping and quantifying observations of strategies people use to perform common movements such as walking or turning maybe a more appropriate measurement tool of balance capabilities of people with ID than current standardized measures. This method would require rigorous development. [source] The use of tinted lenses to alleviate reading difficultiesJOURNAL OF RESEARCH IN READING, Issue 1 2001Helen Whiteley An increasing number of optometrists are offering assessments using the Intuitive Colorimeter (Wilkins, Nimmo-Smith and Jansons, 1992) to determine whether children who have reading difficulties might benefit from the use of tinted lenses. Suggestions have been made in the media that tinted lenses may provide a ,cure' for developmental dyslexia, and there have been many anecdotal accounts of improvements in reading following their use (e.g. Brace, 1993). However, such extreme claims are not typical of the scientific literature supporting the use of tinted lenses. This article provides an overview of the research into the use of tinted lenses for the amelioration of reading difficulties. The electronic databases searched for this review were BIDS, MEDLINE, PsychInfo, PsychLit and Science Direct. Key search terms used were coloured (colored) lenses, Irlen lenses, scotopic sensitivity and visual deficits in combination with the term ,reading difficulties'. [source] Pulfrich's phenonenon in a case of optic nerve hypoplasiaOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2008Gordon Heron Introduction:, Optic nerve hypoplasia (ONH) is a congenital deficiency of retinal ganglion cells and their axons that form the optic nerve. This condition is associated with visual deficits ranging from no light perception in severe cases to vision within normal ranges in mild cases of ONH. In mild cases, deficits can be limited to sectoral anomalies in the visual field and normal vision with colour vision anomalies have been reported. We report here a case of mild ONH with visual symptoms relating to Pulfrich phenomenon (PP) occurring spontaneously. Methods:, A 12 year girl presented with typical visual symptoms (bumping into objects when walking, poor object location at tennis) associated with the spontaneous PP. A simple pendulum revealed a perceived anticlockwise ellipse indicative of a left eye defect. This was neutralised by an 85% transmission filter placed before the right eye. The inter-ocular latency difference was calculated to be 0.88 (S.D., 0.55) ms. Results:, Fundus biometry showed an asymmetry in optic nerve size, the left being smaller than the right. Visual fields, anomaloscope and other colour vision tests, and both flash and pattern-reversal stimuli Visually Evoked Potentials showed no difference in visual function between the right and left eyes. Conclusions:, A case of very mild ONH gives inter-ocular normal vision and visual function and yet a subtle inter-ocular delay occurs resulting in visual symptoms associated with PP. These were completely removed with tinted spectacles. [source] Presumed perinatal ischemic stroke: Vascular classification predicts outcomesANNALS OF NEUROLOGY, Issue 4 2008Adam Kirton MD, FRCPC Objective Perinatal stroke commonly causes childhood neurological morbidity. Presumed perinatal ischemic stroke (PPIS) defines children presenting outside a normal perinatal period with chronic, focal infarction on neuroimaging. Infarcts are assumed to represent arterial strokes, but recent evidence suggests the periventricular venous infarction (PVI) of infants born preterm may also occur in utero and present as PPIS. Using the largest published cohort, we aimed to define arterial and PVI PPIS syndromes and their outcomes. Methods A PPIS consecutive cohort was identified (SickKids Children's Stroke Program, 1992,2006). Systematic neuroradiological scoring executed by blinded investigators included previously defined arterial stroke syndromes. PVI criteria included unilateral injury with at least four of the following conditions: (1) focal periventricular encephalomalacia, (2) internal capsule T2 prolongation, (3) cortical and (4) relative basal ganglia sparing, and (5) remote hemorrhage. Arterial and PVI classifications were validated and correlated with neurological outcomes (Pediatric Stroke Outcome Measure). Results In 59 PPISs (64% male), 94% of lesions fell within potential middle cerebral artery territories. Although arterial proximal M1 infarction was most common (n = 19; 35%), venous PVI was second (n = 12; 22%) and accounted for 75% of subcortical injuries. Motor outcomes (mean follow-up, 5.3 years) were predicted by basal ganglia involvement including leg hemiparesis, spasticity, and need for assistive devices (p < 0.01). Nonmotor outcomes were associated with cortical involvement, including cognitive/behavioral outcomes, visual deficits, and epilepsy (p < 0.01). Classification interrater reliability was excellent (correlation coefficients > 0.975). Interpretation Recognizable PPIS patterns predict long-term morbidity and may guide surveillance, therapy, and counseling. PVI is an underrecognized cause of PPIS and congenital hemiplegia. Ann Neurol 2008 [source] Impaired visual search in drivers with Parkinson's diseaseANNALS OF NEUROLOGY, Issue 4 2006Ergun Y. Uc MD Objective To assess the ability for visual search and recognition of roadside targets and safety errors during a landmark and traffic sign identification task in drivers with Parkinson's disease (PD). Methods Seventy-nine drivers with PD and 151neurologically normal older adults underwent a battery of visual, cognitive, and motor tests. The drivers were asked to report sightings of specific landmarks and traffic signs along a four-lane commercial strip during an experimental drive in an instrumented vehicle. Results The drivers with PD identified significantly fewer landmarks and traffic signs, and they committed more at-fault safety errors during the task than control subjects, even after adjusting for baseline errors. Within the PD group, the most important predictors of landmark and traffic sign identification rate were performances on Useful Field of View (visual speed of processing and attention) and Complex Figure Test-Copy (visuospatial abilities). Trail Making Test (B-A), a measure of cognitive flexibility independent of motor function, was the only independent predictor of at-fault safety errors in drivers with PD. Interpretation The cognitive and visual deficits associated with PD resulted in impaired visual search while driving, and the increased cognitive load during this task worsened their driving safety. Ann Neurol 2006 [source] | ||||||||||