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Chapter 2 THE DEMOGRAPHY OF BLIND AND VISUALLY IMPAIRED PEDESTRIANS To meet the needs of visually impaired and blind people by building more effective mobility aids, it is important to get a better sense of the size and characteristics of the population to be served. Such information would be helpful not only for service delivery but also for the design and development of travel aids that more closely match the population needs and the patterns of use and nonuse among these indi- viduals. This chapter reviews the definitions of visual impairment that are used for purposes of demographic analysis, reports findings from available statistics about the number and characteristics of the visually impaired population, and describes what is known about the patterns of use of travel aids today. The chapter concludes with recommendations for further work to improve our understanding of demographic characteristics relevant to the mobility needs of visually impaired and blind people. SOME DEFINITIONS In disability-related research and policy generally, some common definitions have been developed to describe all types of impairment. Athough terminology may vary, agreement has emerged around a set of four concepts: pathology, impairment, disability, and handicap. Briefly defined, pathology refers to a medically determined disease or disorder (including trauma, structural abnormality, etch. Impair- ment refers to lasting consequences of pathology, affecting parts of the organism. Disability refers to limitations in carrying out tasks. At this level of analysis, the individual and inevitably such factors as motivation, training, and the resources {aids) available to help accomplish tasks are involved. Handicap refers to limitations in performing social roles (socially structured sets of tasks). At this level, the characteristics of the The studies that are the basis for this consensus include reports by the Social Security Administration, the World Health Organization, and the Office of Technology Assessment. 10

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11 social environment, including socioeconomic resources, discrimination, and characteristics of the individual, are involved. Whatever criteria are used to identify the population of visually impaired people in the United States, there are several ways to classify subgroups of that population in relation to their probable use or nonuse of mobility aids. The size and demographic characteristics of that population will presumably be different depending on which of the con- cepts is under study. There are also likely to be varying degrees of overlap among the groups defined in this way. Our focus in this report is on disability--i.e., the limitations of visually impaired people in carrying out the tasks of mobility. Demographic information about the visually impaired population in terms of pathology, impairment, and handicap is important mainly in terms of its relevance to mobility tasks. Unfortunately, available statistics on the blind population are grossly inadequate. We are forced to make estimates that may be out of date or unrepresentative as well as not focused on the most pertinent determinants of disability. Psychosocial factors, such as access to support groups and rehabilitation services and income level, are important predictors of disability for which there are few available data. The measure that is most readily available to draw a demographic profile, legal blindness, suffers in that it does not address many relevant factors that contribute to disability. Legal blindness is defined in terms of two aspects of visual impairment, acuity and field size (i.e., acuity of 20/200 or worse in the better eye with correction or a visual field of 20 degrees diameter or less). It does not take into account other visual factors, such as sensitivity to glare or light and dark adaptation, that also affect mobility and other visual tasks. Specific types or degrees of impairment reveal very little about disability for any individual person. Very often two people with identical impairments have markedly different disabilities. The field of nonmedical rehabilitation, in fact, aims to reduce the disabilities associated with given impairment and justify the need for individual rehabilitation plans. Although the estimates have many limitations, we use statistics on the prevalence, incidence, and demographic charac- teristics of legal blindness in the United States in the next section to describe the legally blind population. DEMOGRAPH I C CHARACTER I S T I C S It is possible to estimate the number of legally blind people--the prevalence of blindness--in the United States today using the Bureau of the Census projections of the population and the estimated prevalence rates. The prevalence rates published in Vision Problems in the United States (National Society to Prevent Blindness, 1980) and the projected population for the years 1985 and 2000 are presented in Table 1. These prevalence rates are generally believed to be underestimates of the true rates and unrepresentative, since they are based on limited sampling plans or registries that are out of date. In addition, survey defini-

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13 tions may exclude some people with low vision (i.e., having a visual impairment that affects mobility but who are not legally blind), thus contributing to an underestimation of the population of interest. These sources remain, however, the best estimates available today. For large groups of people who share the same category of impair- ment, it is possible to draw some inferences about disability and the presence of mobility problems in a probabilistic sense, even though the prediction will not be valid for all individuals in the group. There- fore it is important to examine the characteristics of the legally blind population that might be useful in making inferences about disability: age, age at onset, degree of impairment, other impairments, and social factors. Age The number of cases of blindness for different age categories can be calculated by multiplying the prevalence rate times the population count for each age category. That calculation or estimate is shown for the years 1985 and 2000 in Table 1. The prevalence of blindness in the population is greatest in the older age categories. This is in part due to the simple accumulation of incidence with age, but this alone cannot explain the large increase in prevalence in the oldest age categories. Figure 1 shows the 1985 estimates plotted as percentages by age groups. For example, the age group 20-44 is almost 40 percent of the population, yet it constitutes only 17.5 percent of the blind population. The age group 75-84 con- stitutes approximately 4 percent of the population in the United States and 24 percent of the blind population. More than half the blind people in the United States today are over the age of 64. This can be seen graphically by plotting the ratio of the percentage of blind people in each age group to the percentage of people in the U.S. population in the same age group (Figure 2~. People under the age of 45 are underrepresented in the blind population, whereas people in the 85 and older group are overrepresented in the blind population by better than a factor of 12. The U.S. population is aging. The median age increases each year-- or, put differently, the relative proportion of people in the older age groups is on the rise. By the year 2000, it is predicted that the U.S. population will increase by 12 percent, yet the blind population will increase by 29 percent. This prediction assumes constant rates of prevalence; thus, all the disproportionate increase is due to the aging phenomenon in the U.S. population. The assumption of constant rates could lead to inaccurate estimates if, for example, there occur improvements in eye care and the prevention and treatment of eye problems or, conversely, greater incidence of impairment. Although over half of all blind people are over the age of 64, there remains a large and significant group of people who are blind before the age of 20, approximately 7 percent, and an even larger group who are blind before the age of 45, approximately 24 percent. For

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14 50 40 Z 30 Cal G 20 10 APopulabon (19~) - ., 1 r' , , , , egal Blindness (1985) _ ~ 0~4 5-19 20~44 45~64 65-74 75-84 85+ AGE CATEGORIES FIGURE 1 Distribution of legal blindness in the general population by age group, 1985e 12 10 Zii~ O o F zg 8 C) ~ Zen 6 Z Z LU ~ O.O to lo: 4 ~ 1m CL ~ 2 I / I . I r I I I I 0~4 5-19 20-44 45-64 65-74 75-84 85+ AGE CATEGORIES FIGURE 2 Ratio of percentage of blind people to the percentage of people in U.S. population by age group, 1985.

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15 these individuals, blindness is a condition of life during the period in which they are likely to be most economically productive. Onset of Visual Problems The age at which impairment occurs is an important factor. The usual classifications distinguish between those who are blind from birth or at less than five years of age--congenital blindness--and those who have lost sight at older ages--adventitious blindness. The key to this distinction is the role that early visual experience plays in establishing spatial concepts and visual memories, which later aid functioning when visual impairments reduce or eliminate the ability to see. Table 2 presents the incidence of legal blindness--i.e., new cases of legal blindness by age and etiology published in Vision Problems in the United States as estimated for the year 1978. The rate of incidence in the population is roughly stable at O.01 percent until the age of 45; it then increases for each age group, achieving its highest rate, 0.27 percent, for the 85 and older age group. The distribution of etiologies within age groups changes with age. For example, the most frequent causes of blindness under the age of 20 are infectious diseases, injuries, and prenatal influences. After the age of 44 the major causes are chronic diseases such as diabetes and macular degeneration. Visual loss has several dimensions: the age at onset, the end point or eventual level of loss, and the rate of progress to reach the end point. Each of these dimensions may affect a person's mobility rehabilitation program. Many authors have proposed phases through which an individual progresses from the onset of a disability. There is general agreement that some internal or psychological adjustments should occur prior to entering a mobility program for the-disabled person to obtain maximum benefits. Rehabilitation professionals have observed that individuals with slowly progressing loss of vision, such as retinitis pigmentosa (RP), tend to have a difficult time accepting mobility aids because of the stigma imposed by the aid and the lack of a specific timetable for when their vision will decrease. There often seems to be a hope that either the condition will not progress or that a cure will be found. Entering into a rehabilitation program and using a mobility aid seem to conflict with this hope and often severely affect the person's acceptance of mobility instruction. This type of individual can be contrasted to those who have a fixed loss with remaining vision (macular degenera- tion), who can be told that the condition will not progress to total blindness. Once the condition has stabilized r mobility instruction and the use of mobility aids are generally quite successful. A characteristic of some RP patients is a slow adaptation to changes in light level. A transient problem of this sort may call for special devices to aid mobility during this transitory state.

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16 TABLE 2 New Cases of Legal Blindness (Incidence) According to Etiology in the United States, 1978 (numbers in thousands) 0-5 5-19 20-44 45-64 65-74 75-84 85+ Total I nf ectious diseases 200 100 200 250 50 50 Injuries/ poisonings 200 350 Neoplasms 100 150 General diseases 50 100 1,050 Prenatal influence 800 2, 250 Unknown or 150 650 unspecif fed Multiple etiologies Total As Percentage of Population: -- 850 500 400 100 50 50 1, 650 100 100 -a - 450 4,700 4,300 6,700 3,900 20,800 1,500 1,150 300 1,750 3,600 2,550 -- 50 100 1,500 3,650 5,200 200 -- 6,200 3,000 1,150 15,850 650 850 1,350 800 3,800 10,850 8,150 11,350 5,900 46,600 .01 .01 .01 .02 .05 .16 .27 .02 SOURCE: National Society to Prevent Blindness { 1980) .

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17 Degree of Visual Impairment The legally blind population can be partitioned into those people who are "totally blind," in the sense that they have no sensitivity to light, and those with some sensitivity to light. It is obvious that the lower boundary of useful vision may be defined variously for various tasks and for different situations such as twilight or darkness. It is less obvious, but also true, that there is room for debate about the upper boundary of total blindness as well. For example, the category of "total blindness" is sometimes grouped with vision measured as n light perception only" to form the category oF nno useful vision," but it is disputable whether light perception does provide useful informa- tion. Although there have been some efforts to partition this category further (Colenbrander and Spivey, 1976), there is a need to determine whether the proposed categories are functionally related to differences in accomplishing mobility tasks. 2 It is highly probable that different levels of disability affect the choice of mobility aids or the way in which they are used. For example, two broad categories of visual loss, reduced acuity and reduced visual field, present very different functional difficulties. Therefore, it is reasonable to expect that the possible use of mobility aids will vary depending on the type and severity of visual disability. Table 3 shows the prevalence (total number of cases in the population) and incidence (number of new cases added each year) of legal blindness by degree of impairment in terms of number of cases and percentages estimated for the year 1978 based on the data reported in Vision Problems in the United States. The rate of both prevalence and incidence increase for all impairment categories with age. Roughly 20 percent of the legally blind could be categorized as having "no useful vision" (by adding together the categories of "total blindness" and 2Levels of blindness and visual impairment have been proposed for planning individual rehabilitation programs, travel capability, legal status, tax exemption, supplemental social security awards, and the like: I. Blindness: 1. No light perception (total blindness) 2. Light perception and crude form recognition 3. Gross pattern recognition (light-assisted orientation) II. Low Vision: Best vision in better eye with conventional glasses or contact lenses to approximately 20/200 or 20/200 with gross field defects. Approximately 20/100 - 20/70 with or without field defects. III. Partial Vision: 1. Approximately 20/60 or better: uses approach magnification and simple magnifier.

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18 TABLE 3 Prevalence and Incidence of Legal Blindness by Level of Impairment in the United States, 1978 Prevalence Incidence - Number Percent Number Percent Totally blind 52,300 11 3,100 7 Light perception 57,200 11 4,200 9 Light projection 5,600 1 450 1 Less than 5/200 81,450 16 7,200 15 5/200 to 10/200 49,200 10 5,800 12 10/200 to 20/200 78,950 16 7,200 15 20/200 111,200 23 1,250 27 Restricted field 35,450 8 4,050 9 Unknown 26,650 6 2,100 5 SOURCE: National Society to Prevent Blindness (1980~. "light perceptions), and 15 percent of new cases fall into this group Most experts believe that the 20/200 category is overstated because many physicians do not attempt to determine the full extent of visual impairment once they have determined that an individual is legally blind (e.g., 20/200~. Thus many cases in this category may actually more or less severely impaired (American Medical Association, 19841. Additional Impairments A key factor in mobility problems is the presence or absence of other impairments. More than 50 percent of individuals with visual impairments also have one or more other impairments (Kirchner, 1985), either due to the same pathology (as in diabetes or in Usher's syndrome, in which deafness occurs) or with an independent etiology. The types and significance of such impairments range widely: mental retardation, affecting the ability to learn how to use an aid; emotional illness, which may affect the motivation to use an aid; orthopedic impairments, which limit ambulation directly; hearing impairments, which limit the use of some types of aids; and other health conditions, such as heart disease, which can result in weakness or pain. All these conditions

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19 affect the type of information that the aid must provide and the type of service it might provide--for example, assistance for a visually impaired individual who uses a wheelchair. The psychosocial characteristics of the individual that we have been discussing (e.g., income, access to services, impact of type of onset, etc.) provide relevant information for dealing with the disabling effects of vision loss on mobility that cannot be obtained from knowledge of the medical diagnosis alone. In fact, information on diagnosis is often used as an indirect (and weak) indicator of one or more of the above variables. Obviously, for purposes of the medical treatment of the pathology or for programs directed at prevention, the information on causes is more directly relevant. Knowledge of diagnosis might also be sought as an indicator of mortality rates. This informa- tion may raise difficult ethical issues with regard to public policy requiring the allocation of resources (e.g., for expensive mobility aids). In general, with the exception of diabetes, we do not have reason to expect high age-specific mortality rates due to the major causes of blindness in the United States. Social Factors Social factors affecting the need for, access to, and acceptability of mobility aids must also be considered. These factors are shared with the nonimpaired population. Some of them are relevant epidemio- logically, i.e., related to the rates of underlying impairment. Some have independent effects on the rates of disability--that is, two people with the same impairment may have different degrees of disability depending on their social status. The latter effects occur because social groups have differential access to resources, and/or social norms make certain tasks more important; cultural influences may also make certain types of mobility aids unacceptable. Several national studies, which differ in the ways they identify the population with visual loss (and therefore use different estimated prevalence rates) nevertheless lead to fairly consistent generalizations about which social factors are important and in what connections. Specifically, age has been consistently found to be the strongest correlate of rates of visual impairment--prevalence rates increasing with age. Age is also one of the main bases for defining social roles and therefore the scope and nature of mobility tasks. Age may also operate through social psychological means to indicate sources of resistance to the use of certain aids. A second major social factor is income. Income has been found to be inversely related to prevalence of severe visual impairment, either because vision loss has led to loss of employment or because poverty has led to poor health conditions or poor access to health care. Among persons with severe visual impairment, those with low income are more likely to incur greater disabilities and greater handicap. This correlation may result from having fewer of the resources needed to accomplish tasks and receiving generally less social approval to maintain their roles as fully functioning employees or citizens.

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20 Economic factors not only affect the individual, but also involve aggregate costs to society as a whole. A 1976 report on the social and economic costs of visual disability (Cahill and Woolsey, 1976) estimates that the loss in tax revenue and the costs of rehabilitation services, supplemental security income, eye care, etc., Is over 9350 million (in 1976 dollars) per year. In addition, there is an estimated loss of income of over $1.4 billion and direct medical costs, which probably cannot be reduced, of approximately $3.6 billion per year (in 1976 dollars). In 1984 there were over 250,000 tax exemptions on federal income tax returns claimed for blindness. APPROACHES TO AIDING MOBILITY There are two major elements of the mobility problem that result from blindness. First, the blind traveler with no pattern vision must avoid obstacles and detect drop-offs. The second problem, which is less obvious and equally serious, is navigation. Sighted travelers have many landmarks, most of which are known through vision, to guide their way. These landmarks not only identify the location but are used in the memorial representation or cognitive map of the area. Deprived of vision, the blind person must use other types of landmarks and information to orient and navigate. A variety of aids have been developed to help the blind traveler. These include long canes, dog guides, and electronic travel aids. A variety of ETA s has been developed, including sound echo ranging devices, reflected light ranging devices, a computer vision system that speaks messages to the blind traveler, and a dog guide robot. ETAs can be roughly classified using a two-way classification scheme, illustrated in Figure 3. One dimension of the classification scheme derives from two philosophical approaches to the problem: sensory substitution and sensory supplementation. Sensory substitution attempts to use one of the blind person's remaining sensory systems as a substitute for vision. In this approach, the function of an ETA is to transduce and transform visual information into information that can be perceived by another sense. Both the factual and auditory sensory modalities have been used as substitutes for vision. Critics of this approach point out that converting visual information to auditory information could overload the capacity of the auditory system and that the ETA's auditory signal often competes with naturally occurring and useful auditory information. Sensory supplementation starts with the observation that many blind people achieve a high degree of mobility without electronic aids. The function of an ETA therefore is to provide additional information that is critical and not available otherwise. A device that could detect an object blocking a path and signal its presence supplements the informa- tion already available to the blind traveler. The problem dealt with by this approach is to discover what information about the environment is necessary for mobility and, of equal importance, when it is needed. Critics of this approach point out that the critical information is often embedded in a complex array of sensory information. Moreover,

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21 Transduce and Translate Transduce, Process, and Translate Sensory Substitution Supplementation Sonicguide Seeing with skin Mowat Sensor Guide Dog Robot Laser Cane Computer Vision Pathsounder Nottingham Obstacle Detector FIGURE 3 Two-way classification scheme of electronic travel aids. the critical information may be relational and dynamic in its nature. Human sensory systems have the ability to analyze and interpret complex information flows, and this ability is lost with substitution systems. The second dimension of the classification scheme divides ETAs into two categories: those that transduce and transform environmental information and those that transduce, process, and then transform environmental information (see Figure 3~. The boundaries of the classification scheme are not sharp; some of the devices categorized actually straddle the boundaries or have aspects that fit into more than one category. This is especially true of the signal processing that goes on in the device, since few if any devices simply transduce environmental information. Of all the devices listed, only the Guide Dog Robot attempts to comoletelv solve the navioati on Oral "m _~ ~ ... it contains a complete internal navigation system. All the other devices assume that the cognitive capabilities of the blind person will suffice if the appropriate information is provided through sensory substitution or by information supplementation. PATTERNS OF USE AND NONUSE It is significant that none of these devices seems to be widely used or very popular. The initial impetus of ETAs came from engineers and researchers. The primary evaluation and testing concentrated on

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22 the mechanics of the device and the testing of the unique application of some instrumentation (e.g., lasers). These devices and the promise of new technologies were initially viewed as viable alternatives to the long cane or dog guide. After greater interaction with mobility specialists and other professionals working in the area of blindness, ETAs were suggested as a supplement to the primary mobility aid (i.e., the long cane or dog guide). It has only been during the last 15 years that follow-up evaluations have been done to determine the usefulness and success of ETAS. There have been very few studies of this nature published, and they represent a great deal of variation in methodology, sample size, and number of data gathered. Sample sizes range from 5 to 74 individuals. The methods used for gathering data include mail questionnaires, phone questionnaires, direct observation, and personal interview. The length of time the visually impaired person had the device ranged from a few months to about 11 years. The ETAs used by the subjects included the Soniaguide, the Mowat Sensor, the Laser Cane, and the Russell Path- sounder. (See Chapter 6 for a description of these aids.) Airasian (1973) mailed questionnaires to 94 individuals trained to use the Sonicguide (74 were returned). Many dimensions of attitudes about training f design difficulties and inconveniences, and adequacy of the device, range, and signals were gathered from the questionnaire. One basic question on the questionnarie was whether the person still had the Sonicguide. More than 10 percent no longer had the device, 11 percent still had it but had not decided about returning it, and 79 percent planned to keep the device. Darling et ale (1977) evaluated the 26 blind veterans receiving ETA training at the Western Blind Rehabilitation Center in Palo Alto, Calif. The procedure involved a phone survey and direct observation in the veterans' home area. Of the 26 veterans who had been trained, 3 had moved and 5 did not use the device. Of the remaining 18 subjects, 12 had the Sonicguide and 6 had the Laser Cane. The time since training ranged from 1 to 5 years. Of the 12 veterans having the Sonicquide, 5 were using it and 7 did not use it. Of the 6 people who had taken the laser cane training, only 3 were using the aid. Therefore, of the original 26 veterans, only 8 were known to be using an ETA. Farmer (1978) reported on 18 veterans who completed training in the use of the laser cane. Of these individuals, 11 people were using the laser cane for a period of 2 to 8 years. A telephone interview was conducted by Morrissette et al. (19811. This study involved 15 veterans who had been trained to use the Mowat Sensor. The length of use varied from 3 to 24 months. All subjects reported the aid to be helpful and continued to use it, although the amount of use varied as well as the particular uses. Finally, Simon {1984) studied five individuals who received their training at the New York Association for the Blind. Four received training with the Laser Cane and one was trained to use the Sonicguide. The training took place 3.5 to 5.5 years previous to the telephone interview. All five individuals reported that they still used the devices.

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23 These studies represent four separate and independent efforts to determine the success and utility of ETAs. On the basis of personal communication with ETA distributors, it was determined that approxi- mately 3,000-3,500 devices had been sold by 1985. These data, which are anecdotal and crude at best, are not a true representation of the number of devices owned by visually impaired individuals: many of the devices were sold to agencies for training, research, and/or demonstrations, and not to individual users. RECOMMENDATIONS On the basis of these findings, the working group makes the following recommendations in the area of information regarding the demography of blind and visually impaired pedestrians. Surveys of ETA Users and Technology Diffusion Approximately 3,000-3,500 electronic travel aids have been sold; this represents a small fraction of potential users. Very little is known about who purchased these ETAs, whether they remain in service, and whether training was adequate. Studies designed to evaluate ETA performance have sampled fewer than 5 percent of the 3,500 purchasers of these devices. It would be helpful for researchers to work toward developing a model of the diffusion of mobility-related technologies, drawing on the general literature on the diffusion of innovations. Current experience suggests that key groups in such a model would include, in addition to the population of potential users of mobility technologies: (1) rehabilitation personnel and mobility specialists, (2) administrators of agencies that provide mobility training, and (3) opinion leaders among blind and low-vision consumers. RECOMMENDATION: We recommend that a systematic survey of the total or a large sample of ETA purchasers be carried out. This survey should obtain demographic data on purchasers, training history, data on when, how, and how often the devices are used, individual differences in ETA use, and some measure of users' satisfaction with the devices. For a survey of this type to yield broadly useful data, comparison groups should be sampled from among the users of dog guides and long canes; it is very likely that these groups overlap. The study should be designed to estimate the probabilities of multiple device use (e.g., Sonicguide and dog guide) and to reveal the device selection factors that are currently operating in the marketplace. RECOMMENDATION: We recommend that a study be designed on the dif- fusion of mobility-related technologies. It could be done through a survey of rehabilitation personnel, mobility specialists, administra- tors, and opinion leaders among blind and visually impaired consumers. The study should gather data on geographic distribution of potential

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24 users, relevant training and experience, attitudes toward alternative technologies, and interrelations with the other groups. Consideration should be given to the cost-effectiveness of ETAs. A Normative Data Base RECOMMENDATION- There is an urgent need for a normative data base that contains information about the entire population of visually impaired and blind people. It should be possible, among other things, to interrogate this data base for information about personal data that indicate readiness for various sensory aids and how sensory readiness changes as a function of maturation and development, from infancy to old age. A Survey of the Needs of Older Blind People The prevalence of blindness in the population is greatest among older people. More than half the blind people in the United States today are over the age of 64. Given the growing proportion of people in the older age groups and the particular mobility needs of the elderly, we need to known more about the mobility requirements and preferences of elderly blind and visually impaired people. RECOMMENDATION: We recommend that a survey be conducted of the mobility requirements and preferences of elderly blind and visually impaired people. The survey should be designed to yield information about the variety, severity, and distribution of their visual impair- ments and of other sensory, motor, and cognitive impairments that may affect their need for and ability to use mobility aids. The survey should also provide a description of their travel requirements and an indication of the travel techniques and aids that would be most helpful in meeting those requirements. Review and Analysis of Existing Data Bases There are no nationally representative data bases designed to provide measures describing the number or characteristics of visually impaired people who have specific mobility needs and problems. The opportunity does exist to obtain information from existing data bases that in the short run and at little expense could provide generally useful information. RECOMMENDATION: We recommend that existing national (or more local) representative data bases be reviewed and analyzed to extract information on the specific mobility needs and problems of visually impaired people. Likely sources include the ongoing Health Interview Surveys of the National Center for Health Statistics as well as the Work and Disability Study of the Social Security Administration

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25 conducted in 1978. Studies conducted for purposes of public transportation planning might also be likely candidates for the extraction of such information. Study of Multiple Impairments On the basis of national studies, we found that more than 50 percent of the severely visually impaired population has at least one additional impairment. RECOMMENDATION: We recommend that an intensive study be conducted on the interaction of visual impairments with other cognitive, sensory, and physical impairments and their effect on mobility problems. Development of a Research Agenda Efforts by engineers and inventors to develop electronic aids for the blind have been sporadic and piecemeal. All too often, when a new aid is developed, it has all the inherent difficulties of previous attempts. The development of specific guidelines and research protocols, which can systematically evaluate aids and make recommendations for future scientists, is needed since funding is so limited. Progress can be made more efficiently and quickly through the accumulation of research findings rather than by individual trial and error. RECOMMENDATION: We recommend that either a federal agency or professional association concerned with these Problems convene an : ~ ~ _ _ . ~ . . _ . ~~cera~sc~p.~nary pane' to define a basic research agenda (or minimum data set) that would be widely disseminated to enable researchers working with small samples to produce reports that could permit cumulation of findings across studies. Models for this activity may be sought in the area of research on long-term care and possibly in clinical research areas identified by the National Institutes of Health.