Orientation and mobility training for adults with low vision

Navigating the Genetic Landscape: A Comprehensive Review of Novel Therapeutic Strategies for Retinitis Pigmentosa Management

Retinitis pigmentosa (RP) is a collection of retinal disorders characterized by the progressive degeneration of photoreceptor cells, leading to significant visual impairment and, in severe cases, blindness. RP affects individuals worldwide and can be inherited through various genetic patterns, making it a genetically diverse condition. Despite considerable advancements in diagnostic methods and supportive therapies, there is currently no cure for RP. The focus of existing management strategies is on slowing the progression of the disease and improving the quality of life for those affected. This comprehensive review explores the latest therapeutic approaches in the management of RP, highlighting advancements in genetic therapies, such as gene augmentation and editing, as well as cell-based treatments including stem cell transplantation and induced pluripotent stem cell (iPSC) technologies. Emerging methods like optogenetics and pharmacological interventions designed to preserve retinal function are also discussed. Additionally, the review examines technological innovations, including retinal prosthetics and the use of artificial intelligence, which hold the potential to revolutionize RP treatment. The challenges and limitations associated with these novel therapies, such as safety concerns, accessibility issues, and regulatory hurdles, are critically evaluated. By providing an overview of current research and future directions, this review aims to inform clinicians and researchers about the state of the art in RP treatment and the prospects for achieving significant therapeutic advancements.

The Underutilization of Mental Health Care Services in the Lives of People with Blindness or Visual Impairment: A Literature Review on Rehabilitation Factors Toward Provision

Purpose

Roughly 3 million adult Americans have a visual impairment or blindness, and over 4 million adults aged 40 and older. Despite data demonstrating an elevated prevalence of mental health symptoms in people with BVI, this population remains largely untreated. Given that people with BVI often interface with multiple systems of rehabilitative care that are designed to improve quality of life, the relatively low rates of initiation of mental health care services are particularly alarming. In this review, the systematic processes of mental health care services across pertinent rehabilitation groups are identified and critically examined.

Patients and Methods

A comprehensive literature review was conducted. The literature review utilized a critical systems typology, whereby relevant literature was selected, reviewed, and analyzed intra and extra organizationally. In addition, a thorough discussion of disability-related factors was provided, lending a socio-political lens to the problem.

Results

Considerable data indicates that short-term mental health care services for people with BVI are ineffective treatment methods, albeit primarily employed in health-rehabilitative processes. Multiple studies offered data indicating the presence of diverse and entangled mental health issues relative to vocational rehabilitation services, mobility tool utility, and emotional reactions to vision loss. Many studies suggested that disability identity work be integrated into health-rehabilitative processes for people with BVI.

Conclusion

To improve the utility of mental health care services for people with BVI, a reenergization of the mental health care needs of this population must occur. A critical podcast or forum focused on educating listeners about the health-rehabilitation factors that influence the provision of mental health care services can aid to improve future mental health policy and practice for people with BVI. Disability scholars need to advance research on integrating critical theories in work with people with BVI and accelerate qualitative, community-based methods to enhance understanding of this population and their unique mental health needs.

Cost-benefit analysis of orientation and mobility programs for adults with vision disability: a contingent valuation study

PURPOSE

The purpose of this study is to conduct a cost-benefit analysis of orientation and mobility (O&M) programs from three perspectives: the general public, the experienced, and the potential users of O&M programs.

METHODS

Willingness-to-pay (WTP) for O&M programs was collected via a contingent valuation survey using a double-bound dichotomous choice approach. WTP was estimated using interval regression analyses, accounting for study arm, sex, occupation, income, and self-rated health. The cost data were estimated from a service provider's perspective. The net present value (NPV), variation if delivered by tele-O&M, was investigated.

RESULTS

The adjusted mean NPV of O&M programs was $3857 (95% CI: $3760-$3954) per client, with highest NPV from the general public ($4289, 95% CI: $4185-$4392), followed by the experienced users ($3158, 95% CI: $2897-$3419) and the potential users ($2867, 95% CI: $2680-$3054). The NPV reached break-even for tele-O&M.

CONCLUSIONS

There was strong community support for investment into O&M programs considering benefits for clients over and above the cost of providing the services.Implications for rehabilitationThis study demonstrates the feasibility of using cost-benefit analysis with a contingent valuation approach to economically assess a rehabilitation intervention, where its multi-dimensional benefits cannot be fully captured by a conventional appraisal technique such as cost-effectiveness analysis.The high willingness-to-pay (WTP) values amongst the general public suggests that Australians perceive government's investment in orientation and mobility (O&M) rehabilitation as value for money and that individuals would be prepared to contribute to its costs.The lower WTP for O&M partially delivered via tele-practice (tele-O&M) indicates a lower acceptance of this innovation in comparison with the traditional face-to-face O&M.The estimated net present values of O&M programs, positive for traditional O&M and break-even for tele-O&M, can be of assistance to service planning and investment decisions within the Australian context.

The impact of low vision on social function: The potential importance of lost visual social cues

Visual cues usually play a vital role in social interaction. As well as being the primary cue for identifying other people, visual cues also provide crucial non-verbal social information via both facial expressions and body language. One consequence of vision loss is the need to rely on non-visual cues during social interaction. Although verbal cues can carry a significant amount of information, this information is often not available to an untrained listener. Here, we review the current literature examining potential ways that the loss of social information due to vision loss might impact social functioning. A large number of studies suggest that low vision and blindness is a risk factor for anxiety and depression. This relationship has been attributed to multiple factors, including anxiety about disease progression, and impairments to quality of life that include difficulties reading, and a lack of access to work and social activities. However, our review suggests a potential additional contributing factor to reduced quality of life that has been hitherto overlooked: blindness may make it more difficult to effectively engage in social interactions, due to a loss of visual information. The current literature suggests it might be worth considering training in voice discrimination and/or recognition when carrying out rehabilitative training in late blind individuals.

Binocular Integrated Visual Field Deficits Are Associated With Changes in Local Network Function in Primary Open-Angle Glaucoma: A Resting-State fMRI Study

In glaucoma participants, both structural and functional brain changes have been observed, but we still have insufficient understanding of how these changes also affect the integrity of cortical functional networks, and how these changes relate to visual function. This is relevant, as functional network integrity may affect the applicability of future treatments, as well as the options for rehabilitation or training. Here, we compare global and local functional connectivity in local and global brain networks between glaucoma and control participants. Moreover, we study the relationship between functional connectivity and visual field (VF) loss. For our study, 20 subjects with primary open-angle glaucoma (POAG) and 24 age-similar healthy participants were recruited to undergo an ophthalmic assessment followed by two resting-state (RS) (f)MRI scans. For each scan and for each group, the ROIs with eigenvector centrality (EC) values higher than the 95th percentile were considered the most central brain regions (“hubs”). Hubs for which we found a significant difference in EC in both scans between glaucoma and healthy participants were considered to provide evidence for network changes. In addition, we tested the notion that a brain region's hub function in POAG might relate to the severity of a participant's VF defect, irrespective of which eye contributed mostly to this. To determine this, for each participant, eye-independent scores were derived for: (1) sensitivity of the worse eye – indicating disease severity, (2) sensitivity of both eyes combined – with one eye potentially compensating for loss in the other, or (3) difference in eye sensitivity – potentially requiring additional network interactions. By correlating each of these VF scores and the EC values, we assessed whether VF defects could be associated with centrality alterations in POAG. Our results show that no functional connectivity disruptions were found at the global brain level in POAG participants. This indicates that in glaucoma global brain network communication is preserved. Furthermore, for the Lingual Gyrus, identified as a brain hub, we found a positive correlation between the EC value and the VF sensitivity of both eyes combined. The fact that reduced local network functioning is associated with reduced binocular VF sensitivity suggests the presence of local brain reorganization that has a bearing on functional visual abilities.

Physical Activity and Quality of Life in People With Visual Impairments: A Systematic Review

Objective

This systematic review aimed to investigate the relationship between physical activity and quality of life (QOL) in people with visual impairments. Methods: Electronic searches were performed in PubMed, SPORTdiscus, CINAHL, Embase, and Web of Science. Observational studies describing the relationship between physical activity and QOL in adults with visual impairments were included. The Newcastle-Ottawa Scale (NOS) adapted for cross-sectional studies was used to assess the quality of the studies. Results: Overall, 327 studies were identified, and eight met the inclusion criteria. All studies had cross-sectional designs and seven were performed in developed countries. Physical activity was assessed objectively by one study, and five studies used the International Physical Activity Questionnaire. The World Health Organization Quality of Life Questionnaire was the most used instrument to measure QOL. Six studies reported a positive relationship between physical activity and QOL domains, as follows: life satisfaction, activity limitation, fair or poor health, physically and mentally unhealthy days, psychological health, and overall QOL. Conclusion: People with visual impairments who are engaged in physical activity are more likely to have better QOL outcomes.

The link between blindness onset and audiospatial processing: testing audiomotor cues in acoustic virtual reality

Vision seems essential for cross-modal calibration of auditory cues in spatial perception. Previous findings showed that, in some specific tasks such as sound localization, blind individuals have enhanced skills, suggesting that the audiomotor loop might partially compensate for early visual loss in the calibration of auditory space; however, direct evidence is still lacking. Here, we proposed a method based on the alteration of the audiomotor loop. Acoustic virtual reality was used to measure the audiomotor loop's influence on the space perception of blind individuals. We developed a VR steering task by head or trunk pointing to auditory sources, where the audiomotor conflict is induced by letting trunk rotations change the auditory scene together with head rotations. Early blind, late blind, and sighted participants were tested to assess their sensitivity to the induced audiomotor conflict. The platform demonstrated its effectiveness in exposing participants' sensitivity to the audiomotor loop alteration. The early blind group was significantly more affected than the sighted group, while the late blind group did not significantly differ from any of the other groups. Our results confirm the increased role of the audiomotor loop for audiospatial information processing in blindness and advocate for the development of new spatial orientation training for blind people based on exploiting the audiomotor loop itself.

Population-Based Projection of Vision-Related Disability in Australia 2020 - 2060: Prevalence, Causes, Associated Factors and Demand for Orientation and Mobility Services

PURPOSE

To project the prevalence, causes, associated factors of vision-related disability and demand for orientation and mobility (O&M) services in Australia from 2020 to 2060.

METHODS

The age-specific prevalence and main causes of vision-related disability were estimated based on primary data of 74,862 participants in 2015 Survey of Disability, Ageing and Carers. Logistic regression analyses were performed to identify associated factors for the outcome variables including vision-related disability, cataract, macular degeneration and glaucoma. Future prevalence of vision-related disability and demand for O&M services were forecasted using the population projections by the Australian Bureau of Statistics through 2060.

RESULTS

The main causes of vision-related disability are non-specific sight loss, cataracts, macular degeneration and glaucoma. Health-related associations for vision-related disability are older age, having a history of stroke, having diabetes, depression, heart disease and hearing impairment. The number of Australians with vision-related disability (283,650, 1.10%) and demand for O&M services (123,317, 0.48%) in 2020 will increase to 559,161 (1.38%) and 237,694 (0.59%) respectively in 2060.

CONCLUSIONS

The number of people with vision-related disability and in need of O&M services in Australia will grow exponentially over the coming decades. General health promotion and specific strategies of early detection and timely treatments of the major eye diseases may ameliorate the trend in vision-related disability.

Environmental and behavioural interventions for reducing physical activity limitation and preventing falls in older people with visual impairment

BACKGROUND

Impairment of vision is associated with a decrease in activities of daily living. Avoidance of physical activity in older adults with visual impairment can lead to functional decline and is an important risk factor for falls. The rate of falls and fractures is higher in older people with visual impairment than in age-matched visually normal older people. Possible interventions to reduce activity restriction and prevent falls include environmental and behavioral interventions.

OBJECTIVES

We aimed to assess the effectiveness and safety of environmental and behavioral interventions in reducing physical activity limitation, preventing falls and improving quality of life amongst visually impaired older people.

SEARCH METHODS

We searched CENTRAL (including the Cochrane Eyes and Vision Trials Register) (Issue 2, 2020), Ovid MEDLINE, Embase and eight other databases to 4 February 2020, with no language restrictions.

SELECTION CRITERIA

Eligible studies were randomized controlled trials (RCTs) and quasi-randomized controlled trials (Q-RCTs) that compared environmental interventions, behavioral interventions or both, versus control (usual care or no intervention); or that compared different types of environmental or behavioral interventions. Eligible study populations were older people (aged 60 and over) with irreversible visual impairment, living in their own homes or in residential settings. To be eligible for inclusion, studies must have included a measure of physical activity or falls, the two primary outcomes of interest. Secondary outcomes included fear of falling, and quality of life.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included six RCTs (686 participants) conducted in five countries (Australia, Hungary, New Zealand, UK, US) with follow-up periods ranging from two to 12 months. Participants in these trials included older adults (mean age 80 years) and were mostly female (69%), with visual impairments of varying severity and underlying causes. Participants mostly lived in their homes and were physically independent. We classified all trials as having high risk of bias for masking of participants, and three trials as having high or unclear risk of bias for all other domains. The included trials evaluated various intervention strategies (e.g. an exercise program versus home safety modifications). Heterogeneity of study characteristics, including interventions and outcomes, (e.g. different fall measures), precluded any meta-analysis. Two trials compared the home safety modification by occupational therapists versus social/home visits. One trial (28 participants) reported physical activity at six months and showed no evidence of a difference in mean estimates between groups (step counts: mean difference (MD) = 321, 95% confidence interval (CI) -1981 to 2623; average walking time (minutes): MD 1.70, 95% CI -24.03 to 27.43; telephone questionnaire for self-reported physical activity: MD -3.68 scores, 95% CI -20.6 to 13.24; low-certainty of evidence for each outcome). Two trials reported the proportion of participants who fell at six months (risk ratio (RR) 0.76, 95% CI 0.38 to 1.51; 28 participants) and 12 months (RR 0.59, 95% CI 0.43 to 0.80, 196 participants) with low-certainty of evidence for each outcome. One trial (28 participants) reported fear of falling at six months, using the Short Falls Efficacy Scale-International, and found no evidence of a difference in mean estimates between groups (MD 2.55 scores, 95% CI -0.51 to 5.61; low-certainty of evidence). This trial also reported quality of life at six months using 12-Item Short Form Health Survey, and showed no evidence of a difference in mean estimates between groups (MD -3.14 scores, 95% CI -10.86 to 4.58; low-certainty of evidence). Five trials compared a behavioral intervention (exercise) versus usual activity or social/home visits. One trial (59 participants) assessed self-reported physical activity at six months and showed no evidence of a difference between groups (MD 9.10 scores, 95% CI -13.85 to 32.5; low-certainty of evidence). Three trials investigated different fall measures at six or 12 months, and found no evidence of a difference in effect estimates (RRs for proportion of fallers ranged from 0.54 (95% CI 0.29 to 1.01; 41 participants); to 0.93 (95% CI 0.61 to 1.39; 120 participants); low-certainty of evidence for each outcome). Three trials assessed the fear of falling using Short Falls Efficacy Scale-International or the Illinois Fear of Falling Measure from two to 12 months, and found no evidence of a difference in mean estimates between groups (the estimates ranged from -0.88 score (95% CI -2.72 to 0.96, 114 participants) to 1.00 score (95% CI -0.13 to 2.13; 59 participants); low-certainty of evidence). One trial (59 participants) assessed the European Quality of Life scale at six months (MD -0.15 score, 95% CI -0.29 to -0.01), and found no evidence of a clinical difference between groups (low-certainty of evidence).

AUTHORS' CONCLUSIONS

There is no evidence of effect for most of the environmental or behavioral interventions studied for reducing physical activity limitation and preventing falls in visually impaired older people. The certainty of evidence is generally low due to poor methodological quality and heterogeneous outcome measurements. Researchers should form a consensus to adopt standard ways of measuring physical activity and falls reliably in older people with visual impairments. Fall prevention trials should plan to use objectively measured or self-reported physical activity as outcome measures of reduced activity limitation. Future research should evaluate the acceptability and applicability of interventions, and use validated questionnaires to assess the adherence to rehabilitative strategies and performance during activities of daily living.

Mobility-Related Gaze Training in Individuals With Glaucoma: A Proof-of-Concept Study

Purpose

Older adults with glaucoma show inappropriate gaze strategies during routine mobility tasks. Furthermore, glaucoma is a risk factor for falling and colliding with objects when walking. However, effective interventions to rectify these strategies and prevent these adverse events are scarce. We designed a gaze training program with the goal of providing proof-of-concept that we could modify mobility-related gaze behavior in this population.

Methods

A total of 13 individuals with moderate glaucoma participated in this study. We taught participants general and task-specific gaze strategies over two 1-hour sessions. To determine the efficacy of this gaze training program, participants performed walking tasks that required accurate foot placement onto targets and circumventing obstacles before and after training. We used a mobile eye tracker to quantify gaze and a motion-capture system to quantify body movement.

Results

After training, we found changes in the timing between gaze shifts away from targets relative to stepping on them (P < 0.05). In the obstacle negotiation task, we found a greater range of gaze shifts early in walking trials and changes in the timing between gaze shifts away from obstacles after training (P < 0.05), each suggesting better route planning. A posttraining reduction in foot-placement error and obstacle collisions accompanied these changes (P < 0.05).

Conclusions

Our results demonstrated that it is possible to modify mobility-related gaze behavior and mobility performance in older adults with glaucoma.

Translational Relevance

This study provides proof-of-concept for a gaze training program for glaucoma. A larger, randomized controlled trial is warranted.

Optimising technology to measure functional vision, mobility and service outcomes for people with low vision or blindness: protocol for a prospective cohort study in Australia and Malaysia

INTRODUCTION

Orientation and mobility (O&M) specialists assess the functional vision and O&M skills of people with mobility problems, usually relating to low vision or blindness. There are numerous O&M assessment checklists but no measures that reduce qualitative assessment data to a single comparable score suitable for assessing any O&M client, of any age or ability, in any location. Functional measures are needed internationally to align O&M assessment practices, guide referrals, profile O&M clients, plan appropriate services and evaluate outcomes from O&M programmes (eg, long cane training), assistive technology (eg, hazard sensors) and medical interventions (eg, retinal implants). This study aims to validate two new measures of functional performance vision-related outcomes in orientation and mobility (VROOM) and orientation and mobility outcomes (OMO) in the context of ordinary O&M assessments in Australia, with cultural comparisons in Malaysia, also developing phone apps and online training to streamline professional assessment practices.

METHODS AND ANALYSIS

This multiphase observational study will employ embedded mixed methods with a qualitative/quantitative priority: corating functional vision and O&M during social inquiry. Australian O&M agencies (n=15) provide the sampling frame. O&M specialists will use quota sampling to generate cross-sectional assessment data (n=400) before investigating selected cohorts in outcome studies. Cultural relevance of the VROOM and OMO tools will be investigated in Malaysia, where the tools will inform the design of assistive devices and evaluate prototypes. Exploratory and confirmatory factor analysis, Rasch modelling, cluster analysis and analysis of variance will be undertaken along with descriptive analysis of measurement data. Qualitative findings will be used to interpret VROOM and OMO scores, filter statistically significant results, warrant their generalisability and identify additional relevant constructs that could also be measured.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Human Research Ethics Committee at Swinburne University (SHR Project 2016/316). Dissemination of results will be via agency reports, journal articles and conference presentations.

Revisiting Vision Rehabilitation

Low vision is a condition caused by eye or brain disease, in which visual acuity is 20/70 (3/10 or 6/18) or poorer in the better-seeing eye and cannot be corrected or improved with regular eyeglasses. It impacts personal ability to perform vision-dependent tasks as activities of daily living, walking, reading or using a computer. Rehabilitation is a multidisciplinary training dedicated to improve patients’ functional abilities and quality of life. It has to be personalized to every individual situation, whatever the underlying pathology.

A new primary mobility tool for the visually impaired: A white cane-adaptive mobility device hybrid

This article describes pilot testing of an adaptive mobility device-hybrid (AMD-H) combining properties of two primary mobility tools for people who are blind: the long cane and adaptive mobility devices (AMDs). The long cane is the primary mobility tool used by people who are blind and visually impaired for independent and safe mobility and AMDs are adaptive devices that are often lightweight frames approximately body width in lateral dimension that are simply pushed forward to clear the space in front of a person. The prototype cane built for this study had a wing apparatus that could be folded around the shaft of a cane but when unfolded, deployed two wheeled wings 25 cm (9.8 in) to each side of the canetip. This project explored drop-off and obstacle detection for 6 adults with visual impairment using the deployed AMD-H and a standard long cane. The AMD-H improved obstacle detection overall, and was most effective for the smallest obstacles (2 and 6 inch diameter). The AMD-H cut the average drop off threshold from 1.79 inches (4.55 cm) to .96 inches (2.44 cm). All participants showed a decrease in drop off detection threshold and an increase in detection rate (13.9% overall). For drop offs of 1 in (2.54 cm) and 3 in (7.62 cm), all participants showed large improvements with the AMD-H, ranging from 8.4 to 50%. The larger drop offs of 5 in (12.7 cm) and 7 in (17.8 cm) were well detected by both types of canes.

A Review of Cochrane Systematic Reviews of Interventions Relevant to Orthoptic Practice

AIM

To present an overview of the range of systematic reviews on intervention trials pertinent to orthoptic practice, produced by the Cochrane Eyes and Vision group (CEV).

METHODS

We searched the 2016 Cochrane Library database (31.03.2016) to identify completed reviews and protocols of direct relevance to orthoptic practice. These reviews are currently completed and published, available on www.thecochranelibrary.com (free to UK health employees) or via the CEV website (http://eyes.cochrane.org/) .

RESULTS

We found 27 completed CEV reviews across the topics of strabismus, amblyopia, refractive errors, and low vision. Seven completed CEV protocols addressed topics of strabismus, amblyopia, refractive errors, low vision, and screening. We found 3 completed Cochrane Stroke reviews addressing visual field loss, eye movement impairment, and age-related vision loss.

CONCLUSIONS

The systematic review process presents an important opportunity for any clinician to contribute to the establishment of reliable, evidence-based orthoptic practice. Each review has an abstract and plain language summary that many non-clinicians find useful, followed by a full copy of the review (background, objectives, methods, results, discussion) with a conclusion section that is divided into implications for practice and implications for research. The current reviews provide patients/parents/carers with information about various different conditions and treatment options, but also provide clinicians with a summary of the available evidence on interventions, to use as a guide for both clinical practice and future research planning. The reviews identified in this overview highlight the evidence available for effective interventions for strabismus, amblyopia, refractive errors, and low vision or stroke rehabilitation as well as the gaps in the evidence base. Thus, a demand exists for future robust, randomized, controlled trials of such interventions of importance in orthoptic practice.

Does walking speed mediate the association between visual impairment and self-report of mobility disability? The Salisbury Eye Evaluation Study

OBJECTIVES

To determine whether performance speeds mediate the association between visual impairment and self-reported mobility disability over an 8-year period.

DESIGN

Longitudinal analysis.

SETTING

Salisbury, Maryland.

PARTICIPANTS

Salisbury Eye Evaluation Study participants aged 65 and older (N=2,520).

MEASUREMENTS

Visual impairment was defined as best-corrected visual acuity worse than 20/40 in the better-seeing eye or visual field less than 20°. Self-reported mobility disability on three tasks was assessed: walking up stairs, walking down stairs, and walking 150 feet. Performance speed on three similar tasks was measured: walking up steps (steps/s), walking down steps (steps/s), and walking 4 m (m/s).

RESULTS

For each year of observation, the odds of reporting mobility disability was significantly greater for participants who were visually impaired (VI) than for those who were not (NVI) (odds ratio (OR) difficulty walking up steps=1.58, 95% confidence interval (CI)=1.32-1.89; OR difficulty walking down steps=1.90, 95% CI=1.59-2.28; OR difficulty walking 150 feet=2.11, 95% CI=1.77-2.51). Once performance speed on a similar mobility task was included in the models, VI participants were no longer more likely to report mobility disability than those who were NVI (OR difficulty walking up steps=0.84, 95% CI=0.65-1.11; OR difficulty walking down steps=0.96, 95% CI=0.74-1.24; OR difficulty walking 150 feet=1.22, 95% CI=0.98-1.50).

CONCLUSION

Slower performance speed in VI individuals largely accounted for the difference in the odds of reporting mobility disability, suggesting that VI older adults walk slower and are therefore more likely to report mobility disability than those who are NVI. Improving mobility performance in older adults with visual impairment may minimize the perception of mobility disability.

Current methods of visual rehabilitation

BACKGROUND

Despite therapeutic progress, many diseases of the eyes and visual pathways still cause persistent visual deficits that make everyday life more difficult in many ways. Rehabilitation aims to compensate for these limitations by optimizing residual vision. The demand for visual rehabilitation will increase markedly in the near future.

METHODS

We summarize the state of the art in visual rehabilitation on the basis of a selective review of the literature, including randomized, controlled trials (RCTs) in the Cochrane and PubMed databases as well as Cochrane reviews. We also pay particular attention to studies illustrating an important principle or a clinically established method.

RESULTS

Central visual field defects impair reading. Persons with an absolute central scotoma can regain reading ability by eccentric fixation and text magnification. Many kinds of magnifying visual aids are available. Specific reading training can further improve reading speed. Peripheral field defects impair orientation. Persons with a concentric field defect can be helped by tactile aids, such as a cane, and with orientation and mobility training. Persons with hemianopia can benefit from compensatory saccadic training.

CONCLUSION

Suitable rehabilitative measures chosen after the thorough diagnostic evaluation of a visual impairment and analysis of its effects can usually restore reading ability, improve orientation, and thereby enhance the patient's independence and quality of life. As the demand for visual rehabilitation is increasing, steps will need to be taken to make it more widely available. Furthermore, as the scientific basis for visual rehabilitation is currently inadequate in some areas, more research in the field will be needed.