A survey on computer vision technology in Camera Based ETA devices

Electronic Travel Aid systems are expected to make impaired persons able to perform their everyday tasks such as finding an object and avoiding obstacles easier. Among ETA devices, Camera Based ETA devices are the new one and with a high potential for helping Visually Impaired Persons. With recent advances in computer science and specially computer vision, Camera Based ETA devices used several computer vision algorithms and techniques such as object recognition and stereo vision in order to help VIP to perform tasks such as reading banknotes, recognizing people and avoiding obstacles. This paper analyses and appraises a number of literatures in this area with focus on stereo vision technique. Finally, after discussing about the methods and techniques used in different literatures, it is concluded that the stereo vision is the best technique for helping VIP in their everyday navigation

Oštećenja vida uslijed diskinetskih poremećaja pokreta očiju u djece s diskinetskom cerebralnom paralizom

Despite the fact that ocular and cerebral visual abnormalities are shown to be very frequent in cerebral palsy (CP), children with CP are underreferred to rehabilitation services for visual impairments. Visual component is, together with the motor disorder, an integral part of the clinical picture of CP and not an associated symptom. Therefore, an accurate detection of visual disorders and visual function not only lead to a complete clinical diagnosis but also to an appropriate intervention plan. Hence, the need for a study aiming specifically to describe all the aspects of visual involvement in the dyskinetic CP. Research goals were aimed at gaining insights into the nature of visual impairments and functional vision of children with dyskinetic CP, determining the nature of connection between visual functions and functional vision, with an emphasis on searching for dyskinetic eye movement disorder for understanding the difficulties in performing visual activities of two children with dyskinetic CP from the Zagreb’s county register of CP, which is part of national C28 RCP-HR-Register of cerebral palsy of Croatia included in Surveillance Cerebral Palsy Europe (SCPE). The data were collected using standardized and non-standardized tests for visual function assessment. Dyskinetic eye movement disorder was tested comparing the tested results of visual functions. Functional vision was tested through the observation of the children’s behavior and through open structured questions addressed to parents. Cerebral visual impairment was examined by a questionnaire for cerebral visual impairment screening. Qualitative research analysis shows which ocular and cerebral visual impairments are present as well as their relation to visual functioning. Moreover, it shows clinical features of dyskinetic eye movement disorder that haven’t been shown present among tested children. Since this is the second research up to this date, testing an eye movement disorder that specifically occurs in dyskinetic CP, its characteristics are further discussed and defined. In contrary to previous study, in a child where highly inefficient visual functioning was shown, the cause goes wider from the abnormal eye motility. It consists of combination of several motor and sensory problems (lacking binocular visual acuity, contrast sensitivity, fixation, voluntary eye movements and oculomotricity). Due to the small sample and findings that are, on account of heterogeneity of dyskinetic CP hard to compare, future research is needed to expand overall knowledge of functional vision and visual functions needed for planning rehabilitation and education management for children with dyskinetic CP.Unatoč činjenici da su okularne i cerebralne vizualne abnormalnosti česte u cerebralnoj paralizi (CP), djeca s CP nedostatno podliježu uslugama rehabilitacije oštećenja vida. Vizualna komponenta je, zajedno s motoričkim poremećajem, sastavni dio kliničke slike CP, a ne samo pridruženi simptom. Točno otkrivanje vizualnog profila djece s CP dovodi do sveobuhvatne kliničke dijagnoze i do odgovarajućeg plana intervencije. Stoga je potrebna studija čiji je cilj opisati sve aspekte vizualne uključenosti u diskinetskom tipu CP. Ciljevi istraživanja bili su usmjereni na stjecanje uvida u prirodu vidnih funkcjia i funkcionalnog vida djece s diskinetskom CP, utvrđivanje prirode povezanosti vizualnih funkcija i funkcionalnog vida, s naglaskom na otkrivanje diskinetskog poremećaja pokreta očiju, kako bi se poboljšalo razumijevanje poteškoća u izvođenju vizualnih aktivnosti dvoje djece s diskinetskom CP iz zagrebačkog županijskog registra CP-a, koji je dio nacionalnog registra C28 RCP-HR cerebralne paralize Hrvatske uključen u Surveillance Cerebral Palsy Europe (SCPE). Podaci su prikupljeni korištenjem standardiziranih i nestandardiziranih testova za procjenu vidnih funkcija. Diskinetski poremećaj pokreta očiju testiran je uspoređujući testirane rezultate vidnih funkcija. Funkcionalni vid testiran je promatranjem dječjeg ponašanja u vizualnim zadacima i kroz otvorena strukturirana pitanja upućena roditeljima. Cerebralno oštećenje vida ispitano je upitnikom za screening na cerebralno oštećenje vida. Kvalitativna analiza podataka pokazuje koja su okularna i cerebralna oštećenja vida prisutna kao i njihov odnos prema funkcionalnom vidu. Budući da je ovo drugo do sada istraživanje ispitivanja diskinetskog poremećaja pokreta očiju koji je karakterističan za diskinetsku CP, opisana su njegova klinička obilježja. Suprotno već objavljenoj studiji, kod djeteta kod kojeg je prikazano vrlo neučinkovito vizualno funkcioniranje, uzrok je širi od abnormalne pokretljivosti oka. Sastoji se od kombinacije nekoliko motoričkih i senzoričkih problema (nedostatna binokularna oštrina vida, kontrastna osjetljivost, fiksacija, voljni pokreti očiju i okulomotorika). Zbog malog uzorka i nalaza koji su zbog heterogenosti diskinetičke CP teško usporedivi, potrebna su buduća istraživanja kako bi se proširilo sveukupno znanje o diskinetskom poremećaju pokreta očiju, funkcionalnom vidu i vizualnim funkcijama potrebnim za planiranje edukacije i rehabilitacije djece s diskinetskom CP

A systematic review on 'Foveal Crowding' in visually impaired children and perceptual learning as a method to reduce Crowding

Contains fulltext : 102577.pdf (publisher's version ) (Open Access)Background - This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy visual scenes. Three specific groups experience more foveal crowding than adults with normal vision (NV): 1) children with NV, 2) visually impaired (VI ) children and adults and 3) children with cerebral visual impairment (CVI). The extent and magnitude of foveal crowding as well as interventions aimed at reducing crowding were investigated in this review. The twofold goal of this review is : [A] to compare foveal crowding in children with NV, VI children and adults and CVI children and [B] to compare interventions to reduce crowding. Methods - Three electronic databases were used to conduct the literature search: PubMed, PsycINFO (Ovid), and Cochrane. Additional studies were identified by contacting experts. Search terms included visual perception, contour interaction, crowding, crowded, and contour interactions. Results - Children with normal vision show an extent of contour interaction over an area 1.5-3x as large as that seen in adults NV. The magnitude of contour interaction normally ranges between 1-2 lines on an acuity chart and this magnitude is even larger when stimuli are arranged in a circular configuration. Adults with congenital nystagmus (CN) show interaction areas that are 2x larger than those seen adults with NV. The magnitude of the crowding effect is also 2x as large in individuals with CN as in individuals with NV. Finally, children with CVI experience a magnitude of the crowding effect that is 3x the size of that experienced by adults with NV. Conclusions - The methodological heterogeneity, the diversity in paradigms used to measure crowding, made it impossible to conduct a meta-analysis. This is the first systematic review to compare crowding ratios and it shows that charts with 50% interoptotype spacing were most sensitive to capture crowding effects. The groups that showed the largest crowding effects were individuals with CN, VI adults with central scotomas and children with CVI. Perceptual Learning seems to be a promising technique to reduce excessive foveal crowding effects.14 p

A Neural Model of Visually Guided Steering, Obstacle Avoidance, and Route Selection

A neural model is developed to explain how humans can approach a goal object on foot while steering around obstacles to avoid collisions in a cluttered environment. The model uses optic flow from a 3D virtual reality environment to determine the position of objects based on motion discontinuities, and computes heading direction, or the direction of self-motion, from global optic flow. The cortical representation of heading interacts with the representations of a goal and obstacles such that the goal acts as an attractor of heading, while obstacles act as repellers. In addition the model maintains fixation on the goal object by generating smooth pursuit eye movements. Eye rotations can distort the optic flow field, complicating heading perception, and the model uses extraretinal signals to correct for this distortion and accurately represent heading. The model explains how motion processing mechanisms in cortical areas MT, MST, and posterior parietal cortex can be used to guide steering. The model quantitatively simulates human psychophysical data about visually-guided steering, obstacle avoidance, and route selection.Air Force Office of Scientific Research (F4960-01-1-0397); National Geospatial-Intelligence Agency (NMA201-01-1-2016); National Science Foundation (SBE-0354378); Office of Naval Research (N00014-01-1-0624

Glare and Ocular Diseases

Glare is the result of veiling luminance from the different light sources we are exposed to in our everyday lives. The luminance from glare can cause problems ranging from the discomfort of our eyes to vision loss. All individuals are affected by glare issues but those problems are intensified in patients living with ocular diseases. Therefore, understanding the effects of glare is applicable to elucidating visual function and pathology. This makes glare testing highly necessary in both clinic and research. However, there are many components involved in glare testing that makes attaining valid results difficult. This is evident in the flaws of current glare devices and the lack of a standardization of measuring glare. Despite the insufficiency of most glare devices, evaluating those weaknesses can potentially lead to a better understanding of glare and glare testing

A Neural Model of Visually Guided Steering, Obstacle Avoidance, and Route Selection

A neural model is developed to explain how humans can approach a goal object on foot while steering around obstacles to avoid collisions in a cluttered environment. The model uses optic flow from a 3D virtual reality environment to determine the position of objects based on motion discotinuities, and computes heading direction, or the direction of self-motion, from global optic flow. The cortical representation of heading interacts with the representations of a goal and obstacles such that the goal acts as an attractor of heading, while obstacles act as repellers. In addition the model maintains fixation on the goal object by generating smooth pursuit eye movements. Eye rotations can distort the optic flow field, complicating heading perception, and the model uses extraretinal signals to correct for this distortion and accurately represent heading. The model explains how motion processing mechanisms in cortical areas MT, MST, and VIP can be used to guide steering. The model quantitatively simulates human psychophysical data about visually-guided steering, obstacle avoidance, and route selection.Air Force Office of Scientific Research (F4960-01-1-0397); National Geospatial-Intelligence Agency (NMA201-01-1-2016); National Science Foundation (NSF SBE-0354378); Office of Naval Research (N00014-01-1-0624

Visual correlates of balance and mobility in older adults: Can visual attention training improve performance?

Falls among older adults is a serious problem facing our aging population. It is estimated that one in every three older adults aged 70+ fall every year; some of these experience multiple falls. Thirty five percent of fallers aged 65 - 70 years experience severe injuries, and this rises to 76% in the 80+ age group. Falls can cause deterioration of health, loss of independence, or even death. The first purpose of this thesis (Experiment 1) was to examine the possible link between balance, mobility, fear of falling, and aspects of vision including binocular vision (BV) status and visual attention, measured with a useful field of view test (UFV) and the Attended Field of View (AFOV). In this cross section study I was interested in measures of vision, which have been less studied or not been considered before, specifically tests of BV and visual attention. These were chosen, as previous research had shown that BV disorders are very common in older adults, and that there is an association between a number of functional tasks and visual attention. Associations with balance and mobility would be a significant finding because BV disorders are often treatable and visual attention is trainable. Balance and mobility were assessed using the One Legged Stance test (OLST), the 5 Meter Walk test (5MWT) and the Sit to Stand test (STST). Fear of falling was measured with the Falls Efficacy Scale-International (FES-I). Visual measures included distance, intermediate and near visual acuity (VA), contrast sensitivity, stereoacuity, BV measurements, UFV and AFOV. Seventy-two adults aged 70 and older took part in the study (mean age 80.3 ± 5.9 years). The results showed that abnormal BV, poor intermediate VA and errors on the UFV were all significant predictors of reduced performance in mobility and balance. Univariate regression showed that reduced performance on the OLST and the STST was significantly correlated with abnormal BV and intermediate VA. The 5MWT and the FES-I were also predicted by poor intermediate VA. In addition, the OLST, STST and the 5MWT were all associated with the UFV errors. Multiple regression models included the following: OLST performance was related to BV and eye movement disorders, stereoacuity and UFV errors, STST was related to intermediate VA and 5MWT was related to distance VA. The association between balance and visual attention led me to hypothesize that training visual attention may improve balance and thereby reduce falls. Falls prevention programs typically include vision, exercise, environment modification, education intervention or a combination of these interventions grouped together. The most effective programs may be those that have a multifactorial approach. However, the impact of visual attention training aimed at improving balance and/or mobility has not yet been studied. Therefore, the second purpose of this thesis (Experiment 2) was to investigation of whether visual attention training can improve balance and/or mobility in older adults, with the goal that this may transfer to reducing falls. Experiment 2 was a randomized controlled trial (RCT) in which 15 participants were randomly assigned to a visual attention training group and 15 to a control group. Visual attention training was undertaken with versions of a selective attention useful field of view test (UFV) and attended field of view (AFOV) test. The training sessions were 45 minutes duration, undertaken twice a week for three weeks. The outcome measures were sway using a force plate platform (AMTI AccuGAIT; 200 Hz), the mini Balance Evaluation Systems Test (mini-BESTest), the One Legged Stance test (OLST), the 5 Meter Walk test (5MWT), the Sit to Stand test (STST), the Timed Up and Go test without (TUG) and with a concurrent cognitive task (TUGco). It was found that visual attention significantly improved after training (p0.05 in all cases) in eyes open and eyes closed conditions. A mixed ANOVA (2x group, 2x visits) of the changes over time for the other balance and mobility assessment tools also showed no improvement after the visual attention training (Mini-BESTest, p=0.25: 5MWT, p=0.28: OLST, p=0.31: STST, p=0.029: TUG, p=0.08: TUGco, p=0.21). To conclude, a variety of measures of visual function were shown to be related to poor performance in balance and mobility tasks. Poor BV, distance and intermediate VA and visual attention were among these measures. It is important that eye care practitioners who work with older adults be aware of these associations, question older adults about a history of falls or walking and balance problems, and ensure that the vision of older people is optimally managed. Although visual attention itself was improved by the training, there was no improvement in either mobility or balance and no difference between the intervention and the control groups post visual attention training. It was concluded that UFV and AFOV visual attention training alone is not effective to improve balance and mobility; a training program that includes movement and visual attention may be needed to obtain improvement in balance and mobility. Since a substantial portion of the older adult population fall every year the results of this study are important as it supports the notion that a multi-component approach is still the recommended route to reduce the risk of falls

Vision Development Differences between Slow and Fast Motor Development in Typical Developing Toddlers: A Cross-Sectional Study

Many studies have established a relationship between visual function and motor development in toddlers. This is the first report to study two-year-olds via an assessment of their visual and motor skills. The purpose of this study is to describe the possible changes that can occur between visual and motor systems in typical developing toddlers. A total of 116 toddlers were included in this observational, descriptive, and cross-sectional study. Their mean age was 29.57 +/- 3.45 months. Motor development variables studied were dominant hand/foot; stationary, locomotion, object manipulation, grasping, visual motor integration percentiles; gross motor, fine motor, and total motor percentiles; and gross motor, fine motor, and total motor quotients. Visual development variables were assessed including visual acuity, refractive error, ocular alignment, motor fusion and suppression, ocular motility, and stereopsis. Our findings demonstrated that typical developing toddlers with slow gross motor development had higher exophoria and further near point of convergence values compared to toddlers with fast gross motor development (p < 0.05). No statistically significant differences were found in visual acuity and stereopsis between slow and fast gross motor development toddlers

Explaining Self-Motion Perception using Virtual Reality in Patients with Ocular Disease

Safe mobility requires accurate object and self-motion perception. This involves processing retinal motion generated by optic flow (which change with eye and head movements) and correctly integrating this with vestibular and proprioceptive cues. Poor sensory feedback of self-motion can lead to increased risks of accidents which impacts quality of life. This is further problematic for those with visual deficits, such as central or peripheral vision loss or impaired binocular vision. The expansion of healthcare into using virtual reality (VR) has allowed the assessment of sensory and motor performance in a safe environment. An advantage of VR is its ability to generate vection (perceived illusory self-motion) and presence (sense of being ‘there’). However, a limitation is the potential to develop cybersickness. Initially, the project examined how binocular vision influences vection in a virtual environment. Observers with or without stereopsis (ability to judge depth binocularly) were asked to compare their perceptual experiences based on psychophysical judgements of magnitude estimation. The findings suggest that the absence of stereopsis impairs accurate judgement of self-motion and reduces perceived presence, however, it was protective for cybersickness. The project then examined the impact of central and peripheral vision loss on self-motion perception by comparing those with age-related macular degeneration (AMD) and glaucoma respectively. Effects of these visual deficits on sensory conflicts involving visual-vestibular interactions was then assessed. Sensory conflict was imposed by altering the gain of simulated head linear head position and angular orientation to be either compatible or incompatible with head movement in two separate experiments. Fixation was used to control gaze during changes in angular head orientation. Vection and presence was higher in those with AMD, compared with those with glaucoma, indicating the importance of regional specificity in visual deficits on self-motion perception. Across studies, vection and presence were predominantly visually mediated despite changes in visual-vestibular sensory conflict. The vestibular system, however, appeared to play a larger role in developing cybersickness. The altered perception of self-motion may worsen mobility, particularly with disease progression. We therefore provide a framework and recommendations for a multidisciplinary patient-centric model of care to maximise quality of life