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Access to culturally safe health services is a basic human right, however through the lasting effects of colonisation, oppression, and systemic racism, the individual and community health of Indigenous peoples in Australia and Aotearoa New Zealand have been severely impacted. The Aboriginal and Torres Strait Islander Health and Cultural Safety Strategy of the Australian Health Practitioners Regulation Agency, and the Standards of Cultural Competence and Cultural Safety of the Optometrists and Dispensing Opticians Board of New Zealand, recognise the importance of access to safe health care for Aboriginal, Torres Strait Islander and Māori patients, which encompasses both clinical competency and cultural safety. Universities have an ongoing responsibility to ensure their learning and teaching activities result in graduates being able to provide culturally safe practice. This article highlights the emergence of culturally safe practices in the Australian and Aotearoa New Zealand optometry curricula over the last five years incorporating Indigenous ways of knowing, being and doing into the curricula, understanding the local Indigenous histories and contexts, the adoption of online cultural education modules, and clinical placement partnerships with local Indigenous communities. Whilst there is still much work to do to achieve the goal of graduating culturally safe optometrists, this paper focuses on features that enable or impede progress in the development of culturally safe practices within the optometry programmes to improve eye health equity for Indigenous recognise the diversity of Indigenous cultures across Australia and NZ.

Appropriately skilled staff are required to meet the health and care needs of aging populations yet, shared competencies for the workforce are lacking. This study aimed to develop multidisciplinary core competencies for health and aged care workers in Australia through a scoping review and Delphi survey. The scoping review identified 28 records which were synthesized through thematic analysis into draft domains and measurable competencies. Consensus was sought from experts over two Delphi rounds (n = 111 invited; n = 59 round one; n = 42 round two). Ten domains with 66 core competencies, to be interpreted and applied according to the worker's scope of practice were finalized. Consensus on multidisciplinary core competencies which are inclusive of a broad range of registered health professionals and unregistered aged care workers was achieved. Shared knowledge, attitudes, and skills across the workforce may improve the standard and coordination of person-centered, integrated care for older Australians from diverse backgrounds.

BACKGROUND Convergence insufficiency may be treated by visual exercises designed to increase convergence while maintaining single, clear, binocular vision. However, compliance with treatment is problematic, as patients often cease treatment when symptoms start to improve and before treatment is complete. The purpose of the present study was to assess the feasibility of using gamification of vision training to: (a) treat convergence insufficiency; and (b) improve compliance to treatment in comparison to a conventional treatment over a six-week treatment period. METHODS Two interventions, anaglyphs and a virtual reality game of Snakes, were evaluated for their effectiveness in treating adults with convergence insufficiency. The prescribed training regimen was 20 minutes, three times per week for six weeks. Vision was assessed before and after the treatment period. Participants also filled in the Core Elements of the Gaming Experience Questionnaire to gauge impact of game design on compliance. RESULTS Eighteen participants (mean age 20.8 ± 1.8 years) met the inclusion criteria for convergence insufficiency and nine participants were randomly assigned to each intervention. Repeated measures analysis of variance showed a significant effect of visit for near point of convergence (F1,16 = 38.32, p

PURPOSE: An orientation-specific visual evoked potential (osVEP) protocol was developed to probe meridional anisotropies in children with refractive amblyopia. The aim was to characterise the osVEP response in children with bilateral refractive amblyopia, evaluate the intra-session repeatability of the main osVEP components (C1, C2 and C3), coefficient of repeatability (CoR) of the response to gratings in different meridians and determine if refractive amblyopes have poorer repeatability as compared with non-amblyopic controls.\ud \ud METHODS: Children aged 4-7 years with newly diagnosed and untreated bilateral refractive amblyopia and non-amblyopic controls were recruited. Orientation-specific pattern-onset VEPs were recorded in response to an achromatic sinewave grating stimulus of 4 cycles per degree under monocular and binocular stimulation. The grating lines used for monocular stimulation were parallel with the subjects' most positive and negative astigmatic meridians when considered in sphero-minus cylinder form (Meridians 1 and 2, respectively). In subjects without astigmatism, meridians 1 and 2 were designated horizontal and vertical gratings, respectively. Binocular stimuli were presented with grating lines parallel to meridians 45, 90, 135 and 180°. The repeatability of latencies of the main osVEP components (C1, C2 and C3) were investigated using two successive osVEPs recordings for each stimulus meridian and the CoR for each component's latencies were assessed.\ud \ud RESULTS: Seven amblyopic children (Visual acuity (VA) ranging from 0.08 to 0.40 LogMAR in the less amblyopic eye and 0.26-0.52 LogMAR in the more amblyopic eye) and 7 non-amblyopic controls (VA ranging from 0.00 to 0.02 LogMAR in either eye), with a median age of 4.6 and 7.0 years, respectively, completed the study. C1 had the highest CoR for most conditions assessed. Ratio of CoRs C1:C2 was > 2 for all binocular meridians in controls and the 90 and 180 meridians in the amblyopes; C1:C3 was > 2 for the binocularly assessed 45, 90 and 135 meridians in the controls and the 90 and 180 meridians in the amblyopes; C2:C3 were all

BACKGROUND: Standards writers, national and international, have used different contrast calculations to set requirements in building elements for people with visual impairments. On the other hand, they have typically set a single requirement (30%) for specifying the minimum contrast. The systems are not linearly related and 30% means something rather different in each system. OBJECTIVE: To provide a comparison of the various scales in order to illustrate the differences caused by multiple scales with a single compliance value, recommend a single scale for universal adoption and, if a new measure is problematic for implementation, to recommend the most perceptually uniform of the present methods. METHODS: We use the contrast between combinations of 205 paint colours to illustrate the relationships between the measures. We use an internationally accepted scale, with equal perceptual steps, as a “gold standard” to identify the most perceptually uniform measurement scale in the existing methods. RESULTS: We show that Michelson contrast is the most perceptually uniform of the existing measurement scales. We show the contrasts in the proposed method that equate to the various current requirements. CONCLUSIONS: We propose that CIE Metric Lightness could be used as the contrast measure. Alternatively, Michelson contrast is the most perceptually linear of the current measurement scales.

Patients should be able to rely on optometrists and optical dispensers to provide evidence-based answers to their questions on eye protection, including against ultraviolet radiation. Surveys indicate that there is public concern about the need for protection against ultraviolet radiation, particularly in sunlight. This investigation aimed to evaluate the quality of information provided by practitioners in response to typical questions to which they might reasonably be expected to have ready answers. A cross-sectional study was conducted of on-site responses from attendees of a 3 day optical fair, in Sydney, Australia, in 2017. Subjects were not forewarned about the study. The portion of the questionnaire reported here comprised open answers to four questions intended to represent typical enquiries of patients. The questions were about recommendations for ultraviolet protection in the context of 1) computer use, 2) outdoor use, 3) driving and 4) under office lighting. Eighty-three participants returned completed questionnaires out of 140 issued (61% response). The open-answer question responses were grouped into appropriate, borderline (mostly appropriate but mixed with non-UVR related recommendations) and others (mostly non-UVR related recommendations) and by job title. The proportion of appropriate answers to the four questions were 20%, 30%, 12% and 15%, respectively, which did not differ by job title. A significantly higher proportion of optical dispensers than optometrists selected 'Don't know/no answer' for all questions except office use. Eyecare professionals need to be educated on eye protection against UV radiation to improve the quality of information to be given to the public.

Australia is one of only two known countries with a safety standard specifying levels of contrast required to provide accessible environments for people with visual impairment. However, these requirements were not developed based on empirical research involving people with vision loss. We investigated whether the level of luminance contrast in Australian accessibility standards, 30%, is adequate for people with visual impairments to detect and identify discrete tactile ground surface indicators over a range of contrasts with the background flooring before contact. We found that the 30% luminance contrast is adequate for people with low vision, although they preferred higher contrast.

The qualities of the built environment impact on the ability of people with vision impairment to move safely through the environment. It is important to revisit the evidence of the relationship between vision and the visibility of elements in the built environment to ensure accessibility standards and design guidelines are consistent with the latest evidence base. This paper reviews mixed method (qualitative and quantitative) research into visual and non-visual factors known to be implicated in injurious incidents in people with vision impairment. The evidence base for the visibility of simulated and real environmental elements such as stairs, doors, door handles, light switches, tactile ground surface indicators, traffic cones, road line markings and pedestrians will be reviewed. The evidence suggests that luminance contrasts of approximately 2.5× current contrast standards, as current standards vary, would allow people with up to severe vision impairment to see objects of the dimensions of tactile ground surface indicators with ease. If people who are categorised as being blind by WHO are considered, about 3× current contrast standards may be required. If lower contrasts are used, alternative provisions should be made to assist people with vision impairment to navigate the space safely.

Tinted lenses may adversely affect colour discrimination. Before recommending tinted lenses to patients, practitioners should bear in mind any effects on colour discrimination. The effects of ‘blue‐blocking’ spectacle lenses with high luminous transmittance on colour vision is not a concern. Blue‐blocking lenses have been widely promoted by manufacturers and practitioners. The more blue‐blocking lenses are known to affect colour vision significantly but there has been no study of the effects of ‘blue‐blocking’ spectacle lenses. The transmittances of commercially available lenses were measured and the three lenses with the lowest blue light transmittance were selected. Subjects undertook the following computer‐based colour vision tests: Colour Assessment and Diagnosis; the Cambridge Colour Test; and the Farnsworth‐Munsell 100 Hue Test. Blue and luminous transmittances of lenses were documented. The reduction in blue transmittance varied from 12 to 40 per cent (two to 30 per cent compared with an untinted lens). The lenses were found to have no significant, statistical or possibly practical, effect on the results of the three colour vision tests (t‐test, analysis of variance, Mann–Whitney, Kruskal‐Wallis). The modest blue light transmittance reduction of the ‘blue‐blocking’ spectacle lenses examined was not sufficient to have a statistically significant effect on colour vision.

An orientation-specific visual evoked potential (osVEP) protocol was developed to probe meridional anisotropies in children with refractive amblyopia. The aim was to characterise the osVEP response in children with bilateral refractive amblyopia, evaluate the intra-session repeatability of the main osVEP components (C1, C2 and C3), coefficient of repeatability (CoR) of the response to gratings in different meridians and determine if refractive amblyopes have poorer repeatability as compared with non-amblyopic controls.Children aged 4-7 years with newly diagnosed and untreated bilateral refractive amblyopia and non-amblyopic controls were recruited. Orientation-specific pattern-onset VEPs were recorded in response to an achromatic sinewave grating stimulus of 4 cycles per degree under monocular and binocular stimulation. The grating lines used for monocular stimulation were parallel with the subjects' most positive and negative astigmatic meridians when considered in sphero-minus cylinder form (Meridians 1 and 2, respectively). In subjects without astigmatism, meridians 1 and 2 were designated horizontal and vertical gratings, respectively. Binocular stimuli were presented with grating lines parallel to meridians 45, 90, 135 and 180°. The repeatability of latencies of the main osVEP components (C1, C2 and C3) were investigated using two successive osVEPs recordings for each stimulus meridian and the CoR for each component's latencies were assessed.Seven amblyopic children (Visual acuity (VA) ranging from 0.08 to 0.40 LogMAR in the less amblyopic eye and 0.26-0.52 LogMAR in the more amblyopic eye) and 7 non-amblyopic controls (VA ranging from 0.00 to 0.02 LogMAR in either eye), with a median age of 4.6 and 7.0 years, respectively, completed the study. C1 had the highest CoR for most conditions assessed. Ratio of CoRs C1:C2 was 2 for all binocular meridians in controls and the 90 and 180 meridians in the amblyopes; C1:C3 was 2 for the binocularly assessed 45, 90 and 135 meridians in the controls and the 90 and 180 meridians in the amblyopes; C2:C3 were all 2 for all meridians assessed in both groups.The osVEP waveforms are reliable and useful for future investigations into the meridional anisotropies in children with refractive amblyopia, particularly the C3 component. Component C1 had the poorest repeatability, which consequentially affected C2 amplitude estimation. Only C3 amplitude and latency could be consistently estimated as C2 and C3 latencies were similarly repeatable. Coefficients of repeatability of osVEP latencies did not appear to systematically differ between non-amblyopic and amblyopic children.

Tablet computer displays are amenable for the development of vision tests in a portable form. Assessing color vision using an easily accessible and portable test may help in the self-monitoring of vision-related changes in ocular/systemic conditions and assist in the early detection of disease processes. Tablet computer-based games were developed with different levels of gamification as a more portable option to assess chromatic contrast sensitivity. Game 1 was designed as a clinical version with no gaming elements. Game 2 was a gamified version of game 1 (added fun elements: feedback, scores, and sounds) and game 3 was a complete game with vision task nested within. The current study aimed to determine the normative values and evaluate repeatability of the tablet computer-based games in comparison with an established test, the Cambridge Colour Test (CCT) Trivector test. Normally sighted individuals [N = 100, median (range) age 19.0 years (18-56 years)] had their chromatic contrast sensitivity evaluated binocularly using the three games and the CCT. Games 1 and 2 and the CCT showed similar absolute thresholds and tolerance intervals, and game 3 had significantly lower values than games 1, 2, and the CCT, due to visual task differences. With the exception of game 3 for blue-yellow, the CCT and tablet computer-based games showed similar repeatability with comparable 95% limits of agreement. The custom-designed games are portable, rapid, and may find application in routine clinical practice, especially for testing younger populations.

Purpose: We investigated the pattern of meridional anisotropies, if any, for pattern onset-offset visual evoked potential (POVEPs) responses and psychophysical grating acuity (GA) in children with normal letter visual acuity (20/20 or better). \ud \ud Methods: A total of 29 children (aged 3-9 years), nine of whom were astigmatic (AS), were recruited. Orientation-specific monocular POVEPs were recorded in response to sinewave grating stimuli oriented along the subjects' principal AS meridians. Horizontal and vertical gratings were designated Meridians 1 and 2, respectively, for nonastigmatic patients (Non-AS). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed monocularly and binocularly along the same meridians using the same stimuli by a 2-alternative-forced-choice staircase technique. The C3 amplitudes and peak latencies of the POVEP and GAs were compared across meridians using linear mixed models (monocular) and ANOVA (binocular). \ud \ud Results: There were significant meridional anisotropies in monocular C3 amplitudes regardless of astigmatism status (P = 0.001): Meridian 2 (mean ± SE Non-AS, 30.13 ± 2.07 μV; AS, 26.53 ± 2.98 μV) was significantly higher than Meridian 1 (Non-AS, 26.14 ± 1.87 μV; AS, 21.68 ± 2.73 μV; P = 0.019), but no meridional anisotropies were found for GA or C3 latency. Binocular C3 amplitude in response to horizontally oriented stimuli (180°, 29.71 ± 3.06 μV) was significantly lower than the oblique (45°, 36.62 ± 3 .05 μV; P = 0.03 and 135°, 35.95 ± 2.92 μV; P = 0.04) and vertical (90°, 37.82 ± 3.65 μV; P = 0.02) meridians, and binocular C3 latency was significantly shorter in response to vertical than oblique gratings (P ≤ 0.001). \ud \ud Conclusions: Meridional anisotropy was observed in children with normal vision. The findings suggest that horizontal gratings result in a small, but significantly lower POVEP amplitude than for vertical and oblique gratings.

Despite orientation and mobility (O&M) being a significant factor determining quality of life of people with low vision or blindness, there are no gold standard measures or agreement on how to measure O&M performance. In the first part of this systematic review, an inventory of O&M outcome measures used by recent studies to assess the performance of orientation and/or mobility of adults with vision impairment (low vision and blindness) is presented. A wide variety of O&M outcome measures have been implemented in different fields of study, such as epidemiologic research and interventional studies evaluating training, assistive technology, vision rehabilitation and vision restoration. The most frequent aspect of outcome measures is efficiency such as time, distance, speed and percentage of preferred walking speed, followed by obstacle contacts and avoidance, and dis/orientation and veering. Other less commonly used aspects are target identification, safety and social interaction and self-reported outcome measures. Some studies employ sophisticated equipment to capture and analyse O&M performance in a laboratory setting, while others carry out their assessment in real-world indoor or outdoor environments. In the second part of this review, the appropriateness of implementing the identified outcome measures to assess O&M performance in clinical and functional O&M practice is evaluated. Nearly a half of these outcome measures meet all four criteria of face validity (either clinical or functional), responsiveness, reliability and feasibility and have the potential to be implemented in clinical or functional O&M practice. The findings of this review confirm the complicated and dynamic nature of O&M. Multiple measures are required in any evaluation of O&M performance to facilitate holistic assessment of O&M abilities and limitations of each individual.

Byoung Sun Chu,1 Mei Ying Boon,2 Dong Hwan Noh3 1School of Optometry and Vision Science, Daegu Catholic University, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do, Republic of Korea; 2School of Optometry and Vision Science, University of New South Wales, Sydney, Australia; 3DAVICH Optical Chain, Daechi-dong, Gangnam-gu, Seoul, South Korea Background: The purpose of this study is to investigate and compare spectacle and contact lens (CL) prescription trends, with an emphasis on astigmatic refractive error prescribing differences for patients who purchase spectacles or CLs in South Korea.Methods: A retrospective study of patient records of a major optical chain in South Korea was conducted. De-identified data of age, gender, power of prescribed spectacles and/or CLs were extracted from the practice database. Inclusion criteria were being within the first 10,000 purchasers of spectacles or CLs or both.Results: The first 10,000 purchases comprised spectacles (59%) and CLs (41%) (male:female ratio 4:6). The proportion of purchasers who were female was significantly higher for CLs (88% female, 12% male) than spectacles (43% female, 57% male) (χ2=4480.36, df=1, P

Background: Eye-care practitioners are often required to make recommendations regarding their patients' visual fitness for driving, including patients with visual impairment. This study aimed to understand the perspectives and management strategies adopted by optometrists regarding driving for their patients with central visual impairment. Method: Optometrists were invited to participate in an online survey (from April to June 2012). Items were designed to explore the views and practices adopted by optometrists regarding driving for patients with central visual impairment (visual acuity [VA] poorer than 6/12, normal visual fields, cognitive and physical health), including conditional driver's licences and bioptic telescopes. Closed- and open-ended questions were used. Results: The response rate was 14 per cent (n = 300 valid responses were received). Most respondents (83 per cent) reported that they advised their patients with visual impairment to ‘always’ or ‘sometimes’ stop driving. Most were confident in interpreting the visual licensing standards (78 per cent) and advising on legal responsibilities concerning driving (99 per cent). Respondents were familiar with VA requirements for unconditional licensing (98 per cent); however, the median response VA of 6/15 as the poorest VA suggested for conditional licences differed from international practice and Australian medical guidelines released a month prior to the survey's launch. Few respondents reported prescribing bioptic telescopes (two per cent). While 97 per cent of respondents stated that they discussed conditional licences with their patients with visual impairment, relatively few (28 per cent) reported having completed conditional licence applications for such individuals in the previous year. Those who had completed applications were more experienced in years of practice (p = 0.02) and spent more time practising in rural locations (p = 0.03) than those who had not. Conclusion: The majority of Australian optometrists were receptive to the possibilities of driving options for individuals with central visual impairment, although management approaches varied with respect to conditional licensing.

Purpose: We investigated and characterized the patterns of meridional anisotropies in newly diagnosed refractive amblyopes using pattern onset–offset visual evoked potentials (POVEPs) and psychophysical grating acuity (GA).\ud \ud Methods: Twenty-five refractive amblyopes were recruited and compared with non-amblyopic controls from our previous study. Monocular POVEPs were recorded in response to sinewave 4 cycles per degree (cpd) grating stimuli oriented along each individual participants' principal astigmatic meridians, which were approximately horizontal (meridian 1) and vertical (meridian 2). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed along the same meridians using a two-alternative non-forced-choice technique. The C3 amplitudes and peak latencies of the POVEPs and GAs were compared across meridians for both groups (refractive amblyopes and controls) using linear mixed models (monocular) and ANOVA (binocular), and post hoc analysis was conducted to determine if meridional anisotropies in this cohort of amblyopes were related to low (≤1.50 diopters [D]), moderate (1.75–2.75 D) and high (≥3.00 D) astigmatism.\ud \ud Results: In the newly diagnosed refractive amblyopes, there were no significant meridional anisotropies across all outcome measures, but the post hoc analysis demonstrated that C3 amplitude was significantly higher in those with low (P = 0.02) and moderate (P = 0.004) astigmatism compared to those with high astigmatism. Refractive amblyopes had poorer GA and C3 amplitudes compared to controls by approximately two lines on the logMAR chart (monocular: P = 0.013; binocular: P = 0.014) and approximately 6 µV (monocular: P = 0.009; binocular: P = 0.027), respectively.\ud \ud Conclusions: Deleterious effects of high astigmatism was evident in newly diagnosed refractive amblyopes, but the neural deficits do not seem to be orientation-specific for the stimulus parameters investigated.

Lighting conditions nominated for color vision testing are many and varied. The recommendation of CIE color rendering index (CIE CRI) ≥ 90 and correlated color temperature of close to 6500 K is widely made for color vision testing generally. With the demise of incandescent and fluorescent lighting and their replacement by light-emitting diodes (LEDs), this is an opportune time to revisit the recommendation. In this paper, we consider the current sources, acceptable and unacceptable, and improvements to the recommendation as it applies to the Farnsworth–Munsell 100 Hue Test (FM100Hue Test). We conclude that there is no need to treat LEDs as a special case but propose a modified CRI measure.

Visual impairment (VI) can result from many different ocular diseases and is defined as the poor functioning of the visual system. To describe the extent of VI, clinical measures of visual function are used, which include visual acuity (VA), visual field (VF) and contrast sensitivity (CS). When there is a reduction in any of these visual functions, safe and efficient mobility is one such activity that may be compromised. While there is currently no cure for VI-causing retinal diseases such as retinitis pigmentosa (RP), age-related macular degeneration (AMD) and glaucoma, gene therapy is gaining traction as a possible treatment. Preliminary results have shown that patients have performed significantly better on mobility tasks, such as the navigation of an obstacle course, post-treatment. Interestingly, visual function measures have not always shown such significant improvement. It is therefore important to develop a standardized obstacle course that can assess therapy efficacy, as the drawbacks of current physical orientation and mobility obstacle courses include high cost of set-up, potential dangers to participants and the fact that performance may reflect non-visual abilities such as physical fitness. To address these concerns, we have investigated the use of a virtual obstacle course in people with visual impairment. Here we report the initial behaviors and strategies of people with visual impairment as they navigate through four obstacle tasks using a virtual reality headset.

Background: Vergence eye movements are the disconjugate movements of the two eyes, needed to accurately ‘point’ the eyes at an object of interest. Convergence insufficiency is the reduced ability to elicit and maintain the eyes in the accurate convergence position, and it affects about 5% of the population, often leading to visual symptoms such as diplopia (double vision), eye strain and headaches, especially during near tasks. The ability to converge and diverge accurately can be trained with vision training, but vision training activities are not standardized and they are often not complied with. Methods: We developed a novel virtual reality (VR) snake game and compared it with conventional anaglyph treatments in a randomized controlled trial on typical adults. Compliance was assessed by the time spent doing the prescribed vision training over a period of three weeks. Results: There was a statistically significant improvement of convergence ability in both the VR snake and anaglyph treatment groups, and no difference in compliance between the two groups. Conclusion: Virtual reality headsets may be used to train vergences in adults. Further work is required to determine its utility in people with convergence insufficiency who require training for longer than 3 weeks.

Gamification has been incorporated into vision tests and vision therapies in the expectation that it may increase the user experience and engagement with the task. The current study aimed to understand how gamification affects the user experience, specifically during the undertaking of psychophysical tasks designed to estimate vision thresholds (chromatic and achromatic contrast sensitivity).Three tablet computer-based games were developed with three levels of gaming elements. Game 1 was designed to be a simple clinical test (no gaming elements), game 2 was similar to game 1 but with added gaming elements (i.e., feedback, scores, and sounds), and game 3 was a complete game. Participants (N = 144, age: 9.9-42 years) played three games in random order. The user experience for each game was assessed using a Short Feedback Questionnaire.The median (interquartile range) fun level for the three games was 2.5 (1.6), 3.9 (1.7), and 2.5 (2.8), respectively. Overall, participants reported greater fun level and higher preparedness to play the game again for game 2 than games 1 and 3 (P 0.05). There were significant positive correlations observed between fun level and preparedness to play the game again for all the games (p 0.05). Engagement (assessed as completion rates) did not differ between the games.Gamified version (game 2) was preferred to the other two versions. Over the short term, the careful application of gaming elements to vision tests was found to increase the fun level of users, without affecting engagement with the vision test.

Background This study investigated the referral pathways offered to patients with age-related macular degeneration (AMD), diabetic retinopathy (DR) or glaucoma (GL) by ophthalmologists and optometrists. Methods Australian ophthalmologists and optometrists were surveyed regarding referral decisions to other eye-care specialists (inter- or intra-professional), general medical practitioners (GPs), low vision rehabilitation (LVR) and support services. Thematic analysis and concept mapping were applied to highlight current and ideal referral pathways. Results The survey was completed by 155 optometrists and 50 ophthalmologists and deemed representative of their respective professions in Australia. Not surprisingly, the vast majority of the participating optometrists (97 to 99 per cent) referred to ophthalmologists regardless of the underlying condition. Clear differences (Chi-square: p

Purpose To investigate the age range for which cycloplegia provides additional information compared with non-cycloplegic refraction in teenagers and young adults. Methods Data for 1295 subjects (704 female; 591 male) from the Twins Eye Study in Tasmania (TEST) and the Brisbane Adolescent Twin Study (mean age: 19.65 ± 3.56, range: 13–26 years) were included. For all participants, cycloplegia was induced by instillation of either one drop of 1% cyclopentolate (13–14 years) or one drop of 1% tropicamide (15–26 years). Pre- and postcycloplegic refractive errors for both eyes were measured using a Humphrey-598 automated refractor and spherical equivalents of refractive error were calculated. Generalized Estimating Equations (GEE) were used to model the spherical equivalent refraction (SER) for each eye against age (by year) and axial length (in the given eye). Results The mean group difference between pre- and postcycloplegic SER (post minus pre) was 0.17 ± 0.52 D and 0.12 ± 0.51 D for the right and left eyes, respectively, indicating that postcycloplegic refraction was generally more hyperopic/less myopic. The mean difference between pre- and postcycloplegic SER decreased from 0.36 ± 0.41 D in the 13-year-olds to 0.06 ± 0.50 D in people aged 25 years. After adjusting for family-relatedness, the difference between pre- and postcycloplegia SER was significant in all age groups up until the age of 20 years. Conclusions Non-cycloplegic autorefraction can result in group mean SER differences of greater myopia than cycloplegic autorefraction and occurs in teenagers (13–19 years of age), but not in adults 20–26 years. These data suggest that cycloplegia is not required in population estimates of refractive error for young adults once they reach approximately 20 years of age.

Background The aim was to obtain an overview of general medical practitioner (GP) referral pathways to ocular health care and allied services for people identified with age-related macular degeneration (AMD), diabetic retinopathy (DR) or glaucoma (GL). Methods A questionnaire was developed to survey GPs in Australia. Questions included demographic information and referral patterns to ocular and health service providers. The survey was posted to 1,050 randomly selected GPs across Australia. Results Fifty-eight GPs participated in this study amounting to a 6.5 per cent response rate. Nearly all GPs referred patients to ophthalmologists (AMD: 98 per cent; DR: 98 per cent; GL: 95 per cent). A smaller proportion of GPs also referred to low vision rehabilitation (LVR) services (AMD: 34 per cent; DR: 33 per cent; GL: 22 per cent), optometrists (AMD: 26 per cent; DR: 34 per cent; GL: 31 per cent), or support services (AMD: 17 per cent; DR: 40 per cent; GL: 19 per cent). For the three tested conditions, there were no statistically significant differences in the proportions of GPs, who referred to ophthalmologists (p = 0.43), optometrists (p = 0.48) or to low vision rehabilitation services (p = 0.31). The proportion of GPs who referred to support services was significantly higher for patients diagnosed with DR than AMD or GL (p < 0.05). Conclusion The majority of GPs referred patients with AMD, DR or GL to ophthalmologists. Fewer GPs considered referrals to optometrists, low vision rehabilitation or support services. General practitioners may need to be more aware about the central role of optometrists in the delivery of primary eye health care. In the interest of optimising eye care, closer working relationships between GPs and optometrists should be fostered.

BACKGROUND People with low vision complain of difficulty operating controls on electronic appliances and equipment which suggests that the readability of controls and their labels is below their ability. OBJECTIVE To investigate whether electronic appliances available today are designed with controls of sufficient size (at least 6/18 Snellen VA) and contrast (at least 30%) to facilitate identification and use by people with low vision. METHODS Controls and labels of electronic appliances for sale in retail stores in Singapore (January, February 2012) and a sample of domestic appliances in Sydney, Australia (October, November of 2011) were evaluated in terms of high- and low- importance in function, size and contrast (luminance and colour difference). RESULTS Labels and controls of 96 electronic appliances were evaluated. All controls were of sufficient size but 22% (26/117) of high- and 27% (12/44) of low-importance controls measured had insufficient luminance contrast. 79% (152/192) of high- and 46% (24/52) of low-importance labels were of insufficient size. 17% (26/160) of the high- and 0.03% (1/33) of low-importance labels had insufficient luminance contrast. CONCLUSIONS Most controls and labels of recently available electronic appliances can cause problems for operability in people with low vision.

The aim was to develop and validate an instrument called the 'Children's Vision for Living Scale' (CVLS) for the assessment of vision-related quality of life in Saudi Arabian children with and without amblyopia.A 43-item child self-report questionnaire was initially developed based on interviews with children with amblyopia, their parents and eye-care professionals, and a literature review. Following a process that involved the removal of redundant items, 28 items remained and were piloted on children aged five to 12 years with and without amblyopia (n = 48 amblyopic, n = 53 non-amblyopic) living in Saudi Arabia. Rasch analysis was applied to determine whether the 28-item questionnaire fitted the Rasch model. Rasch analysis was used to assess the validity and reliability of the questionnaire. Principal components analysis (PCA) was used to check dimensionality. A 21-item questionnaire resulting from this process was administered in children with (n = 81) and without (n = 82) amblyopia in Saudi Arabia for further validation.The final 21-item questionnaire had good validity and reliability as demonstrated by person separation of 2.02, person reliability of 0.80 (mean square and standard deviation: infit = 1.01 ± 0.39; outfit = 1.01 ± 0.40) and item reliability of 0.93 (item infit range = 1.33 to 0.78; item outfit range = 0.78 to 1.30). The mean difference between person and item scores of 0.33 ± 0.53 logits (scale range, 2 to -2) indicates that the items are well targeted to the populations. The PCA (dimensionality measures) shows the percentage of variance explained by measures equal to 26.4 per cent (modelled 26.9 per cent) and an eigenvalue of the first contrast of 2.5, which demonstrated good stability.The 21-item CVLS is a valid uni-dimensional child self-report instrument for the assessment of the impact of amblyopia on vision-related quality of life in children with and without amblyopia living in Saudi Arabia.

Eye health-care in Australia encompasses patients with chronic disorders being referred to ophthalmologists for detailed assessment and subsequent management. An increasing case load and relative decrease in ophthalmologists predicted over the next few years portend of an upcoming bottleneck in care delivery. To improve the efficiency and effectiveness of patient care within a rapidly changing health system, we propose that minor adjustments to existing services could improve the proficiency of resources. Such changes will require service providers to rethink their positions and roles and actively collaborate with each other for improved patient outcomes.

PurposeThe purpose of this paper is to provide an evidence‐base for home modification guidelines for people with visual impairment due to age‐related macular degeneration (AMD), from the perspective of people with AMD, by exploring the home modifications they find useful and would recommend to other people with visual impairment due to AMD as being effective.Design/methodology/approachPeople with impairments may not be aware of their own coping with inability strategies until they are asked to express their strategies. A qualitative approach using semi‐structured individual interviews was used to elicit the perspectives of people with AMD with regards to their preferred home modification interventions. Interviews were recorded and then transcribed verbatim into text for thematical analysis using Nvivo 8.FindingsIn total, 31 individuals (aged 79.1±5.6 years) with AMD and no other ocular diseases were recruited from a low vision clinic or the Macular Degeneration Foundation database in a metropolitan city. Interviewees had not received any formal home modification assessment from a government provider. Nevertheless, 70 per cent of participants stated that they undertook home modifications themselves or with the assistance of family and friends. The most important functional modifications as perceived by the participants concerned the installation of hand rails, non‐slip matting, colour contrasting safety stair nosing, single lever taps, slip resistant flooring, lift chairs and motion sensors that activated pathway lighting. Kitchens, steps and bathrooms were perceived as hazardous locations. Most participants had difficulties with reading fine‐print material on kitchen appliances, washing machines, microwave ovens and remote controls for electronic devices in the home.Originality/valueAn evidence‐base for useful home modifications as suggested by people with visual impairment was perceived to be a valuable resource for other people with visual impairment who may not yet have developed adaptive strategies. Industrial and interior designers and low vision rehabilitation services who aim to improve functionality of the home environment will also find these suggestions useful.

Purpose\ud \ud The visual evoked potential (VEP) provides a time series signal response to an external visual stimulus at the location of the visual cortex. The major VEP signal components, peak latency and amplitude, may be affected by disease processes. Additionally, the VEP contains fine detailed and non-periodic structure, of presently unclear relevance to normal function, which may be quantified using the fractal dimension. The purpose of this study is to provide a systematic investigation of the key parameters in the measurement of the fractal dimension of VEPs, to develop an optimal analysis protocol for application.\ud \ud Methods\ud \ud VEP time series were mathematically transformed using delay time, τ, and embedding dimension, m, parameters. The fractal dimension of the transformed data was obtained from a scaling analysis based on straight line fits to the numbers of pairs of points with separation less than r versus log(r) in the transformed space. Optimal τ, m, and scaling analysis were obtained by comparing the consistency of results using different sampling frequencies. The optimised method was then piloted on samples of normal and abnormal VEPs.\ud \ud Results\ud \ud Consistent fractal dimension estimates were obtained using τ = 4 ms, designating the fractal dimension = D2 of the time series based on embedding dimension m = 7 (for 3606 Hz and 5000 Hz), m = 6 (for 1803 Hz) and m = 5 (for 1000Hz), and estimating D2 for each embedding dimension as the steepest slope of the linear scaling region in the plot of log(C(r)) vs log(r) provided the scaling region occurred within the middle third of the plot. Piloting revealed that fractal dimensions were higher from the sampled abnormal than normal achromatic VEPs in adults (p = 0.02). Variances of fractal dimension were higher from the abnormal than normal chromatic VEPs in children (p = 0.01).\ud \ud Conclusions\ud \ud A useful analysis protocol to assess the fractal dimension of transformed VEPs has been developed.

Recent advances in technology and the increased use of tablet computers for mobile health applications such as vision testing necessitate an understanding of the behavior of the displays of such devices, to facilitate the reproduction of existing or the development of new vision assessment tests. The purpose of this study was to investigate the physical characteristics of one model of tablet computer (iPad mini Retina display) with regard to display consistency across a set of devices (15) and their potential application as clinical vision assessment tools. Once the tablet computer was switched on, it required about 13 min to reach luminance stability, while chromaticity remained constant. The luminance output of the device remained stable until a battery level of 5%. Luminance varied from center to peripheral locations of the display and with viewing angle, whereas the chromaticity did not vary. A minimal (1%) variation in luminance was observed due to temperature, and once again chromaticity remained constant. Also, these devices showed good temporal stability of luminance and chromaticity. All 15 tablet computers showed gamma functions approximating the standard gamma (2.20) and showed similar color gamut sizes, except for the blue primary, which displayed minimal variations. The physical characteristics across the 15 devices were similar and are known, thereby facilitating the use of this model of tablet computer as visual stimulus displays.

Objective The prospective efficacy of peripheral retinal prostheses for guiding orientation and mobility in the absence of residual vision, as compared to an implant for the central visual field (VF), was evaluated using simulated prosthetic vision (SPV). Approach Sighted volunteers wearing a head-mounted display performed an obstacle circumvention task under SPV. Mobility and orientation performance with three layouts of prosthetic vision were compared: peripheral prosthetic vision of higher visual acuity (VA) but limited VF, of wider VF but limited VA, as well as centrally restricted prosthetic vision. Learning curves using these layouts were compared fitting an exponential model to the mobility and orientation measures. Main results Using peripheral layouts, performance was superior to the central layout. Walking speed with both higher-acuity and wider-angle layouts was 5.6% higher, and mobility errors reduced by 46.4% and 48.6%, respectively, as compared to the central layout. The wider-angle layout yielded the least number of collisions, 63% less than the higher-acuity and 73% less than the central layout. Using peripheral layouts, the number of visual-scanning related head movements was 54.3% (higher-acuity) and 60.7% (wider-angle) lower, as compared to the central layout, and the ratio of time standing versus time walking was 51.9% and 61.5% lower, respectively. Learning curves did not differ between layouts, except for time standing versus time walking, where both peripheral layouts achieved significantly lower asymptotic values compared to the central layout. Significance Beyond complementing residual vision for an improved performance, peripheral prosthetic vision can effectively guide mobility in the later stages of retinitis pigmentosa (RP) without residual vision. Further, the temporal dynamics of learning peripheral and central prosthetic vision are similar. Therefore, development of a peripheral retinal prosthesis and early implantation to alleviate VF constriction in RP should be considered to extend the target group and the time of benefit for potential retinal prosthesis implantees.

Transient chromatic pattern visual evoked potentials (VEPs) have been found to be less repeatable in morphology in children than in adults at low to moderate chromatic contrasts. The purpose of this study is to investigate whether low repeatability of VEP components can be associated with high alpha power, in a comparison of alpha activity in children and adults. Transient chromatic contrast and achromatic resolution VEPs were recorded in children (n = 14, mean 9.6 years) and adults (n = 12, mean 21.8 years) with normal vision and assessed for repeatability. Isoluminant chromatic (magenta-cyan) and luminance-modulated achromatic grating stimuli were presented at and above psychophysical threshold levels, in pattern onset-offset at 2 Hz temporal frequency. EEGs (eyes closed and open) were recorded as single sweeps (1 s long) over three 30 s periods while facing a uniform computer display. An index of VEP detectability by observation was developed based on VEP component repeatability. The index was examined for correlations with alpha-wave parameters. Alpha power was calculated as the sum of the powers of 8-13 Hz frequencies of the EEG sweeps (using the discrete Fourier transform). Alpha power variability was calculated using the standard deviation of the powers of each sweep in a 30 s time period. The children had significantly higher alpha powers than the adults for both the eyes-open and eyes-closed conditions. Alpha power variability was significantly higher for the eyes-open condition only. There was no relationship between alpha power parameters and index of VEP detectability by observation for both the chromatic and achromatic grating stimuli. Poor repeatability of transient pattern VEPs is not associated with high alpha power or its variability in EEG measurements in older children or young adults at Oz.

Age-related macular degeneration (AMD) is a major cause of visual impairment and blindness among people aged over 60 years in developed countries and it is forecast that the prevalence of AMD will increase. AMD is characterised by progressive loss of central vision leading to loss of functional vision (the ability to undertake visually guided activities). Functional vision may be assessed using ‘activity of daily living (ADL) instruments, which assess independent living skills, such as ability to read, write, recognise faces and objects and other daily living activities. AMD also affects the quality of life and impedes healthy independent ageing. Individuals confronted with disability may create novel strategies to cope. This case study will highlight how the ability to function may be greater than expected, based on the level of visual function and ADL instrument measures. This study shows how appropriate devices and the exercise of creativity can aid in the development of novel coping strategies. For example, threading a needle is often regarded as a highly-visually demanding task requiring fine visual resolution and is used by some ADL instruments to measure functional visual ability in people with visual impairment. This clinical communication highlights strategies that do not rely heavily on vision and may be used for threading needles and other related tasks.

PurposeTo investigate whether exposure to occupational levels of organic solvents in the dry cleaning industry is associated with neurotoxic symptoms and visual deficits in the perception of basic visual features such as luminance contrast and colour, higher level processing of global motion and form (Experiment 1), and cognitive function as measured in a visual search task (Experiment 2).MethodsThe Q16 neurotoxic questionnaire, a commonly used measure of neurotoxicity (by the World Health Organization), was administered to assess the neurotoxic status of a group of 33 dry cleaners exposed to occupational levels of organic solvents (OS) and 35 age-matched non dry-cleaners who had never worked in the dry cleaning industry. In Experiment 1, to assess visual function, contrast sensitivity, colour/hue discrimination (Munsell Hue 100 test), global motion and form thresholds were assessed using computerised psychophysical tests. Sensitivity to global motion or form structure was quantified by varying the pattern coherence of global dot motion (GDM) and Glass pattern (oriented dot pairs) respectively (i.e., the percentage of dots/dot pairs that contribute to the perception of global structure). In Experiment 2, a letter visual-search task was used to measure reaction times (as a function of the number of elements: 4, 8, 16, 32, 64 and 100) in both parallel and serial search conditions.ResultsDry cleaners exposed to organic solvents had significantly higher scores on the Q16 compared to non dry-cleaners indicating that dry cleaners experienced more neurotoxic symptoms on average. The contrast sensitivity function for dry cleaners was significantly lower at all spatial frequencies relative to non dry-cleaners, which is consistent with previous studies. Poorer colour discrimination performance was also noted in dry cleaners than non dry-cleaners, particularly along the blue/yellow axis. In a new finding, we report that global form and motion thresholds for dry cleaners were also significantly higher and almost double than that obtained from non dry-cleaners. However, reaction time performance on both parallel and serial visual search was not different between dry cleaners and non dry-cleaners.ConclusionsExposure to occupational levels of organic solvents is associated with neurotoxicity which is in turn associated with both low level deficits (such as the perception of contrast and discrimination of colour) and high level visual deficits such as the perception of global form and motion, but not visual search performance. The latter finding indicates that the deficits in visual function are unlikely to be due to changes in general cognitive performance.

Chromatic contrast thresholds may be estimated from transient VEPs by measuring the peak-to-peak amplitude at a range of stimulus levels followed by extrapolation to zero amplitude. However, there have been reports of failure of this technique when applied to the transient chromatic VEP due to variability of amplitude, difficulties with component identification and poor correlation of amplitude with stimulus level. The aim of our study was to compare methods of transient VEP chromatic contrast threshold estimation in terms of success rate and comparison with psychophysical threshold. We found each of the methods we investigated to have a high success rate, and in most cases VEP and psychophysical thresholds did not differ significantly.

Background. There is limited research conducted on uncorrected refractive errors, presbyopia, and spectacles use among the elderly population in residential care in developing countries such as India. We conducted a cross-sectional study among elderly in residential care to assess the spectacle coverage and spectacles usage in the south Indian state of Andhra Pradesh. Methods. All 524 residents in the 26 “homes for aged” institutions in the district were enumerated. Eye examination was performed that included visual acuity (VA) assessment for distant and near vision. A questionnaire was used to collect information on spectacles use. Results. 494/524 individuals were examined, 78% were women, and 72% had no education. The mean age of participants was 70 years. The spectacle coverage for refractive errors was 35.1% and 23.9% for presbyopia. The prevalence of current use and past use of spectacles was 38.5% (95% CI: 34.2–42.8; ) and 17.2% (95% CI: 13.9–42.8), respectively. Conclusions. There is low spectacle coverage for both refractive errors and presbyopia among elderly individuals in residential care in the south Indian state of Andhra Pradesh. Appropriate service delivery systems should be developed to reach out this vulnerable group of seniors on a priority basis.

Purpose. We investigated the effects of image contrast, stimulus density, and viewing distance upon a multifocal steady-state visual evoked potential (MSV) method. Methods. Fourteen adults with normal vision (mean age = 27.0 ± 6.6 years; 6 males) participated in the study. Each of the stimulus regions of the multifocal ensembles presented a contrast modulated grating, displaying spatial and temporal frequencies that evoke the spatial frequency doubling illusion. All subjects were tested at five contrasts: 0.06, 0.11, 0.22, 0.45, and 0.89; viewed at 16, 32, and 128 cm. A multivariate linear model estimated factors for each stimulus region, recording channel, number of stimuli (9 or 17 regions), and sex; and covariates for contrast, and octaves of viewing distance, and age. Results. The responses per unit area for the 17-region display were significantly larger than for the 9-region display (P < 10−12). The contrast-response function could be described by a power law with exponent 0.068 (P < 0.008). The effect of viewing distance was small but significant: response amplitude dropped by −0.17 ± 0.03 dB per octave of viewing distance (P < 10−6), or 10% over 8 octaves. Conclusions. The response per unit area indicated that cortical folding diminishes responses to larger stimuli. Viewing distance did not greatly affect response amplitude. This suggested that we can use similar, but scaled, stimuli to study central and peripheral disease. The rapidly saturating contrast responses imply that there would be nothing lost from testing at contrasts as low as 20% given that higher, saturating contrasts might mask visual field defects.

To measure contrast-response functions (CRFs) for 9 visual field (VF) regions and nonlinear interactions between regions using a multifocal steady-state VEP (MSV).Ten normal adults were tested (51.7 ± 16.9 yr, 5 females). Stimuli resembling those of the Frequency Doubling Technology (FDT) perimeter were presented in 9 VF regions simultaneously, which were modulated at incommensurate temporal frequencies (mean 19.7 Hz). Responses were recorded to 11 contrasts from 3% to 89%, using 8 scalp electrodes. Two repeats of a 20s duration stimulus were averaged for each contrast.The CRFs were log-linear except for a depression near 7% contrast (p=0.0008), which was prominent in the central VF. The effects of VF region, stimulus frequency and recording electrode were significant (all p0.016). Significant responses at frequencies corresponding to interactions between VF regions also appeared. Electrodes that were best for the interactions and second harmonic responses differed, suggesting different cortical sources.Despite short recording durations the saturating CRFs meant that significant responses could be measured to low contrasts, and be distinguished from nonlinear interactions.Recording MSVs to low contrast FDT-like stimuli might be useful for quantifying damage by glaucoma and other visual disorders.

Purpose. To assess the postural stability and gait characteristics of adults with age-related maculopathy (ARM) and to identify the visual factors associated with postural stability and gait in this clinical population. Methods. Participants included 80 individuals with a range of severity of ARM (mean age, 77.2 years). Binocular visual function measures included visual acuity, contrast sensitivity, and merged binocular visual fields. Postural stability was assessed on both a firm and a foam surface using center-of-pressure measures derived from a force platform. Forty three of the participants underwent a three-dimensional motion analysis to quantify gait characteristics, including walking velocity, proportion of time spent with both feet in contact with the ground (double-support time), stride length, and step width. Results. After adjustment for age, sex, self-reported physical function, and cataract severity, all the vision measures were significantly associated with postural stability on the foam surface, with contrast sensitivity being the strongest correlate. In the analysis of the gait measures, only contrast sensitivity was significantly associated with walking velocity, step width, or stride length, whereas contrast sensitivity and visual field loss were both significantly associated with double-support time. Conclusions. Impaired contrast sensitivity was associated with postural instability, slower walking velocity, increased step width, and reduced stride length. Impairments in either contrast sensitivity or visual fields were associated with increased double-support time. This result suggests that loss of contrast sensitivity and visual fields in patients with ARM can lead to balance and mobility problems.

Measures of chromatic contrast sensitivity in children are lower than those of adults. This may be related to immaturities in signal processing at or near threshold. We have found that children’s VEPs in response to low contrast supra-threshold chromatic stimuli are more intra-individually variable than those recorded from adults. Here, we report on linear and nonlinear analyses of chromatic VEPs recorded from children and adults. Two measures of signal-to-noise ratio are similar between the adults and children, suggesting that relatively high noise is unlikely to account for the poor clarity of negative and positive peak components in the children’s VEPs. Nonlinear analysis indicates higher complexity of adults’ than children’s chromatic VEPs, at levels of chromatic contrast around and well above threshold.

Objective. The prospective efficacy of a future peripheral retinal prosthesis complementing residual vision to raise mobility performance in non-end stage retinitis pigmentosa (RP) was evaluated using simulated prosthetic vision (SPV). Approach. Normally sighted volunteers were fitted with a wide-angle head-mounted display and carried out mobility tasks in photorealistic virtual pedestrian scenarios. Circumvention of low-lying obstacles, path following, and navigating around static and moving pedestrians were performed either with central simulated residual vision of 10° alone or enhanced by assistive SPV in the lower and lateral peripheral visual field (VF). Three layouts of assistive vision corresponding to hypothetical electrode array layouts were compared, emphasizing higher visual acuity, a wider visual angle, or eccentricity-dependent acuity across an intermediate angle. Movement speed, task time, distance walked and collisions with the environment were analysed as performance measures. Main results. Circumvention of low-lying obstacles was improved with all tested configurations of assistive SPV. Higher-acuity assistive vision allowed for greatest improvement in walking speeds—14% above that of plain residual vision, while only wide-angle and eccentricity-dependent vision significantly reduced the number of collisions—both by 21%. Navigating around pedestrians, there were significant reductions in collisions with static pedestrians by 33% and task time by 7.7% with the higher-acuity layout. Following a path, higher-acuity assistive vision increased walking speed by 9%, and decreased collisions with stationary cars by 18%. Significance. The ability of assistive peripheral prosthetic vision to improve mobility performance in persons with constricted VFs has been demonstrated. In a prospective peripheral visual prosthesis, electrode array designs need to be carefully tailored to the scope of tasks in which a device aims to assist. We posit that maximum benefit might come from application alongside existing visual aids, to further raise life quality of persons living through the prolonged early stages of RP.

Visual evoked potentials (VEPs) may be analyzed by examination of the morphology of their components, such as negative (N) and positive (P) peaks. However, methods that rely on component identification may be unreliable when dealing with responses of complex and variable morphology; therefore, objective methods are also useful. One potentially useful measure of the VEP is the correlation dimension. Its relevance to the visual system was investigated by examining its behavior when applied to the transient VEP in response to a range of chromatic contrasts (42%, two times psychophysical threshold, at psychophysical threshold) and to the visually unevoked response (zero contrast). Tests of nonlinearity (e.g., surrogate testing) were conducted. The correlation dimension was found to be negatively correlated with a stimulus property (chromatic contrast) and a known linear measure (the Fourier-derived VEP amplitude). It was also found to be related to visibility and perception of the stimulus such that the dimension reached a maximum for most of the participants at psychophysical threshold. The latter suggests that the correlation dimension may be useful as a diagnostic parameter to estimate psychophysical threshold and may find application in the objective screening and monitoring of congenital and acquired color vision deficiencies, with or without associated disease processes.