This literature review explores factors related to the adoption of vision rehabilitation strategies in different service delivery and financing models. The scientific evidence on effectiveness of rehabilitation services for patients with vision impairments is examined in a broader context of rehabilitation for chronic impairments. This review was prepared for the Agency for Healthcare Research and Quality by The Lewin Group.
Introduction
Methods
General Rehabilitation
General Framework
Evidence for Effectiveness of Rehabilitation in General
Evidence for Rehabilitation of Specific Disabilities
Vision Rehabilitation
Definition of Vision Impairment and Goals of Vision Rehabilitation
Applying the Framework to Vision Rehabilitation
Populations Affected
Types of Vision Rehabilitation Interventions
Models of Delivery
Adoption of Services
Conclusion
References
Appendix: Disability Primer
Definition of Disability and Goals of Rehabilitation
Populations Affected
Types of Interventions
Models of Rehabilitation Delivery
There is a growing need for public and private health and social services programs to serve people with disabilities. Rehabilitation services may include medical or surgical therapy, environmental measures, or social and financial support services to improve the physical or social functioning of the disabled person. Rehabilitation for disabled persons also addresses access to primary health care services. Comprehensive care is increasingly recognized as necessary to meet the needs of the disabled. Disabled persons are overrepresented in populations that have been traditionally underserved due to low socioeconomic status, racial and ethnic minority status, and limited geographic proximity to care.
The Agency for Healthcare Research and Quality (AHRQ) commissioned The Lewin Group to study rehabilitation of people with vision impairments and to explore factors related to the adoption of vision rehabilitation strategies within different models of service delivery and financing. This study reviews and synthesizes the scientific literature regarding the effectiveness of rehabilitation services for patients with vision impairments within the broader context of rehabilitation for chronic impairments.
It is estimated that 54 million Americans, or nearly 20 percent of the population, currently live with disabilities,1 and vision impairment is 1 of the 10 most frequent causes of disability in America.2 Estimates of the number of Americans with low vision vary. According to the Baltimore Eye Study, an estimated 3 million people have low vision, 1.1 million are legally blind, and 200,000 are more severely visually impaired.3 When low vision is more broadly defined to include visual problems that hamper the performance and enjoyment of everyday activities, almost 14 million Americans are estimated to have low vision.4
The leading causes of visual impairment are diabetic retinopathy, cataract, glaucoma, and age-related macular degeneration (AMD). There is a significant concentration of vision impairment in the older adult population: more than two-thirds of visually impaired adults are aged 65 years or older. Because the older adult population is the fastest growing age group, it is estimated that the number of people with visual impairment will increase. Further, as the prevalence and incidence of diabetes increases, particularly among those younger than 65, more people are at risk for developing vision impairment due to glaucoma or diabetic retinopathy.5
A variety of factors may hinder the rate and success of the adoption and use of rehabilitation strategies. There is inadequate investment in rehabilitation research, limiting the amount and quality of research being conducted. Rehabilitation research findings often are not widely distributed or published in mainstream journals. Further, there is only very limited research on the cost-effectiveness of rehabilitation services. As a result, it can be difficult for health care providers and other decisionmakers within different models of care to approve the adoption of particular strategies.
Recently, increasing attention has been paid to the funding of vision rehabilitation services. The Senate FY 2000 Appropriations Committee bill, from which this project originated, included several measures which funded initiatives related to vision and vision rehabilitation. The bill recognized the success of the Alaska Council for Independent Living, stating that independent living centers are effective and cost-saving.a In addition, the Medicare Vision Rehabilitation Coverage Act of 1999 (H.R. 2870) and Medicare Vision Rehabilitation Services Act of 2001 (H.R. 2484) were introduced to provide Medicare reimbursement for vision rehabilitation services provided by physicians, occupational therapists, or vision rehabilitation professionals as physician extenders. These Medicare proposals may heighten attention paid to research regarding the effectiveness of services.
a Independent living centers provide services to older blind individuals, which may include the provision of eyeglasses and other visual aids, mobility training, Braille instruction and training in other communication devices, community integration, and information and referral.
Lewin conducted a search of recent scientific literature on issues relevant to general and vision specific rehabilitation. We identified relevant articles through a search of the National Library of Medicine database MEDLINE®, using combinations of such MeSH search terms and key words as: Rehabilitation, Disabled Persons, Delivery of Health Care, Vision, and Technology. In addition to the MEDLINE® database, 29 other medicine and health related bibliographic databases were searched. These included SciSearch®, HealthSTAR, EMBASE®, and Science, among others. The following search terms were used: Rehabilitation, Disability, Vision, Technology, Social Services, and Evidence, among others. In addition, project abstracts of work funded by the National Institute on Disability and Rehabilitation Research (NIDRR), available from the National Rehabilitation Information Center (NARIC), were searched for relevant studies. We also searched the Internet for professional association reports and practice guidelines. In addition, Lighthouse International, a private agency serving the visually impaired, was a source of information.
Expert advisors to this project identified additional relevant materials, including research published in journals not indexed by MEDLINE®, as well as books and unpublished research. For example, expert-maintained bibliographies of the literature in the field of vision impairment were searched for relevant articles. Given the emerging state of the evidence base, experts were helpful in framing the issues within the field and describing common practices. In addition, the experts' input ensured that no bodies of literature had been missed. This was particularly helpful to identify articles in journals not indexed by MEDLINE® or the other databases searched.
Literature identifying general models of rehabilitation care for people with disabilities is sparse. Therefore, we explored literature, evidence reports, and practice guidelines for information on rehabilitation for certain of the most studied diseases, including traumatic brain injury, stroke, and myocardial infarction, in an effort to draw common themes. We developed a framework to aid in analyzing the literature, as described in the next section.
The Lewin Group constructed a rehabilitation framework for this project in order to characterize and categorize rehabilitation services (Figure 1, 24 KB). This framework builds on the existing models for rehabilitation of the World Health Organization (WHO) and others, but places greater emphasis on relating the nature of impairment to the corresponding nature of care, i.e., levels or types of services as well as their sites of delivery, as described below.
The framework is arranged in rows by level of one's experience or interaction that is affected by the disability, and in columns by stage of condition, services delivered, and context for service delivery, as follows.
The entries along each row and column are not necessarily distinct or exclusive, but represent ranges of attributes that can be used to describe the need for, delivery of, and other aspects of rehabilitation services. For example, the sites of service do not necessarily align one-to-one with the stages of condition.
An advantage to this framework is that it can help direct and organize the findings of a literature synthesis on rehabilitation in a way that reflects how care for particular types of impairment is delivered and by what means it is paid, since these tend to be defined by service type and delivery setting. As such, this is more of an empirical, rather than a normative, framework. The utility of this framework could be evaluated by how well it helps to identify gaps in care or lack of continuity of care for patients, including particular policies and practices (e.g., payment policies or professional jurisdictions) that act as barriers or disincentives to optimal care.
The framework illustrated with the example of stroke rehabilitation is presented in Figure 2 (24 KB).
The "stage" column in the framework shows that physiological changes resulting from an underlying disease or injury may lead to impairment, which in turn may result in disability or handicap. In the instance of stroke, brain tissue is damaged from a lack of blood flow, which may lead to a limitation in normal functioning ability, e.g., memory loss or limited mobility. These impairments may result in a disability or handicap that constrains the individual's normal social role, e.g., by limiting capacity to work. (This literature review does not distinguish between the terms "disability" and "handicap," although some literature does.)
The "services" column of the framework shows that services differ according to the stage of the disabling condition. Continuing with the example of stroke, anticoagulant drugs may be administered to break up blood clots. Impairment may be addressed through such services as cognitive skills training for memory loss or use of a walker of physical therapy for limited mobility. In order to help maintain the individual's social role and functioning in the community, programs such as "Meals on Wheels" or technological adaptations in the workplace can address the disability.
The "context for services" column of the framework shows that rehabilitation services are provided in different settings and by different providers, corresponding to the stage of the disabling condition and type of services needed. For example, a stroke victim may initially present to the emergency room and be admitted to the hospital to be administered anticoagulants under supervision of a physician. As such, rehabilitation would differ little from medical intervention. Services to address the impairments of stroke may be delivered in a rehabilitation stroke unit of a hospital or in a residential nursing home, skilled nursing facility, or on an outpatient basis. Services to address the individual's social role are provided on an outpatient basis, and might include for example environmental modifications and transportation services.
It is notable that throughout health care, the context for service delivery has shifted; inpatient hospital stays are shorter as patients are managed in less intensive settings, moving from inpatient care to rehabilitative hospitals, skilled nursing facilities, or outpatient care. The growth of managed care and prospective capitated payment for inpatient health care has provided incentives to shift care from inpatient to outpatient settings, contributing to the increase in services provided in skilled nursing facilities, other ambulatory settings, and the home.6
Randomized controlled trials (RCTs) and other rigorous types of experimental designs tend to be difficult to conduct for various types of rehabilitation. Aside from the few types of more common and medically-oriented rehabilitation (such as for stroke and trauma), it is difficult to control for multiple factors that may confound study results, such as the presence of comorbidities, differences in physical home environments, and varying availability of caregiver support. Because population groups with particular types of rehabilitation needs may be small as well as diverse, it is difficult to accrue sufficiently large numbers of individuals into RCTs so that potentially confounding factors would be evenly distributed between an intervention group and a control group. Further, whereas research funding in the larger health care system facilitates and motivates the identification of potential enrollees for clinical trials, the more diffuse and less coordinated system encompassing much of rehabilitation is not as able to identify potential enrollees. Measurement of outcomes across the continuum of care, i.e., for the multiple types and sites of service that may be involved in rehabilitation, is particularly challenging and not well developed to date.7 Despite these challenges, rehabilitation has started to become a more evidence-based specialty.8 Investigators call for an increase in systematic technology assessment of devices, drugs, and services used in rehabilitation.9,10
In the absence of adequate evidence on the effectiveness of rehabilitation interventions in general, it is instructive to examine the evidence for the effectiveness of rehabilitation interventions for selected disabilities. We examined the evidence for the effectiveness of rehabilitation for traumatic brain injury, stroke, and myocardial infarction, which represent a significant proportion of the activity and aggregate costs of rehabilitation services. Further, they illustrate the range in magnitude and strength of evidence associated with rehabilitation interventions and some of the uncertainty inherent in applying unproven and equivocal interventions more widely.
Traumatic Brain Injury
In 1999, AHRQ published an evidence report conducted by the Oregon Health Sciences University on rehabilitation for traumatic brain injury in adults.11 (Select for Summary.) This study examined available evidence on the effectiveness of:
The report found that there is weak evidence to support the association of early rehabilitation with a shorter inpatient rehabilitation length of stay. Further, there is a lack of evidence regarding the association between therapeutic intensity (measured as hours of treatment) and beneficial effects of acute inpatient traumatic brain injury rehabilitation. Associations between cognitive rehabilitation and outcomes were inconsistent. The report did find that well-done, prospective observational studies support the use of supported employment within the context of well-designed, well-coordinated programs. Finally, there was no clear evidence about the effectiveness of case management for traumatic brain injury survivors.
The results of this systematic review indicate that the evidence supporting the effectiveness of inpatient rehabilitation is weak for traumatic brain injury. The evidence report recommended that population-based studies with adequate controls be conducted to examine the overall impact of traumatic brain injury and the differences in outcomes associated with different rehabilitation strategies. It is important to emphasize that the report cited a lack of evidence of benefit for certain interventions, as opposed to evidence of no benefit. Even while the benefits of various approaches remain unclear, most professionals concur that rehabilitation is an appropriate course of treatment. As asserted by the authors of this evidence report, "in the presence of a need for treatment and the absence of clearly superior alternatives, choices must be made between therapies without proven superiority over others based on clinical pragmatism." However, general professional agreement regarding the effectiveness of rehabilitation interventions in the absence of more rigorous evidence is likely to be insufficient for establishing and maintaining high-quality rehabilitation services or consistent and adequate payment for these services.
AHRQ published a similar systematic review conducted by the Oregon Health Sciences University of rehabilitation for traumatic brain injury in children and adolescents.12 (Select for Summary.) This report found that the relevant published literature is primarily exploratory and, in general, studies have not been conducted with designs capable of providing evidence on the effectiveness of interventions for children and adolescents with traumatic brain injury.
Stroke
An acute stroke episode may result in a variety of disabilities or conditions, such as motor impairment, dysphagia (swallowing impairment), and memory loss. These conditions call for different types of rehabilitation that are generally not provided by a single type of clinician or in a single type of setting. During the course of stroke rehabilitation, care may be provided across multiple settings, depending on the patient's medical stability, physical endurance, degree of functional impairment, and home support available. The literature suggests that, in general, a multidisciplinary approach is better in terms of outcomes, systematic approaches are more effective than non-systematic approaches, and community-based rehabilitation support leading to early discharge can reduce length of stay for some patients.7
A systematic review of 19 RCTs comparing specialist inpatient stroke care with conventional care (i.e., in a general medical ward) concluded that organized stroke unit care resulted in long-term reductions in death, dependency, and the need for institutional care.13 Factors that may have contributed to these positive effects of stroke unit care include:
This analysis may have implications for rehabilitation services for other disabling disorders, including that coordinated, specialized rehabilitative care may be more effective than general medical care for these other types of rehabilitation. However, the generalizability of these findings should be confirmed with further research.
The evidence base of specific interventions in stroke rehabilitation is less clear. The Cochrane Collaboration recently concluded that there is insufficient evidence in the form of controlled trials to support or refute the effectiveness of cognitive rehabilitation for memory problems after stroke.14 Similarly, another Cochrane review concluded that the use of cognitive rehabilitation for attention deficits to improve functional independence following stroke is neither supported nor refuted by the available evidence.15 The Cochrane Collaboration also found that speech and language therapy treatment for people with aphasia (communication impairment) after a stroke has not been shown to be either clearly effective or clearly ineffective within an RCT.16 As suggested by White and Johnstone, the medical model of stroke rehabilitation may place undue emphasis on clinical diagnosis and treatment, with measurement of physical independence and disability reduced to standard scales, "to the neglect of the emotional and social consequences of stroke and a partial or inhibited view of the person."17 As in the case of rehabilitation for traumatic brain injury, despite less than concrete evidence, experts generally agree that stroke patients derive benefit from rehabilitation. Notwithstanding this general consensus, further research is needed to confirm the effectiveness of various specific rehabilitative interventions for stroke care.
Myocardial Infarction
Cardiac rehabilitation aims to restore patients who have suffered myocardial infarction to optimal health, whether through exercise-only based rehabilitation or comprehensive rehabilitation involving some combination of, e.g., smoking cessation, improved nutrition, and exercise. Multiple RCTs have been conducted of cardiac rehabilitation, showing it to be safe and effective. Comprehensive programs appear to be more effective than single interventions.7 A recent systematic review by the Cochrane Collaboration of randomized clinical trials involving a total more of than 7,000 patients examined evidence on the effectiveness of rehabilitation compared to usual care.18 The review concluded that exercise-based cardiac rehabilitation appears to be effective in reducing cardiac deaths. However, it noted that the evidence base consists primarily of poorly designed studies.
Findings regarding the evidence for rehabilitation for traumatic brain injury, stroke, and myocardial infarction are instructive for vision rehabilitation. These three highly prevalent types of rehabilitation are:
Despite these factors, the evidence bases in support of their effectiveness tend to be weak in today's context of evidence-based health care. Certainly, more research is needed to determine the clinical effectiveness of these forms of rehabilitation. While there is a trend toward the use of multidisciplinary care, particularly for stroke, and some evidence for its effectiveness, there remain weaknesses in evidence for both multidisciplinary approaches and for specific rehabilitation interventions. In contrast, vision rehabilitation is more often linked with chronic, longer term conditions, is far less integrated with physician practice and mainstream health care, and is consequently far less subject to third-party payment.19 These factors have tended to diminish the demand for evidence for the effectiveness of vision rehabilitation. Also, while there is a trend toward multidisciplinary care for vision rehabilitation, there is, as in other forms of rehabilitation, only limited evidence for its effectiveness.
The literature offers several definitions of vision impairment. Low vision is defined as a visual impairment severe enough to interfere with successful performance of activities of daily living (ADLs) although some usable vision is retained.20 The WHO offers the following definitions of low vision, using standard measures of visual acuity and field diameter:21
bLargest field diameter for Goldmann isopter III4e, 1/100 white test object or equivalent.
The categorization of visually impaired persons into a legally blind/legally sighted dichotomy may inappropriately limit access to public benefits.22 Some who fall under the diagnostic category of legally blind could function highly, while others who are categorized as legally sighted could have a greater need for services because of comorbidities or socioeconomic or other factors. Therefore, those with the greatest need for services may not be eligible for public benefits because they do not meet diagnostic criteria.
Low vision can result from a variety of ophthalmologic and neurologic disorders. The most common causes of low vision in the United States include:
In addition, a number of other diseases, such as stroke, head injury, or tumors may result in conditions such as field cuts or visual neglect, in which individuals never see a certain portion of the visual field or in which the brain does not perceive half the visual world (i.e., a person with left visual neglect will not even be aware that they are unable to see the left side of the world).
Vision rehabilitation usually encompasses services such as adaptive equipment, skills training, and social support for individuals whose visual impairment cannot be satisfactorily addressed through corrective lenses, medication, or surgery. While preventive interventions fall outside the focus of this review, it is important to note that some vision loss can be prevented. Drug therapy and surgical procedures may help in preventing vision loss or stopping the progression of diseases such as glaucoma, diabetic retinopathy and age-related macular degeneration.
Early detection and treatment can prevent up to 90 percent of cases of diabetes-related blindness. Treatments for diabetic retinopathy include laser surgery (photocoagulation) and standard surgery (vitrectomy). Treatments to slow the progression of glaucoma are available and include medications, laser surgery, standard surgery, and drainage implant devices.4,23 Many people could benefit from laser surgery but do not get it.24 Medical treatment for glaucoma is available, but drugs are costly, must be taken for life, and have side effects although newer glaucoma drugs are associated with reduced side effects.25 Glaucoma treatments are only effective when the disease is detected early (through a dilated eye exam). It is estimated that half of Americans with glaucoma are unaware that they have the condition.24 Although there is no evidence for effective treatments for most individuals with AMD, experimental and investigational treatments are available (e.g., submacular surgery, external-beam radiation therapy, and thalidomide) and basic research is currently being conducted in a number of promising areas (e.g., retinal transplantation, electronic retinal prosthesis, and gene therapy). However, as noted earlier, vision that is lost cannot be restored with currently available treatments.
The overall goal of vision rehabilitation is to "recapture, strengthen and maintain self-confidence for safe, independent functioning".21 The American Academy of Ophthalmology (AAO) states that rehabilitation training teaches individuals how to best use their remaining sight and provides patients with practical adaptations for ADLs. AAO states that vision rehabilitation is more effective if it is started as soon as functional difficulties are identified.21
One of the more specific goals of vision rehabilitation is improved functional independence through training in orientation and mobility. Areas of orientation and mobility assessment may include indoor travel, public indoor travel, outdoor travel, and public transportation. For example, curricula in orientation and mobility travel skills are determined based on individual needs, abilities, and limitations, but can include development of orientation skills, development of language skills, concept development, sensory development, development and understanding of functional vision, if any, learning a system for movement, and identification of resources.26
Reading is one of the instrumental or basic ADLs that is most affected by vision loss. Because reading is so integral to communication, it is often targeted as a goal of vision rehabilitation.27 Activities that are commonly affected by low vision include the following:27,28,29
Vision rehabilitation plans are created following a functional assessment of ADL skills. The individualized written rehabilitation plan may specify the client's goals for improving performance, the skills to be addressed, and how long the instruction is expected to take place.27,28