This article provides an overview of combined vision and hearing loss or dual sensory loss. It includes strategies for auditory rehabilitation with this population and suggestions for how to make an audiology practice accessible for older adults with dual sensory loss.
Demographics of Dual Sensory Loss in the United States
The demographics of the United States population are changing with the segment of adults 65 years of age and older growing rapidly. By 2040, it is estimated that older Americans will constitute 20% of the United States population (Pleis & Coles, 1999). As people age, there are normal age-related changes in the auditory and visual mechanisms. Dual sensory loss, or hearing and vision loss combined, is increasing and will continue to do so as the number of seniors grows over the next several decades. In dual sensory loss, the degree of vision and hearing loss is reported to be significant enough to result in communication problems that go beyond difficulties experienced for either sensory loss alone (Saunders & Echt, 2007). Estimates of the percentage of people with dual sensory loss in those age 70 years and older range between 9% and 21% (Atorowitz, Brennan & Su, 2001). The incidence of dual sensory loss varies depending upon the definitions used to define hearing loss and vision loss, as well as on the method of data collection.
Age-Related Sensory Changes
Hearing loss is the third most chronic health condition affecting older adults. Approximately 30% of those over the age of 65 have some degree of hearing impairment, with estimates ranging from 70% to 90% of those over the age of 85 (Weinstein, 2000).
Presbycusis, normal age-related changes in auditory function, is caused by anatomical and physiological changes to the entire auditory pathway (Schuknecht, 1974). However, the aging of the auditory system is not uniform throughout the mechanism. Age-related changes in the peripheral and central auditory pathways impact speech understanding ability independently, especially in degraded listening conditions (Gates, Feeney & Mills, 2008).
Age-related changes in the visual mechanism are known as presbyopia. Normal age-related changes in vision include decrease in pupil size, loss of color sensitivity, glare sensitivity, delayed ability to adapt to the dark, reduced peripheral visual fields, and loss of depth perception (Kricos, 2007). Approximately 1% of Americans are legally blind. The definition of legal blindness is visual acuity with the best correction in the better eye equal to or worse than 20/200, visual fields less than 20 degrees, or both. Three million Americans are reported to have low vision, a term implying that an individual has significant vision loss but can accomplish tasks with the use of assistive technology and environmental modifications (Berry, Mascia, & Steinman, 2004).
Low Vision in Older Adults
The four most common causes of vision loss are age-related macular degeneration, diabetic retinopathy, cataract, and glaucoma (Congdon, O'Colmain, & Klaver, 2004).
Age-related macular degeneration may take one of two forms;dry macular degeneration and wet macular degeneration. Dry macular degeneration is more common, and is associated with deposits of drusen on the macula. Wet macular degeneration is characterized by the formation of abnormal blood vessels that leak fluid and cause scar tissue to form on the macula. Age-related macular degeneration results in a loss of vision to the central visual fields. This disorder will have significant implications for speechreading and sign language, as fine details may not be visible. Age-related macular degeneration also may cause problems reading fine print, seeing faces, viewing objects at a distance, and possible some delay in adapting to the dark (Horowitz &
Diabetic retinopathy will continue to be a growing problem due to the 23 million Americans diagnosed with Type 2 diabetes, and many more individuals who will be diagnosed in the future. In uncontrolled diabetes there are problems with the capillaries of the blood vessels in the eyes. This results in problems related to decreases in visual acuity, blurred or hazy vision, glare sensitivity, decreases in contrast sensitivity, and decreases in color discrimination (McDermott et al., 2009).
Cataracts result in blurred visual acuity, and can impact all facets of vision depending on the stage of the ocular disease. Typically cataracts are binocular. Cataracts are removed with a surgical procedure which ought to restore vision to normal or near normal. If left untreated, a cataract can cause permanent blindness (Horowitz & Reinhardt,1993).
Glaucoma is the result of an increase in the intraocular pressure in the eye which can result in degeneration of the optic nerve. Untreated glaucoma can result in permanent blindness. This eye disease will impact visual acuity and visual fields depending on the stage of the disease (Horowitz & Reinholdt, 1993).
These ocular conditions may coincide, or exist in isolation. For example, a diabetic may have diabetic retinopathy, and glaucoma or cataracts. The subpopulation of older adults who have a pathological condition as well as normal age-related visual changes may report significant impact on communication abilities, especially if they are not able to use visual cues to compensate for degraded auditory information.
Dual Sensory Loss
Individuals with dual sensory loss report poorer self-health, depression, reduced quality of life, and less interaction with social networks (Brennan & Bally, 2007). Older adults with dual sensory loss are more likely than their non-impaired peers to need help with instrumental activities of daily living, such as personal care, medication management, or phone use. They are also more likely to need help with mobility, shopping, and are more likely to live with family members (Brennan, Horowitz, & Su, 2005). People with dual sensory loss may cause greater risks for falls than those with single sensory loss. This is a perilous possibility, as falls are the third leading cause of death in the elderly (Jacobsen, 2002). While balance typically is considered a vestibular function, vision and somatosensory information also play a significant role. Professionals should observe patients for balance issues, as well as review this area on case history forms and during the intake dialogue. When a balance problem is present, the audiologist should work in conjunction with the vision specialist and, possibly, a physical therapist to design the most appropriate intervention plan. Orientation and mobility training should address falls and fall-prevention to avoid injuries that can be devastating for seniors with coexisting conditions (Busacco, 2009).
When dealing with dual sensory loss it is imperative that information is maximized through each sensory system so that additional auditory and visual compensatory cues are available. It is critical that an older adult with dual sensory loss receive amplification for safety and quality of life purposes. Amplification should include bilateral hearing aids coupled, whenever possible, with a personal listening system. The controls on the hearing aid should be minimal with as many automatic features as possible (Kricos, 2007).
Weinstein (2000) stated that cochlear implants, preferably bilateral, should be considered for those older adults who meet the qualifying criteria. Following cochlear implantation, a comprehensive auditory rehabilitation program that includes auditory-visual speech perception training, listening training, communication skills enhancement, and psychosocial counseling should be implemented.
The recommendation of a variety of visual and auditory devices can make a senior more confident, and may allow them to live independently. Wireless pagers used in the home can help with identification of environmental sounds such as smoke alarms, alarm clocks, telephones, and doorbells. A hearing dog can help a person identify sounds, increase independence, and live safely.
A comprehensive auditory rehabilitation program should be developed and implemented in consultation with family, significant others, and professionals using an interdisciplinary team approach. Professionals who may be members of the team include a geriatrician, occupational therapist, social worker, physical therapist, psychologist, and speech-language pathologist. The members of the interdisciplinary team will vary depending on the unique medical and rehabilitation needs of the older adult.
Given that a number of older patients with dual sensory loss will seek hearing and balance services, it is important that an audiology practice be physically accessible. Although this may require an initial monetary investment, such accommodations will likely result in patients reporting greater customer satisfaction with audiology services. The positive "word of mouth" marketing that will be the outcome of the physical accessibility of the practice will offset the initial investment, especially as older adults are the primary users of hearing aids.
Assistive technology that is helpful for patients with vision loss include hand-held magnifiers, lamps with magnification, portable readers, hand-held telescopes, and Closed Circuit Television (CCTV) (Watson, 2001). These assistive vision devices can also help patients see controls of amplification devices. In addition, auditory rehabilitation education materials can be magnified. It is also recommended that video materials available for patients be captioned to maximize auditory and visual information. By having several of these vision devices available in the audiology practice for demonstration and practice, the older adult with vision loss will be more confident in learning about hearing aid technology and will be more likely to use the devices independently and successfully.
Lighting is crucial in the audiology testing and counseling areas. Whenever possible, dimmers should be used as well as incandescent lighting. Lighting issues for those with vision loss may include sensitivity to glare and light, color discrimination, and reduced contrast sensitivity. Furniture should be placed strategically with ample space for navigation with a cane or a dog. Office support staff ought to orient the patient with dual sensory loss to the physical space. In addition, providing the patient with detailed verbal instructions throughout the session will be very beneficial and may reduce the patient's anxiety.
Forms such as case history, contracts, education materials, hearing handicap scales, and communication scales should be printed in fonts of size 14 or larger. Printed materials should have good contrast with black print on white background on non-glossy paper as the preferred choice to maximize contrast sensitivity. If the audiology practice is providing services to individuals who are legally blind then Braille materials should be available.
According to Kricos (2007), time will be better managed if information, such as the case history intake, is sent out in advance of the hearing or balance evaluation. It also may be helpful to ask the patient to provide reports from vision specialists so that the audiologist is informed about the extent of vision loss. At the time of the evaluation the audiologist can do a quick vision screening using the Snellen chart to obtain information on visual acuity status. The Pelli-Robinson chart can be used to assess low contrast vision required for reading printed materials and for seeing fine details required for speechreading.
Every audiology practice should have assistive listening devices available for use during case history intake and counseling sessions, especially when dealing with a patient who has a moderate or greater degree of hearing loss. The use of these devices will increase conversational fluency, demonstrate the technology available, and illustrate communication benefits. Frequent verbal and physical interaction with the patient during the test session is important. It may be wise to use an audiology assistant or ask a family member to remain in the test booth to make the patient more comfortable during the evaluation.
If the audiology practice has a professional website then steps can be taken to maximize its accessibility for those with vision loss. Features of an accessible website include the ability to change the font size, ample spacing between the letters and words, best color for contrast sensitivity, and good visibility of images. Every image should be accompanied by text descriptions should the patient access the website using speech synthesis software. It would be beneficial to ask a vision specialist to visit the website and audiology practice to provide feedback about their accessibility to patients with significant vision loss.
Each patient with dual sensory loss must have an individual audiologic rehabilitation plan that involves both hearing and vision professionals working in tandem so that the most appropriate assistive technology and rehabilitation will be recommended.
At this time there is limited research on dual sensory loss in the elderly population. Some possible topics for future research include: best practice models for auditory rehabilitation with this population;effective educational models for vision, hearing professionals, and consumers;and the role of preventative medicine in reducing the incidence of dual sensory loss. Such research information will allow audiologists to provide the most effective hearing healthcare services to improve the quality of life for dual sensory impaired individuals and their families.
This case study incorporates many of the principles addressed in this article related to providing a comprehensive auditory rehabilitation plan for an older adult with dual sensory loss.
Dr. B. is an 85 year old retired physician living in the community with his spouse of 55 years. He has a 10-year history of a moderately-severe sensorineural hearing loss, bilaterally. At present, he is not using hearing aids. Dr. B. is an insulin-dependent diabetic for the last 20 years. At this time his diabetes is uncontrolled. His ophthalmologist diagnosed advanced retinopathy about one year ago. Dr. B. is considered to be legally blind. His wife stated that for the past year he is clinically depressed and anxious. He takes psychiatric medications on a daily basis. During the past 6 months Dr. B. has been receiving services for low vision including mobility and orientation training. He also has acquired several vision assistive technology devices such as a portable reader, magnifiers, and computer-aided technology. Dr. B. has been working with a low vision specialist, occupational therapist, social worker, and psychologist as members of his interdisciplinary team.
The following auditory rehabilitation plan has been proposed for Dr. B.:
- Bilateral hearing aids that are digital and programmable with an automatic telecoil and automatic volume control (no manual volume controls).
- FM listening system for group situations and television viewing.
- Hearing technology orientation involving a low vision specialist and audiologist. Involvement of a family member or significant other is highly recommended. An extended appointment time, or multiple appointment times may be necessary.
- Evaluation of the home environment to ascertain if visual and auditory alerting systems are necessary.
- Recommendation for psychosocial counseling evaluation for patient and family members to assist with successful adaptation to dual sensory life, and to improve issues related to quality of life.
- Linkage with local, state, and national resources for both hearing and vision loss.
- Ongoing monitoring of hearing and vision status.
The following organizations offer excellent resources on vision loss:
American Foundation for the Blind
Helen Keller National Center for Deaf-Blind Youths and Adults
National Eye Institute
National Federation of the Blind
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