What is low vision? A re-evaluation of definitions

Assessing REALTER simulator: analysis of ocular movements in simulated low-vision conditions with extended reality technology

Immersive technology, such as extended reality, holds promise as a tool for educating ophthalmologists about the effects of low vision and for enhancing visual rehabilitation protocols. However, immersive simulators have not been evaluated for their ability to induce changes in the oculomotor system, which is crucial for understanding the visual experiences of visually impaired individuals. This study aimed to assess the REALTER (Wearable Egocentric Altered Reality Simulator) system's capacity to induce specific alterations in healthy individuals' oculomotor systems under simulated low-vision conditions. We examined task performance, eye movements, and head movements in healthy participants across various simulated scenarios. Our findings suggest that REALTER can effectively elicit behaviors in healthy individuals resembling those observed in individuals with low vision. Participants with simulated binocular maculopathy demonstrated unstable fixations and a high frequency of wide saccades. Individuals with simulated homonymous hemianopsia showed a tendency to maintain a fixed head position while executing wide saccades to survey their surroundings. Simulation of tubular vision resulted in a significant reduction in saccade amplitudes. REALTER holds promise as both a training tool for ophthalmologists and a research instrument for studying low vision conditions. The simulator has the potential to enhance ophthalmologists' comprehension of the limitations imposed by visual disabilities, thereby facilitating the development of new rehabilitation protocols.

Barriers and enablers to low vision care and rehabilitation in sub-Saharan Africa within a global context

Low vision is an uncorrectable form of visual impairment that affect millions of people worldwide. Low vision care and rehabilitation are essential to improving the independence of affected individuals. Even though sub-Saharan Africa has one of the highest burdens of low vision globally, there are inadequate care and rehabilitation services in most countries and in some cases they are non-existent This scoping review aimed to identify the barriers and enablers to low vision care and rehabilitation in sub-Saharan Africa and assess these within the global context. The review was conducted using the five-step Arksey and O'Malley framework. Search terms were formulated based on the research questions and a search strategy was designed to search for eligible research articles from electronic databases; Pubmed, Ovid, Medline, and Embase. The data was screened by two members of the research team in accordance with set inclusion and exclusion criteria. Twenty-five out of 260 articles satisfied the inclusion criteria for the study. Inadequate low vision care infrastructure and supplies, non-standardised training of low vision care providers, health system failure and poor awareness of low vision care were the main barriers noted by eye care practitioners. Patients living with low vision cited the cost and availability of low vision aids, societal stigma, and poor awareness of services as the main barriers. No direct enablers were identified in sub-Saharan Africa; however, practitioners suggested improved training in low vision as a potential enabler. The barriers to low vision care and rehabilitation services identified were not unique to sub-Saharan Africa when viewed within a global context. Adopting and adapting solutions from other countries may therefore assist in improving low vision care and rehabilitation in sub-Saharan Africa.

Validation of the Waterloo Differential Visual Acuity Test (WatDAT) and Comparison With Existing Pediatric Tests of Visual Acuity

Purpose

The new Waterloo Differential Acuity Test (WatDAT) is designed to allow recognition visual acuity (VA) measurement in children before they can typically undertake matching tests. The study purpose was to validate WatDAT in adults with normal and reduced VA.

Methods

Eighty adults (18 to <40 years of age) participated (32 normal VA, 12 reduced VA, and 36 simulated reduced VA). Monocular VA was measured on two occasions in random order for WatDAT (versions with 3 and 5 distractors for Faces and Patti Pics house among circles), Lea Symbols, Kay Pictures and Patti Pics matching tests, Teller Acuity Cards, Cardiff Acuity Test, and Early Treatment Diabetic Retinopathy Study (ETDRS) letter chart. Pediatric tests were validated against ETDRS using limits of agreement (LoA), sensitivity, and specificity. The LoA for repeatability were also determined.

Results

WatDAT showed minimal bias compared with ETDRS, and LoAs, which were similar to pediatric matching tests (0.241-0.250). Both preferential looking tests showed higher bias and LoAs than ETDRS. Matching tests showed good agreement with ETDRS, except for Kay Pictures and Lea Uncrowded test, which overestimated VA. WatDAT showed high sensitivity (>0.96) and specificity (>0.79), which improved with criterion adjustment and were significantly higher than for the preferential looking tests. LoA for repeatability for WatDAT 3 Faces and WatDAT 5 Faces were comparable with the ETDRS.

Conclusions

WatDAT demonstrates good agreement and repeatability compared with the gold-standard ETDRS letter chart, and performed better than preferential looking tests, the alternative until a child can undertake a matching VA test.

Translational Relevance

Good validity of the Waterloo Differential Acuity Test was demonstrated in adults as a first step to showing its potential for detecting childhood visual disorders.

Life-Course Persistent Antisocial Behavior and Accelerated Biological Aging in a Longitudinal Birth Cohort

Prior research shows that individuals who have exhibited antisocial behavior are in poorer health than their same-aged peers. A major driver of poor health is aging itself, yet research has not investigated relationships between offending trajectories and biological aging. We tested the hypothesis that individuals following a life-course persistent (LCP) antisocial trajectory show accelerated aging in midlife. Trajectories of antisocial behavior from age 7 to 26 years were studied in the Dunedin Multidisciplinary Health and Development Study, a population-representative birth cohort (N = 1037). Signs of aging were assessed at age 45 years using previously validated measures including biomarkers, clinical tests, and self-reports. First, we tested whether the association between antisocial behavior trajectories and midlife signs of faster aging represented a decline from initial childhood health. We then tested whether decline was attributable to tobacco smoking, antipsychotic medication use, debilitating illnesses in adulthood, adverse exposures in childhood (maltreatment, socioeconomic disadvantage) and adulthood (incarceration), and to childhood self-control difficulties. Study members with a history of antisocial behavior had a significantly faster pace of biological aging by midlife, and this was most evident among individuals following the LCP trajectory (β, 0.22, 95%CI, 0.14, 0.28, p ≤ 0.001). This amounted to 4.3 extra years of biological aging between ages 25-45 years for Study members following the LCP trajectory compared to low-antisocial trajectory individuals. LCP offenders also experienced more midlife difficulties with hearing (β, -0.14, 95%CI, -0.21, -0.08, p ≤ 0.001), balance (β, -0.13, 95%CI, -0.18, -0.06, p ≤ 0.001), gait speed (β, -0.18, 95%CI, -0.24, -0.10, p ≤ 0.001), and cognitive functioning (β, -0.25, 95%CI, -0.31, -0.18, p ≤ 0.001). Associations represented a decline from childhood health. Associations persisted after controlling individually for tobacco smoking, antipsychotic medication use, midlife illnesses, maltreatment, socioeconomic status, incarceration, and childhood self-control difficulties. However, the cumulative effect of these lifestyle characteristics together explained why LCP offenders have a faster Pace of Aging than their peers. While older adults typically age-out of crime, LCP offenders will likely age-into the healthcare system earlier than their chronologically same-aged peers. Preventing young people from offending is likely to have substantial benefits for health, and people engaging in a LCP trajectory of antisocial behaviors might be the most in need of health promotion programs. We offer prevention and intervention strategies to reduce the financial burden of offenders on healthcare systems and improve their wellbeing.

Current directions in visual perceptual learning

The visual expertise of adult humans is jointly determined by evolution, visual development, and visual perceptual learning. Perceptual learning refers to performance improvements in perceptual tasks after practice or training in the task. It occurs in almost all visual tasks, ranging from simple feature detection to complex scene analysis. In this Review, we focus on key behavioral aspects of visual perceptual learning. We begin by describing visual perceptual learning tasks and manipulations that influence the magnitude of learning, and then discuss specificity of learning. Next, we present theories and computational models of learning and specificity. We then review applications of visual perceptual learning in visual rehabilitation. Finally, we summarize the general principles of visual perceptual learning, discuss the tension between plasticity and stability, and conclude with new research directions.

Self-reported driving difficulty in patients with bilateral cataract

PURPOSE

The presence of cataract causes reduction in visual acuity (VA) and contrast sensitivity (CS) and thus can affect individual's daily activities. The aim of this study was to investigate self-reported driving difficulty in patients with bilateral cataract.

METHODS

A total of 99 participants aged 50 and above, with bilateral cataract, who possessed a valid driving license and drove regularly were chosen for this cross-sectional study that looked into their visual functions (VA and CS) and driving difficulty using the self-reported Driving Difficulty Questionnaire.

RESULTS

The mean age of the participants was 65.04±7.22 years old. Results showed that the mean composite driving difficulty score was 83.18±11.74 and most of the participants were having difficulty for driving in the rain (73.7%) and at night (85.9%). Furthermore, the study found that there was a significant correlation between driving difficulty score and CS (rs = 0.40, p = 0.03). However, there was no significant correlation between driving difficulty score and VA (rs = -0.14, p = 0.17). A linear regression was calculated to predict driving difficulty score based on binocular CS and a significant regression equation was found (F (1,28) = 8.115, p = 0.008) with R² of 0.225. Drivers with bilateral cataract will most likely experience some forms of difficulty, especially when driving under low contrast conditions.

CONCLUSION

The findings of this study demand that a comprehensive eye examination should be made compulsory for older adult drivers when issuing or renewing their driving license for the safety of all road users.

Visual functions associated with on-road performance by older drivers evaluated by a certified driving rehabilitation specialist

PURPOSE

To assess associations between visual function and on-road driving performance evaluated by a certified driving rehabilitation specialist (CDRS).

METHODS

Adults aged 70 and older enrolled and completed assessments of visual acuity, contrast sensitivity, visual processing speed, visual field sensitivity, motion perception and spatial ability. At follow-up, on-road driving performance was evaluated on a 15-mile route. Age-adjusted odds ratios and 95% confidence intervals (95% CIs) were used to associate worse CDRS composite score and CDRS global rating for those with poorer visual function compared to those with better scores and ratings.

RESULTS

For the 144 participants who enrolled, completed vision testing and the on-road driving evaluation, the mean age was 79.2 (5.1) and 45.8% were female. The odds of worse CDRS global rating and composite score were significantly associated with moderately and severely impaired visual processing speed under divided attention (all p < 0.05). Those with poorer motion perception were at greater odds of a worse CDRS composite score (OR: 2.67, 95% CI: 1.14-6.26).

CONCLUSIONS

The CDRS composite score of on-road driving performance by older adults was associated with slowed visual processing and impaired motion perception, suggesting that older driver performance, as rated by a CDRS, relies on visual skills. The CDRS global rating was also associated with impaired visual processing speed. The literature suggests impairments in these same visual functions elevate crash risk. While the results provide additional evidence suggesting these functional measures are associated with driving, further work is needed to identify and assess visual measures most closely related to driving safety and performance among older adults to better inform interventions, policy and future research.

Self-report Measures of Hearing and Vision in Older Adults Participating in the Canadian Longitudinal Study of Aging are Explained by Behavioral Sensory Measures, Demographic, and Social Factors

OBJECTIVES

Our objectives were to (1) determine the prevalence of self-reported hearing, vision, and dual sensory (both vision and hearing) difficulties in older Canadian adults; (2) examine the association between self-report and behavioral sensory measures; and (3) controlling for behavioral sensory measures, examine variables that might explain the self-reported sensory difficulty, including age, sex, cultural background, socioeconomic status, nonsensory comorbidities, cognitive function, and social factors.

DESIGN

We used baseline data collected from the 30,097 participants of the comprehensive cohort of the Canadian Longitudinal Study on Aging. Participants who were 45 to 85 years of age (mean age = 63 years, SD = ± 10.25) were recruited using provincial health registries and random-digit dialing. Analyses were conducted for the sample as a whole or stratified by age. Behavioral sensory data for hearing (pure-tone audiometry) and vision (pinhole-corrected visual acuity) were collected at 11 data collection sites. Self-reported sensory and personal data were obtained through in-person interviews. "Difficulty" was defined as a response of "fair" or "poor" (versus "excellent," "very good" or "good") to questions about hearing ability (using a hearing aid if used) and vision (using glasses or corrective lenses if used). Individuals with both hearing and vision difficulties were defined as having dual sensory difficulties. Variables associated with self-reported sensory difficulties were analyzed with multiple regression models.

RESULTS

Objective 1. The prevalence of impairments based on behavioral measures was higher than the prevalence of difficulties based on self-report measures. The prevalence based on both types of measures increased with age, but the increase was steeper for behavioral measures. Objective 2. In addition to the expected positive associations between self-report and behavioral measures of hearing [odds ratio (OR) = 2.299)] and vision (OR = 15.247), self-reported sensory difficulty was also explained by other within-modality sensory variables, such as the symmetry of impairment and the use of aids. Objective 3. Controlling for behavioral measures of hearing (better-ear pure-tone average) or vision (better-eye visual acuity), older participants were significantly less likely than younger participants to self-report sensory difficulty. Sensory difficulties were reported more often by males and by those with more comorbid health conditions. Compared to those who did not report vision difficulties, those who did report them were more likely to also report hearing difficulties (OR = 2.921) and vice versa (OR = 2.720). There were modality-specific associations with variables relevant to social participation; for example, independent life space was associated with hearing difficulties, and perceived availability of social support and loneliness with vision difficulties.

CONCLUSIONS

The low prevalence of self-reported sensory difficulties relative to the behavioral measures of sensory impairments indicates that (a) a simple screening question about sensory ability may not be sufficient to identify older adults who are in the early stages of sensory decline, and (b) self-reported sensory ability is associated with sensory and nonsensory factors. Age, gender, and comorbidities are the most notable nonsensory predictors for both self-reported hearing and vision. These findings shed light on how the self-reported sensory difficulties of older adults may reflect clinical measures of sensory impairment as well as nonsensory factors.

Left Turns by Older Drivers With Vision Impairment: A Naturalistic Driving Study

BACKGROUND AND OBJECTIVES

Older drivers are overrepresented in collisions at intersections while making left turns across oncoming traffic. Using naturalistic driving methods, we evaluated the association between vision impairment and their left-turn characteristics.

RESEARCH DESIGN AND METHODS

In this prospective, observational study, vision impairment as defined by visual acuity, contrast sensitivity, visual processing speed, visual field sensitivity, and motion perception was assessed in drivers ≥70 years old. Data acquisition systems were installed in their personal vehicles recording video and vehicle kinematics. Driving during everyday life was recorded for 6 months. Data analysts evaluated a temporal data window surrounding randomly selected left turns at 4-way intersections. Left-turn traversals and turning behavior were evaluated in terms of age-adjusted associations with vision impairment.

RESULTS

The sample consisted of 151 older drivers. The number of turns studied was 473; 265 turns were rated as unsafe traversals, and 201 as problematic turning behavior. Drivers with slowed visual processing speed and visual field impairment were less likely to exhibit unsafe traversals (p < .05); those with worse contrast sensitivity, slowed visual processing speed, and visual field impairment were less likely to exhibit problematic turning behavior (p < .05).

DISCUSSION AND IMPLICATIONS

Using naturalistic driving, our study suggests older drivers with vision impairment exhibit better performance in making left turns than those without deficits, which contradicts older driver studies on left turns using driving simulators and on-road driving evaluations. Our findings suggest more cautious and self-regulatory behavior, which are consistent with older visually impaired drivers' commonly expressed concerns about their driving difficulties.

Naturalistic Driving Techniques and Association of Visual Risk Factors With At-Fault Crashes and Near Crashes by Older Drivers With Vision Impairment

Importance

Government motor vehicle crash reports used in the study of driver safety can be biased and incomplete. Naturalistic driving methods using in-vehicle instrumentation have been developed in recent years to objectively measure crashes and near crashes as they occur on the road using video and vehicle kinematic data.

Objective

To examine visual risk factors associated with at-fault crashes and near crashes among older drivers, most of whom have age-related eye conditions associated with vision impairment.

Design, Setting, and Participants

This prospective cohort study was conducted at an academic ophthalmology clinic from January 1, 2015, to November 10, 2018, among 154 adults 70 years of age or older who were legally licensed in Alabama and who reported currently driving at least 4 days per week; 137 of 151 participants (90.7%) had an age-related eye condition in at least 1 eye. Drivers participated in a baseline visual function assessment followed by installation of a data acquisition system recording multichannel synchronized video and vehicle kinematics in their personal vehicle. Drivers were instructed to drive for 6 months as they normally would during everyday life. Statistical analysis was performed from June 15 to September 15, 2020.

Main Outcomes and Measures

The rate of combined incident at-fault crashes and near crashes, defined by the number of events and the number of miles driven.

Results

The sample consisted of 154 drivers (85 men [55.2%]; mean [SD] age, 79.3 [5.1] years). Visual functions associated with crash and near-crash involvement included impaired contrast sensitivity (rate ratio [RR], 2.7; 95% CI, 1.3-5.5), moderate (RR, 2.3; 95% CI, 1.1-4.9) and severe (RR, 5.0; 95% CI, 2.2-11.7) slowing in visual processing speed, and elevated motion perception thresholds for a drifting grating (RR, 1.9; 95% CI, 1.1-3.5). Those with impaired peripheral visual field sensitivity had increased rates of crashes and near crashes (RR, 1.8; 95% CI, 1.0-3.3); however, this finding was not statistically significant (P = .07).

Conclusions and Relevance

With the use of naturalistic driving methods in which crashes and near crashes involving older drivers are objectively measured as they occur on the road, associations have been identified between impaired contrast sensitivity, slowed visual processing speed, and impaired motion perception and an increased rate of a combined total of at-fault crashes and near crashes.

Everyday visual demands of people with low vision: A mixed methods real-life recording study

Research has demonstrated that low vison aids (LVAs) can have a positive impact on the functional sight of those living with sight loss. Step changes in technology are now enabling new wearable LVAs with greater potential than those available previously. For these novel devices to receive increased acceptance and therefore adoption by those with sight loss, visual task demands have to be understood more clearly in order to enable better alignment between device design and user requirements. The aim of this study was to quantify these requirements. Thirty-two participants aged 18 to 87 wore a spectacle-mounted video camera to capture and narrate all everyday situations in which they would use a “perfect” sight aid during 1 week. Captured scenes were analyzed through categorization and computational image analysis. Results showed large variation in activities and lifestyles. Participants reported no available sight aid or coping strategy for 57% of the recorded activities. Reading made up 49% of all recorded tasks, the other half comprising non-textual information. Overall, 75% of captured activities were performed ad hoc (duration of 0–5 minutes), 78% occurred indoors, 58% occurred at home, 48% were lit by natural light, 68% included the object of interest within reach, and 69% required a single focus plane only. Around half of captured objects of interest had a size of 2 degrees visual angle (2.08 logarithm of the minimum angle of resolution [logMAR]) or smaller. This study highlights the need for a sight aid that can make both textual and non-textual scenes accessible while offering flexibility to accommodate individual lifestyles.

Reduced visual acuity is mirrored in low vision imagery

Research has examined the nature of visual imagery in normally sighted and blind subjects, but not in those with low vision. Findings with normally sighted subjects suggest that imagery involves primary visual areas of the brain. Since the plasticity of visual cortex appears to be limited in adulthood, we might expect imagery of those with adult-onset low vision to be relatively unaffected by these losses. But if visual imagery is based on recent and current experience, we would expect images of those with low vision to share some properties of impaired visual perception. We examined key parameters of mental images reported by normally sighted subjects, compared to those with early- and late-onset low vision, and with a group of subjects with restricted visual fields using an imagery questionnaire. We found evidence that those with reduced visual acuity report the imagery distances of objects to be closer than those with normal acuity and also depict objects in imagery with lower resolution than those with normal visual acuity. We also found that all low vision groups, like the normally sighted, image objects at a substantially greater distance than when asked to place them at a distance that 'just fits' their imagery field (overflow distance). All low vision groups, like the normally sighted, showed evidence of a limited visual field for imagery, but our group with restricted visual fields did not differ from the other groups in this respect. We conclude that imagery of those with low vision is similar to that of those with normal vision in being dependent on the size of objects or features being imaged, but that it also reflects their reduced visual acuity. We found no evidence for a dependence on imagery of age of onset or number of years of vision impairment.

Relationship between refractive correction, visual symptoms, and optical device selection for low-vision patients in Taiwan

According to Taiwan optometry act, low-vision services, such as refractive correction and low vision assessment, are now included in Optometric profession. This study was designed to investigate the efficiency of refractive correction and the relationship between refractive correction, eye diseases, visual symptoms, and optical device selection for patients with low vision.

METHODS

This study involved a total of 220 participants aged from 7 to 99, with 119 males and 101 females. All of them were referred from three institutes of Taiwan Resource Portal of Assistive Technology under the supervision of the Ministry of Health and Welfare during Feb 2016 to Jan 2018. Accordingly, 42, 76, and 102 of the participants were identified as having mild, moderate, and severe visual impairments, respectively, by five experienced and licensed optometrists for this comprehensive low vision examination.

RESULTS

The most common eye diseases in this study were retinal disease, cataract, glaucoma, and optic nerve hypoplasia; some of the participants had multiple eye diseases while participating in the study. Except visual acuity decrease, eye diseases were highly correlated with participants' visual symptoms. Refractive correction is the first step in low-vision examination, therefore, it might be much helpful to some types of eye diseases, visual symptoms, and to the decisions of optical devices for low-vision patients. The results herein suggest that color vision and contrast sensitivity should be taken into consideration when calculating the second optical magnifying power after refractive correction.

CONCLUSIONS

Refractive correction is necessary for the treatment of patients' visual symptoms and also for the prescription of low-vision aids.

The Prevalence of Hearing, Vision, and Dual Sensory Loss in Older Canadians: An Analysis of Data from the Canadian Longitudinal Study on Aging

The purpose of this study was to describe the prevalence of hearing loss (HL), vision loss (VL), and dual sensory loss (DSL) in Canadians 45–85 years of age. Audiometry and visual acuity were measured. Various levels of impairment severity were described. Results were extrapolated to the 2016 Canadian population. In 2016, 1,500,000 Canadian males 45–85 years of age had at least mild HL, 1,800,000 had at least mild VL, and 570,000 had DSL. Among females, 1,200,000 had at least mild HL, 2,200,000 had at least mild VL, and 450,000 had DSL. Among Canadians 45–85 years of age, mild, moderate, and severe HL was prevalent among 13.4 per cent, 3.7 per cent, and 0.4 per cent of males, and among 11.3 per cent, 2.3 per cent, and 0.2 per cent of females, respectively. Mild and moderate, or severe VL was prevalent among 19.8 per cent and 2.4 per cent of males, and among 23.9 per cent and 2.6 per cent of females, respectively. At least mild DSL was prevalent among 6.4 per cent of males and 6.1 per cent of females.

Towards developing a test of global motion for use with Paralympic athletes

The Paralympic classification system for visual impairment only assesses static visual acuity and static visual field despite many Paralympic sports being dynamic in nature. As a first step towards determining whether motion perception tests should be used in Paralympic classification, we assessed whether motion coherence thresholds could be measured when visual acuity or visual fields were impaired at levels consistent with the current Paralympic classification criteria. Visual acuity and visual field impairments corresponding to Paralympic classification criteria were simulated in normally sighted individuals and motion coherence thresholds were measured. Mild-to-moderate visual acuity impairments had no effect on motion coherence thresholds. The most severe Paralympic class of acuity impairment (≥2.6 logMAR) significantly elevated thresholds. A trend towards superior motion coherence thresholds in the peripheral visual field compared to the central visual field was also present. Global motion perception appears to be measurable under simulated visual impairments that are consistent with the Paralympic classification. Poorer global motion perception was found for visual acuities >2.6 logMAR and visual fields <10° in diameter. Further research is needed to investigate the relationship between global motion perception and sports performance in athletes with real visual impairment.

Benefit of an electronic head-mounted low vision aid

PURPOSE

To evaluate the efficacy of electronic head-mounted low vision aid (e-LVA) SightPlus (GiveVision, UK, givevision.net) and to determine which people with low vision would see themselves likely using an e-LVA like this.

METHODS

Sixty participants with low vision aged 18 to 93 used SightPlus during an in-clinic study session based on a mixed methods design. Visual acuity (ETDRS), contrast sensitivity (Pelli-Robson) and reading performance (MNREAD) were measured binocularly at baseline (no device), with the device in 'normal' mode (zoom only), and with preferred enhanced mode (zoom and one of four digital image enhancements). At the end of the session, a short questionnaire recorded willingness to use an e-LVA like SightPlus, potential use cases, positive/negative comments and adverse effects.

RESULTS

Binocular distance visual acuity improved significantly by 0.63 logMAR on average (p < 0.0001) to 0.20 logMAR. Contrast sensitivity improved significantly by 0.22 log units (p < 0.0001) to 1.21 log units with zoom only and by 0.40 log units to 1.37 log units with zoom and preferred image enhancement. Reading performance improved significantly for near visual acuity and critical print size (p < 0.015), although reading speed significantly decreased (p < 0.0001). Nearly half (47%) of the participants indicated they would use an e-LVA like SightPlus, especially for television, reading and entertainment (e.g. theatre). Multivariate logistic regression showed that proportion of lifetime affected by sight loss, baseline contrast sensitivity and use of electronic LVAs explained 41% of the variation in willingness to use.

CONCLUSIONS

SightPlus improves visual function in people with low vision and would be used in its current form by one half of the people who tried it. Adverse effects were infrequent and resolved when the device was removed. Future work should focus on comparing e-LVAs through repeatable real-world tasks and impact on quality of life.

Functional Evaluation of the Visual Pathway in Patients with Multiple Sclerosis Using a Multifunction Stimulator Monitor

Objectives

To assess the capability of the vision monitor unit Monpack One of detecting visual function alterations in patients with multiple sclerosis (MS) and to evaluate the correlation between structural retinal parameters and functional measurements obtained with this device.

Methods

Forty-eight patients with MS and 46 healthy controls were included in a cross-sectional study. All participants underwent a complete functional evaluation of the visual pathway, which included low-contrast visual acuity (LCVA), contrast sensitivity vision (CSV), automated perimetry, multifocal visual evoked potentials (mfVEPs), and pattern electroretinogram (ERG). All tests were performed using the vision monitor unit Monpack One (Metrovision, France), a multifunction stimulator device. Retinal structural measurements were obtained in all subjects using Triton swept source optical coherence tomography (Topcon, Japan).

Results

Patients with MS presented reduced low-contrast VA (p < 0.001) and reduced CSV at medium (p=0.001, p=0.013) and low (p=0.001, p=0.002) spatial frequencies. All visual field parameters were found to be altered in MS patients compared with controls (≤0.001). Patients with MS presented lower amplitude of the P100 waveform of the mfVEP in areas corresponding to central (p < 0.001), inferonasal (p=0.001), and inferotemporal (p=0.003) retina. The pattern ERG did not show significant differences. Significant correlations were observed between structural retinal measurements and functional parameters, especially between the inner macular areas and measurements corresponding to contrast sensitivity and perimetry indexes.

Conclusions

Patients with MS present visual dysfunction detectable with the vision monitor unit Monpack One. This device may be a fast and useful tool to provide a full evaluation of axonal damage in patients with multiple sclerosis.

How People with Low Vision Achieve Magnification in Digital Reading

SIGNIFICANCE

Digital reading displays provide opportunities for enhancing accessibility of text for low vision. How are these displays used by people in their daily lives?

PURPOSE

Subjects responded to an online survey concerning their vision history, reading technology, display preferences, and reading habits. Here, we report on findings concerning acuity and magnification.

METHODS

The survey asked subjects to arrange a text passage for typical reading and to report viewing distance, screen dimensions, and the number of characters per line. Seventy-five adult subjects (most with early-onset low vision, few with central field loss) completed all survey questions relevant to the analysis of acuity and magnification. Mean acuity was .92 logMAR (range, 0.1 to 1.6), and mean age was 44.8 years (range, 18 to 71 years). Twelve normally sighted controls reported the same information while viewing the passage on cell phones, tablets, and computers.

RESULTS

The controls had a mean viewing distance of 38.7 cm and a mean x-height of 1.38 mm. For all three types of devices, angular x-height was 0.21° (close to laboratory estimates of the critical print size for reading). Low vision subjects showed decreasing viewing distance and increasing print size with larger values of logMAR acuity. Most of the low vision subjects achieved their desirable magnification by a combination of reduced viewing distance and increased physical letter size. The majority (54 of 75) relied more on letter-size magnification. Relative to the controls, regression analysis revealed that a typical low vision subject with logMAR acuity of 1.0 reduced viewing distance by a factor of 2.8 and enlarged physical print size by a factor of 6.

CONCLUSIONS

Our survey shows that people with a wide range of acuities are engaged in digital reading. Our subjects achieved desirable magnification primarily by enlarging physical character size and to a lesser extent by reducing viewing distance.

Visual Performance in the "Real World": Contrast Sensitivity, Visual Acuity, and Effects of Macular Carotenoids

Visual acuity (VA) is compared to contrast sensitivity (CS) testing in assessing "real-world" visual performance, and it is recommended that both should be measured routinely in the clinic. The role of nutritional intervention in improving visual performance is reviewed and emphasized. A brief history and illustration of both VA and CS, within the scope of visual performance, is presented. Parameters for effective CS testing in the clinic, and guidelines for interpretation of results, including a new model for understanding the visual impact of changes in CS, are also presented. Relevant research that supports the use of the macular carotenoids lutein, zeaxanthin, and meso-zeaxanthin to enhance visual performance is reviewed with suggested guidelines for supplementation. CS testing is easily performed at a single intermediate target size and is an excellent tool for the accurate assessment of a patient's overall visual experience. Research continues to uncover the strong link between nutrition and visual performance; the macular carotenoids appear to be especially effective in this regard, and their benefits to visual performance now importantly include contrast sensitivity. Clinicians can provide an improved level of care by incorporating into the examination protocol CS testing and, where appropriate, nutritional counseling and intervention.

Perceiving blurry scenes with translational optic flow, rotational optic flow or combined optic flow

Perceiving the spatial layout of objects is crucial in visual scene perception. Optic flow provides information about spatial layout. This information is not affected by image blur because motion detection uses low spatial frequencies in image structure. Therefore, perceiving scenes with blurry vision should be effective when optic flow is available. Furthermore, when blurry images and optic flow interact, optic flow specifies spatial relations and calibrates blurry images. Calibrated image structure then preserves spatial relations specified by optic flow after motion stops. Thus, perceiving blurry scenes should be stable when optic flow and blurry images are available. We investigated the types of optic flow that facilitate recognition of blurry scenes and evaluated the stability of performance. Participants identified scenes in blurry videos when viewing single frames and the entire videos that contained translational flow (Experiment 1), rotational flow (Experiment 2) or both (Experiment 3). When first viewing the blurry images, participants identified a few scenes. When viewing blurry video clips, their performance improved with translational flow, whether it was available alone or in combination with rotational flow. Participants were still able to perceive scenes from static blurry images one week later. Therefore, translational flow interacts with blurry image structures to yield effective and stable scene perception. These results imply that observers with blurry vision may be able to identify their surrounds when they locomote.

Peripapillary microcirculation in Leber hereditary optic neuropathy

PURPOSE

In this prospective observational comparative case series, we aimed to study the peripapillary capillary network with spectral-domain optical coherence tomography angiography (OCT-A) in Leber hereditary optic neuropathy (LHON).

METHODS

Twelve eyes of six individuals, of these three males (five eyes) after clinical onset of visual impairment were imaged by OCT-A with scans centred on optic discs. Control group consisted of 6 eyes with no visual impairment.

RESULTS

The three affected individuals lost vision 6 years (at age 22 years), 2 years and 3 months (at age 26 years) and 1 year and 2 months (at age 30 years) prior to OCT-A examination. All five affected eyes had alterations in density of the radial peripapillary microvascular network at the level of retinal nerve fibre layer, including an eye of a patient treated with idebenone that underwent almost full recovery (best corrected visual acuity 0.87). Interestingly, the other eye showed normal ocular findings 14 months after onset. Results of OCT-A examination in this eye were unfortunately inconclusive due to a delineation error. At the level of the ganglion cell layer differences could be also noted, but only in two severely affected individuals. There were no differences between unaffected mutation carriers and control eyes.

CONCLUSION

Optical coherence tomography angiography scans confirmed that the peripapillary microvascular network is highly abnormal in eyes manifesting visual impairment due to LHON. These findings support the hypothesis that microangiopathy contributes to the development of vision loss in this mitochondrial disorder.

Prevalence of vision loss among hospital in-patients; a risk factor for falls?

PURPOSE

Despite poor vision being a risk factor for falls, current hospital policies and practices often do not include a vision assessment at patient admission or in the hospital's incident reporting system when a fall occurs. Our purpose was to document the prevalence of vision loss in hospital general medicine units to increase awareness of poor vision as a potential risk factor for falls that occur within the hospital, and inform future preventative practice.

METHODS

This cross-sectional study took place in medicine units of an acute care hospital. Participants were adult in-patients. Visual acuity (VA), contrast sensitivity and stereoacuity were measured, and patients were screened for field loss, extinction and neglect.

RESULTS

115 participants took part (average age 67 ± 17, 48% female). Overall, 89% had a visual impairment defined as being outside the age-norms for one or more vision measure, 62% had low vision, and 36% had vision loss equivalent to legal blindness [VA equal to or poorer than 1.0 logMAR (6/60, 20/200) or ≥10x below age-norms]. There was a considerable discrepancy between the prevalence of low vision and the percentage of patients who reported an ocular diagnosis that would result in visual loss (30%). Ten patients fell during the study period, and of these 100% had visual impairment, 90% had low vision and 60% had vision loss equivalent to legal blindness, which compares to 58%, 22% and 9% for non-fallers. Similar high prevalences were found in those whose reason for admission to the hospital was a fall (92%, 63% and 33% respectively).

CONCLUSIONS

Vision loss has a high prevalence among patients in hospital medicine units, and is higher still among those who fall. Since vision loss may be a contributing factor to falls that occur in hospitals, implementing an assessment of vision at hospital admission would be useful to alert staff to those patients who are at risk for falls due to poor vision, so that preventative measures can be applied.

Definition of blindness under National Programme for Control of Blindness: Do we need to revise it?

A review appropriateness of the current definition of blindness under National Programme for Control of Blindness (NPCB), Government of India. Online search of peer-reviewed scientific published literature and guidelines using PubMed, the World Health Organization (WHO) IRIS, and Google Scholar with keywords, namely blindness and visual impairment, along with offline examination of reports of national and international organizations, as well as their cross-references was done until December 2016, to identify relevant documents on the definition of blindness. The evidence for the historical and currently adopted definition of blindness under the NPCB, the WHO, and other countries was reviewed. Differences in the NPCB and WHO definitions were analyzed to assess the impact on the epidemiological status of blindness and visual impairment in India. The differences in the criteria for blindness under the NPCB and the WHO definitions cause an overestimation of the prevalence of blindness in India. These variations are also associated with an over-representation of refractive errors as a cause of blindness and an under-representation of other causes under the NPCB definition. The targets for achieving elimination of blindness also become much more difficult to achieve under the NPCB definition. Ignoring differences in definitions when comparing the global and Indian prevalence of blindness will cause erroneous interpretations. We recommend that the appropriate modifications should be made in the NPCB definition of blindness to make it consistent with the WHO definition.

Diffusion tensor imaging for multilevel assessment of the visual pathway: possibilities for personalized outcome prediction in autoimmune disorders of the central nervous system

The afferent visual pathway represents the most frequently affected white matter pathway in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). Diffusion tensor imaging (DTI) can reveal microstructural or non-overt brain tissue damage and quantify pathological processes. DTI facilitates the reconstruction of major white matter fiber tracts allowing for the assessment of structure-function and damage-dysfunction relationships. In this review, we outline DTI studies investigating the afferent visual pathway in idiopathic optic neuritis (ON), NMOSD, and MS. Since MS damage patterns are believed to depend on multiple factors, i.e., ON (anterior visual pathway damage), inflammatory lesions (posterior visual pathway damage), and global diffuse inflammatory and neurodegenerative processes, comprehensive knowledge on different contributing factors using DTI in vivo may advance our understanding of MS disease pathology. Combination of DTI measures and visual outcome parameters yields the potential to improve routine clinical diagnostic procedures and may further the accuracy of individual prognosis with regard to visual function and personalized disease outcome. However, due to the inherent limitations of DTI acquisition and post-processing techniques and the so far heterogeneous and equivocal data of previous studies, evaluation of the true potential of DTI as a possible biomarker for afferent visual pathway dysfunction is still substantially limited. Further research efforts with larger longitudinal studies and standardized DTI acquisition and post-processing validation criteria are needed to overcome current DTI limitations. DTI evaluation at different levels of the visual pathway has the potential to provide markers for individual damage evaluation in the future. As an imaging biomarker, DTI may support individual outcome prediction during personalized treatment algorithms in MS and other neuroinflammatory diseases, hereby leveraging the concept of predictive, preventive, and personalized medicine in the field of clinical neuroimmunology.

Validity of low-contrast letter acuity as a visual performance outcome measure for multiple sclerosis

Low-contrast letter acuity (LCLA) has emerged as the leading outcome measure to assess visual disability in multiple sclerosis (MS) research. As visual dysfunction is one of the most common manifestations of MS, sensitive visual outcome measures are important in examining the effect of treatment. Low-contrast acuity captures visual loss not seen in high-contrast visual acuity (HCVA) measurements. These issues are addressed by the MS Outcome Assessments Consortium (MSOAC), including representatives from advocacy organizations, Food and Drug Administration (FDA), European Medicines Agency (EMA), National Institute of Neurological Disorders and Stroke (NINDS), academic institutions, and industry partners along with persons living with MS. MSOAC goals are acceptance and qualification by regulators of performance outcomes that are highly reliable and valid, practical, cost-effective, and meaningful to persons with MS. A critical step is elucidation of clinically relevant benchmarks, well-defined degrees of disability, and gradients of change that are clinically meaningful. This review shows that MS and disease-free controls have similar median HCVA, while MS patients have significantly lower LCLA. Deficits in LCLA and vision-specific quality of life are found many years after an episode of acute optic neuritis, even when HCVA has recovered. Studies reveal correlations between LCLA and the Expanded Disability Status Score (EDSS), Multiple Sclerosis Functional Composite (MSFC), retinal nerve fiber layer (RNFL) and ganglion cell layer plus inner plexiform layer (GCL + IPL) thickness on optical coherence tomography (OCT), brain magnetic resonance imaging (MRI), visual evoked potential (VEP), electroretinogram (ERG), pupillary function, and King-Devick testing. This review also concludes that a 7-point change in LCLA is clinically meaningful. The overall goal of this review is to describe and characterize the LCLA metric for research and clinical use among persons with MS.

Perceptual training yields rapid improvements in visually impaired youth

Visual function demands coordinated responses to information over a wide field of view, involving both central and peripheral vision. Visually impaired individuals often seem to underutilize peripheral vision, even in absence of obvious peripheral deficits. Motivated by perceptual training studies with typically sighted adults, we examined the effectiveness of perceptual training in improving peripheral perception of visually impaired youth. Here, we evaluated the effectiveness of three training regimens: (1) an action video game, (2) a psychophysical task that combined attentional tracking with a spatially and temporally unpredictable motion discrimination task, and (3) a control video game. Training with both the action video game and modified attentional tracking yielded improvements in visual performance. Training effects were generally larger in the far periphery and appear to be stable 12 months after training. These results indicate that peripheral perception might be under-utilized by visually impaired youth and that this underutilization can be improved with only ~8 hours of perceptual training. Moreover, the similarity of improvements following attentional tracking and action video-game training suggest that well-documented effects of action video-game training might be due to the sustained deployment of attention to multiple dynamic targets while concurrently requiring rapid attending and perception of unpredictable events.

Compensation for Blur Requires Increase in Field of View and Viewing Time

Spatial resolution is an important factor for human pattern recognition. In particular, low resolution (blur) is a defining characteristic of low vision. Here, we examined spatial (field of view) and temporal (stimulus duration) requirements for blurry object recognition. The spatial resolution of an image such as letter or face, was manipulated with a low-pass filter. In experiment 1, studying spatial requirement, observers viewed a fixed-size object through a window of varying sizes, which was repositioned until object identification (moving window paradigm). Field of view requirement, quantified as the number of "views" (window repositions) for correct recognition, was obtained for three blur levels, including no blur. In experiment 2, studying temporal requirement, we determined threshold viewing time, the stimulus duration yielding criterion recognition accuracy, at six blur levels, including no blur. For letter and face recognition, we found blur significantly increased the number of views, suggesting a larger field of view is required to recognize blurry objects. We also found blur significantly increased threshold viewing time, suggesting longer temporal integration is necessary to recognize blurry objects. The temporal integration reflects the tradeoff between stimulus intensity and time. While humans excel at recognizing blurry objects, our findings suggest compensating for blur requires increased field of view and viewing time. The need for larger spatial and longer temporal integration for recognizing blurry objects may further challenge object recognition in low vision. Thus, interactions between blur and field of view should be considered for developing low vision rehabilitation or assistive aids.

Relationship between Visual Dysfunction and Retinal Changes in Patients with Multiple Sclerosis

Aim

To evaluate structural changes in the retina and their correlation with visual dysfunction in patients with multiple sclerosis.

Methods

Patients with multiple sclerosis (n = 84) and healthy controls (n = 84) underwent structural evaluation of the retinal nerve fiber layer, and macular and ganglion cell layer thicknesses using Spectral domain optical coherence tomography (SD-OCT). All subjects underwent high and low contrast visual acuity, color vision (using the Farnsworth and L´Anthony desaturated D15 color tests), and contrast sensitivity vision using the Pelli Robson chart and CSV 1000E test.

Results

Macular, retinal nerve fiber layer, and ganglion cell layer thinning was observed in multiple sclerosis patients compared to healthy controls (p<0.05). High- and low-contrast visual acuity and contrast sensitivity vision at four different spatial frequencies were significantly reduced in comparison with healthy subjects (p<0.05). Macular, retinal nerve fiber layer and ganglion cell layer measurements correlated with high and low contrast visual acuity, and contrast sensitivity vision. Contrast sensitivity vision was the functional parameter that most strongly correlated with the structural measurements in multiple sclerosis and was associated with ganglion cell layer measurements. The L´Anthony color vision score (age-corrected color confusion index) was associated with macular measurements.

Conclusions

Patients with multiple sclerosis had visual dysfunction that correlated with structural changes evaluated by SD-OCT. Macular and ganglion cell layer measurements may be good indicators of visual impairment in multiple sclerosis patients.

A Proposed Model for Integrated Low-Vision Rehabilitation Services in Canada

PURPOSE

The provision and funding of low-vision rehabilitation (LVR) are very variable across Canada. Quebec is well served by 14 government-funded rehabilitation centers. In most provinces, there are no such multidisciplinary services-optometrists offer LVR from their offices to a greater or lesser degree or undertake assessments in centers run by CNIB (formerly Canadian National Institute for the Blind). No integrated model for LVR exists across Canada. This document proposes such a model, which focuses on the profession of optometry, but may also be applicable to ophthalmology.

METHODS

This article describes different models of LV provision, the evidence for their relative effectiveness, the current situation in Canada, including the variability between areas and the need to increase referrals to LVR, and the current international consensus for LV provision. With the projected increase in people with LV, a generally accepted LV model for Canada is required to improve patient care.

RESULTS

It has become recognized in the global community that a tiered system may be required to provide for patients who range in their visual rehabilitation needs and geographic locations. The proposed LVR model includes three levels: 1. Screening/recognition of a potential patient with LV followed by appropriate triage. All optometrists should be involved at this level. 2. Management of the patient with minimum visual impairment/disability. This level of LVR can take place in a local optometry office with a minimal of extra equipment or devices. Level 3: Comprehensive LVR for patients with more vision loss and greater disabilities. Level 3 requires collaboration with other professionals, and three mechanisms are proposed by this which may take place.

CONCLUSIONS

The proposed model is expected to be useful for future education, policy decisions, and collaboration in Canada, and it may also be of interest for the development of LV services in other countries.

Improving the legibility of prescription medication labels for older adults and adults with visual impairment

OBJECTIVES

Most current prescription labels fail to meet print guidelines, especially in print size. We therefore compared the legibility of current prescription medication labels against the legibility of prototype labels, based on current guidelines for legibility.

METHOD

Sample medication labels were obtained from pharmacies, and prototype medication labels were developed according to legibility guidelines from nongovernmental organizations and pharmacy organizations. Three groups of participants, consisting of older adults with normal vision, older adults with visual impairment and younger adults with visual impairment (total N = 71) took part. Participants were asked to read and rank the labels. Reading speed and accuracy were determined.

RESULTS

Accuracies were high (75%-100%), and there were no significant differences between samples or prototypes or between groups. Prototypes, however, were read faster than samples (p < 0.001). Subjectively, participants preferred the largest print option (p < 0.001) and instructions with the numbers written in highlighted uppercase words (p < 0.001).

DISCUSSION

The results indicate that improvements to the label would include larger print size, a consistent layout with left justification and using upper case with highlighting for emphasis of the numbers in the instructions.

Effect of reduced visual acuity on precision of two-dimensional tracing movements

PURPOSE

We intended to assess consequences of reduced visual acuity for performance in a natural simple motor task (tracing) using objective kinematic performance measures. Specifically, we intended to elucidate the kind of relationship between the task performance and best corrected binocular visual acuity and to determine the threshold of visual acuity when task performance starts to deteriorate.

METHODS

Ninety-five individuals with different best corrected visual acuity participated in the study (age 49±12 years, mean±SD, 27 men and 68 women). The participants manually traced maze-like visual patterns of different spatial complexity presented on the screen of a portable notebook computer using Clinical Kinematic Assessment Tool software. Tracing error was computed as performance measure in each trial with a spatial pattern matching technique - rigid point set registration method.

RESULTS

The segmented linear regression analysis showed that the relation between visual acuity and tracing errors was best described with a regression function having a break point between two data segments. Tracing performance was unaffected by values of visual acuity below 0.2 on logMAR scale, but when logMAR values increased above this critical limit (i.e. when visual acuity is further reduced), tracing errors linearly increased. The rate of the increase of the tracing error correlated with the complexity of visual stimulus shape.

CONCLUSION

Testing of fine motor functions with objective kinematic measures during visuomotor tasks may help differentiating between actual effects of reduced visual acuity on eye-hand coordination in individuals with similar levels of impairment of visual acuity.

Low-vision service provision by optometrists: a Canadian nationwide survey

PURPOSE

To document the degree to which Canadian optometrists are involved in the provision of low-vision (LV) care and their referral patterns. To investigate the barriers to providing optometric low-vision services (LVS).

METHODS

Practicing optometrists across Canada were randomly sampled and invited to participate in a questionnaire that included questions on personal profile, primary practice profile, levels of LV care offered, patterns of referral, and barriers to provision of LV care. Questions included a combination of multiple choice and open-ended formats, and included hypothetical cases.

RESULTS

A total of 459 optometrists responded (response rate, 24.8%). Optometrists estimated that 1% (range, 0 to 100%) of their patients were LV patients yet also estimated that 10% of their patients had acuity equal to or worse than 20/40. Thirty-five percent of respondents indicated that their primary practice offered LV care, 75.6% would manage a patient with minimum disability and simple goals themselves, whereas 10.7% would manage a patient with more than minimal visual disability who needed more specialized LV devices (e.g., telescopes, electronic aids, and custom-designed microscopes); 84.3% of optometrists would assess for basic magnification and lighting in a hypothetical patient with early age-related macular degeneration, whereas 15% would undertake full LV rehabilitation in advanced age-related macular degeneration. Optometrists commonly referred to CNIB (formerly the Canadian National Institute for the Blind), yet only 10.7% of respondents almost always received a written report after referral. Those who would not undertake LV assessment stated that they lacked the knowledge, equipment, or experience; that LV assessment is too time consuming; and that the cost is too prohibitive.

CONCLUSIONS

This is the first comprehensive study of LVS provision by optometrists in Canada. In order for optometrists to become more involved in LVS, there is a need for more LV education, provincial health coverage of optometric LVS, and better collaboration communication between LV providers.

Acute optic neuritis: Unmet clinical needs and model for new therapies

Idiopathic demyelinating optic neuritis (ON) most commonly presents as acute unilateral vision loss and eye pain and is frequently associated with multiple sclerosis. Although emphasis is often placed on the good recovery of high-contrast visual acuity, persistent deficits are frequently observed in other aspects of vision, including contrast sensitivity, visual field testing, color vision, motion perception, and vision-related quality of life. Persistent and profound structural and functional changes are often revealed by imaging and electrophysiologic techniques, including optical coherence tomography, visual-evoked potentials, and nonconventional MRI. These abnormalities can impair patients' abilities to perform daily activities (e.g., driving, working) so they have important implications for patients' quality of life. In this article, we review the sequelae from ON, including clinical, structural, and functional changes and their interrelationships. The unmet needs in each of these areas are considered and the progress made toward meeting those needs is examined. Finally, we provide an overview of past and present investigational approaches for disease modification in ON.

A randomised controlled trial of a self-management programme for low vision implemented in low vision rehabilitation services

OBJECTIVE

To investigate the effectiveness of a low vision self-management programme (LVSMP) in older adults.

METHODS

Participants (n=153) were existing clients of a national low vision rehabilitation organisation randomly allocated to usual services (n=60) or usual services plus LVSMP (n=93). The LVSMP was an 8-week group programme facilitated by low vision counsellors. The primary outcome was vision-specific quality of life (QoL) measured using the Impact of Vision Impairment (IVI) questionnaire. Secondary outcomes emotional well-being, self-efficacy and adaptation to vision loss were measured using the depression, anxiety, stress scale (DASS), general self-efficacy scale (GSES), and short form adaptation to age-related vision loss scale (AVL12).

RESULTS

At one and six month follow-up assessments, no significant between-group differences were found for vision-specific QoL, emotional well-being, adaptation to vision loss or self-efficacy (p>0.05). Univariate and multivariate analyses revealed no impact of the intervention on outcome measures.

CONCLUSIONS

In contrast to previous work, our study found limited benefit of a LVSM programme on QoL for older adults accessing low vision services.

PRACTICE IMPLICATIONS

When implementing self-management programmes in low vision rehabilitation settings, issues of client interest, divergence of need, programme accessibility and fidelity of intervention delivery need to be addressed.

Vision and vision-related outcome measures in multiple sclerosis

Visual impairment is a key manifestation of multiple sclerosis. Acute optic neuritis is a common, often presenting manifestation, but visual deficits and structural loss of retinal axonal and neuronal integrity can occur even without a history of optic neuritis. Interest in vision in multiple sclerosis is growing, partially in response to the development of sensitive visual function tests, structural markers such as optical coherence tomography and magnetic resonance imaging, and quality of life measures that give clinical meaning to the structure-function correlations that are unique to the afferent visual pathway. Abnormal eye movements also are common in multiple sclerosis, but quantitative assessment methods that can be applied in practice and clinical trials are not readily available. We summarize here a comprehensive literature search and the discussion at a recent international meeting of investigators involved in the development and study of visual outcomes in multiple sclerosis, which had, as its overriding goals, to review the state of the field and identify areas for future research. We review data and principles to help us understand the importance of vision as a model for outcomes assessment in clinical practice and therapeutic trials in multiple sclerosis.

Vision impairment and dual sensory problems in middle age

PURPOSE

Vision and hearing impairments are known to increase in middle age. In this study we describe the prevalence of vision impairment and dual sensory impairment in UK adults aged 40-69 years in a very large and recently ascertained data set. The associations between vision impairment, age, sex, socioeconomic status, and ethnicity are reported.

METHODS

This research was conducted using the UK Biobank Resource, with subsets of UK Biobank data analysed with respect to self-report of eye problems and glasses use. Better-eye visual acuity with habitually worn refractive correction was assessed with a logMAR chart (n = 116,682). Better-ear speech reception threshold was measured with an adaptive speech in noise test, the Digit Triplet Test (n = 164,770). Prevalence estimates were weighted with respect to UK 2001 Census data.

RESULTS

Prevalence of mild visual impairment (VA >0.1 logMAR (6/7.5, 20/25) and ≥0.48 (6/18, 20/60)) and low vision (VA >0.48 (6/18, 20/60) and ≥1.3 (6/120, 20/400)) was estimated at 13.1% (95% CI 12.9-13.4) and 0.8% (95% CI 0.7-0.9), respectively. Use of glasses was 88.0% (95% CI 87.9-88.1). The prevalence of dual sensory impairment was 3.1% (95% CI 3.0-3.2) and there was a nine-fold increase in the prevalence of dual sensory problems between the youngest and oldest age groups. Older adults, those from low socioeconomic and ethnic minority backgrounds were most at risk for vision problems.

CONCLUSIONS

Mild vision impairment is common in middle aged UK adults, despite widespread use of spectacles. Increased likelihood of vision impairment with older age and with ethnic minorities is of concern given ageing and more ethnically diverse populations. Possible barriers to optometric care for those from low socioeconomic and ethnic minority backgrounds may require attention. A higher than expected prevalence of dual impairment suggests that hearing and vision problems share common causes. Optometrists should consider screening for hearing problems, particularly among older adults.

Safety on stairs: influence of a tread edge highlighter and its position

BACKGROUND

Falls sustained when descending stairs are the leading cause of accidental death in older adults. Highly visible edge highlighters/friction strips (often set back from the tread edge) are sometimes used to improve stair safety, but there is no evidence for the usefulness of either.

OBJECTIVE

To determine whether an edge highlighter and its location relative to the tread edge affect foot placement/clearance and accidental foot contacts when descending stairs.

METHOD

Sixteen older adults (mean±1SD age; 71±7years) with normal vision (experiment 1) and eight young adults (mean±1SD age; 24±4years) with visual impairment due to simulated age-related cataract (experiment 2) completed step descent trials during which a high contrast edge highlighter was either not present, placed flush with the tread edge, or set back from the edge by 10mm or 30mm. Foot placement/clearance and the number of accidental foot contacts were compared across conditions.

RESULTS

In experiment 1, a highlighter set back by 30mm led to a reduction in final foot placement (p<0.001) and foot clearance (p<0.001) compared to a highlighter placed flush with the tread edge, and the percentage of foot clearances that were less than 5mm increased from 2% (abutting) to 17% (away30). In experiment 2, a highlighter placed flush with the tread edge led to a decrease in within-subject variability in final foot placement (p=0.004) and horizontal foot clearance (p=0.022), a decrease in descent duration (p=0.009), and a decrease in the number of low clearances (<5mm, from 8% to 0%) and the number of accidental foot contacts (15% to 3%) when compared to a tread edge with no highlighter present.

CONCLUSIONS

Changes to foot clearance parameters as a result of highlighter presence and position suggest that stairs with high-contrast edge highlighters positioned flush with the tread edge will improve safety on stairs, particularly for those with age-related visual impairment.

Retinal nerve fibre layer thickness and contrast sensitivity in HIV-infected individuals in South Africa: a case-control study

Background

Antiretroviral treatment (ART) has altered the spectrum of HIV-related eye disease, resulting in a lower prevalence of retinal opportunistic infections (OIs). However, abnormalities in visual function have been reported in HIV-infected individuals despite effective viral suppression and the absence of retinal OIs. These changes may be mediated by an HIV-associated ‘neuroretinal disorder’, characterized by changes in the retinal nerve fibre layer (RNFL). HIV infection may also be associated with accelerated biological aging. The aim of this study was to investigate the relationships between contrast sensitivity, RNFL thickness, HIV infection and frailty in South African adults.

Methods

Case-control study of 225 HIV-infected individuals without retinal OIs and 203 gender/age-matched HIV-seronegative individuals. Peri-papillary RNFL thickness was determined with spectral domain optical coherence tomography in four quadrants. CS was measured using a Pelli-Robson chart. Frailty was assessed using standard criteria. Multivariable linear and logistic regression were used to assess associations between HIV status and RNFL/CS and frailty.

Results

The median age of both groups was similar (41.2 vs. 41.9 years, p = 0.37). 88% of HIV-infected individuals were receiving ART and their median CD4 count was 468 cells/μl. Adjusted CS score was lower in HIV-infected participants compared to HIV-seronegative individuals (1.76 vs. 1.82, p = 0.002). Independent predictors of poor CS in the HIV-infected group were positive frailty status and current HIV viral load >2 log copies/ml. Lower CS score was also associated with thin temporal RNFL in HIV-infected individuals (p = 0.04). Superior quadrant RNFL thickness was greatest in ART-naïve participants relative to the HIV-uninfected group (p-trend = 0.04). Longer ART duration was associated with thinning of inferior and nasal RNFL quadrants (p-trend = 0.03 and 0.04, respectively).

Conclusions

Contrast sensitivity is reduced in HIV-infected individuals and functionally associated with frailty and unsuppressed viraemia. This may reflect structural changes in the RNFL that are evident despite the absence of OIs.

Prevalence and risk factors for eye diseases, blindness, and low vision in Lhasa, Tibet

AIM

To determine the prevalence and risk factors for eye diseases, blindness, and low vision in Tibet, and to assist the development of eye disease prevention and treatment schemes.

METHODS

We carried out a survey of eye diseases among a population living at high altitude. A total of 1 115 Tibetan permanent residents aged 40 years or older from the towns and villages of Qushui County, Lhasa Prefecture, Tibet Autonomous Region, participated in this study. All participants completed a detailed questionnaire, and underwent presenting and pinhole visual acuity tests, and a comprehensive ophthalmic examination.

RESULTS

There were 187 blind eyes (8.43%), 231 eyes with low vision (10.41%). The leading cause of visual impairment was cataract of 55.0% (101/187) blindness and of 50.2% (116/231) low vision, followed by fundus lesions of 22.9% blindness and 23.8% low vision, while only a low prevalence of glaucoma of 9.6% blindness and 1.7% low vision was observed. The analysis of 2 219 eyes showed that the most common external eye disease was pterygium (27.2%) in Tibet.

CONCLUSION

The high prevalence of blindness and low vision in the Tibetan population at high altitude is a serious public health issue. There is a need to establish and maintain an appropriate effective eye care program in Tibet.

The eye as a model of ageing in translational research--molecular, epigenetic and clinical aspects

The eye and visual system are valuable in many areas of translational research such as stem cell therapy, transplantation research and gene therapy. Changes in many ocular tissues can be measured directly, easily and objectively in vivo (e.g. lens transparency; retinal blood vessel calibre; corneal endothelial cell counts) and so the eye may also be a uniquely useful site as a model of ageing. This review details cellular, molecular and epigenetic mechanisms related to ageing within the eye, and describes ocular parameters that can be directly measured clinically and which might be of value in ageing research as the translational "window to the rest of the body". The eye is likely to provide a valuable model for validating biomarkers of ageing at molecular, epigenetic, cellular and clinical levels. A research agenda to definitively establish the relationship between biomarkers of ageing and ocular parameters is proposed.

Vision in multiple sclerosis: the story, structure-function correlations, and models for neuroprotection

Visual dysfunction is one of the most common clinical manifestations of multiple sclerosis (MS). Just over a decade ago, MS clinical trials did not include visual outcomes, but experts recognized the need for more sensitive measures of visual function. Low-contrast letter acuity emerged as the leading candidate to measure visual disability in MS, and subsequent studies found low-contrast acuity testing to correlate well with brain MRI lesion burden, visual-evoked potentials, quality of life (QOL), and retinal nerve fiber layer (RNFL) loss, as measured by optical coherence tomography (OCT). OCT in MS has allowed for assessment of structure-function correlations that make the anterior visual pathway and acute optic neuritis (ON) ideal models for testing novel agents for neuroprotection and repair. New therapies that reduce axonal loss by neuroprotective or myelin repair mechanisms can now be assessed noninvasively by OCT and coupled with visual function data. Based on OCT studies in MS, RNFL thickness is reduced significantly among patients (92 μm) vs controls (105 μm) and is particularly reduced in MS eyes with a history of ON (85 μm). Worsening of visual function by a clinically significant ≥ 7 letters or approximately 1.5 lines for low-contrast acuity is associated with approximately 4.5 μm reductions in RNFL thickness in MS eyes. Longitudinal studies of OCT have also shown RNFL axonal loss over time that occurs even in the absence of acute ON and that correlates with clinically meaningful worsening of vision and QOL, even in patients with benign MS. The latest OCT investigations involve high-resolution spectral-domain (SD) OCT with segmentation and measurement of specific retinal layers using computerized algorithms. These methods allow quantitation of ganglion cell (neuronal) layer loss and axonal degeneration in MS in vivo. In this review, we examine the data from these studies and ongoing trials that highlight the entity of ON as a model to investigate neuroprotection and neurorepair. In doing so, we also present representative group data from studies that have examined visual function, OCT measures, and QOL scales in patients with MS and ON and disease-free controls. These data, and those from recent meta-analyses, may be used to provide reference values for the development of clinical trial protocols.