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AFB JOURNAL OVISUAL
IMPAIRMENT& BLINDNESS
  
Expanding possibilities for people with vision loss  
 

October 2008 • Volume 102 Number 10

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Guest Editor's Page

Print edition page number(s) 578-580

The opinions expressed in this editorial are those of the authors and do not reflect the policies or opinions of the Department of Veterans Affairs.


It ain't what we don't know that gets us into trouble. It's what we know for sure that just ain't so.

--Mark Twain

The year 2008 represents a new world for visual impairment in the United States and Canada. The demographics of vision loss have changed radically in the last several decades. Today, the greatest number of people with visual impairments are not children or young adults; rather they are seniors with age-related macular degeneration (AMD), who outnumber younger visually impaired adults and children by wide margins. According to the National Eye Institute, people 80 years of age and older currently make up 8 percent of the population, but account for 69 percent of those with visual impairment and blindness, largely from AMD. Indeed, macular degeneration is the cause of the majority of all visual impairment and blindness in Americans.

This matters because much of what we know for sure about visual impairment and vision rehabilitation "just ain't so" with macular degeneration. Why? Two key reasons.

Different life experience

Seniors are a population distinct from all others, including younger and middle-aged adults. Just as children have their own medical specialty--pediatrics--so seniors have theirs--geriatrics. Just as kids are not little adults, seniors are not wrinkled adults. They are unique physiologically, medically, and psychosocially. They require different rehabilitation strategies and approaches, different visual and functional devices, and different teaching approaches and methods for effective rehabilitation.

Age-related physiological changes in hearing, balance, agility, recovery time, learning patterns and memory make part of the difference. Seniors often rely on their vision to compensate for these other age-related losses, so that when vision is lost too, they are particularly vulnerable to age-specific functional declines and dangerous falls. This situation does not preclude them from being successful in vision rehabilitation, but it does mean that rehabilitation professionals must understand how to address these conditions and assume the responsibility for doing so, or else partner closely with other health care professionals who can address them.

When working with seniors, successful vision rehabilitation professionals may need to modulate the pitch and pacing of their voices, adapt their teaching practices to maximize learning, and take the physiological differences of seniors into account. Clients with low vision may need support canes, rather than long canes, to maintain safe balance when walking. They may need contrasting shower bars, contrasting color mats, and adaptive lighting in order to remain safe in the bathroom. With seniors, these considerations are not side issues but are an integral part of vision rehabilitation practice.

Seniors also present with a range of medical conditions that shape vision rehabilitation practice, possibly including a history of minor strokes, diabetes, early-onset Parkinson's, arthritis, hypertension, heart disease, osteoporosis, chronic joint or back problems, reduced range of motion, under- or overdosing on medications, and clinical depression as a result of vision loss. Vision rehabilitation professionals must recognize the symptoms of these conditions, understand their interplay with vision loss in compromising function, and address them as an intrinsic part of vision rehabilitation.

Seniors are also at a different life stage, with different skills and resources from younger and middle-aged adults, often with other profound losses in their lives--the loss of a spouses, siblings, jobs, or even homes as they move to retirement or assisted living facilities distant from their familiar neighborhoods. Successful vision rehabilitation requires understanding and incorporating these physical, psychological, and cultural differences that sculpt seniors' experiences of vision loss and influence their approach to rehabilitation.

Different visual experience

Because AMD creates patterns of residual vision distinct from all other conditions, it is easy to misunderstand or misinterpret the nature of the vision of seniors with this condition. AMD develops with a variety of patterns of central scotoma, the nonseeing area. A strongly preferred retinal locus (PRL) develops following damage to the fovea for most people with macular loss, and the PRL becomes the new area for fixation. The person whose PRL is to the left of the central scotoma needs different strategies from the person whose PRL is above or to the right of the scotoma. A ring scotoma--a circular, doughnut-shaped area of vision loss on the retina--significantly limits function but is not detectable with conventional acuity measurements. People with ring scotomas may have 20/20 acuity and be able to recognize small individual letters but not read whole words, and magnifiers may make it even more difficult to use the small central area of vision.

Another aspect of AMD is loss of contrast sensitivity. Even early macular degeneration reduces contrast sensitivity, which compromises function while leaving high-contrast acuity, as measured by a black-and-white letters on a chart, intact. People with good acuity but loss of contrast sensitivity find it difficult to recognize faces, see food on plates of similar hues, spot curbs and steps, or drive under certain light conditions.

In addition, unlike most other causes of vision loss, the central vision loss of macular degeneration is not apparent to others. Seniors with considerable functional vision loss appear nearly fully sighted to others. They make eye contact because of a lifetime of practice as sighted individuals, and they may move fluidly around a room because of intact peripheral vision, but these competencies can mask very real deficits that have profound impact on seniors' lives, health, and overall well being.

For all of these reasons, one of the "things we know for sure" that macular degeneration proves "just ain't so" is that legal blindness--20/200 acuity or a 10 degree visual field--is a reliable benchmark of function. Legal blindness is a political designation, not a valid index of the degree of functional vision loss from AMD or of the psychological impact of vision loss, both of which occur long before a senior reaches the benchmark of legal blindness. Two major funding sources for vision rehabilitation, Medicare and the Department of Veterans Affairs, have recognized and acted to assure that an artifical designation like "legal blindness" does not deter the provision of services to those who have functional deficits.

JVIB and AMD

The great strength of a peer-reviewed journal is that a variety of authors writing from different vantage points submit articles that are critiqued by a variety of reviewers from yet other vantage points. Intrinsic to this process is that the articles finally accepted for publication address discrete parts of an overall topic. The implication of such a process on this dedicated issue is that, by definition, only parts of the topic can be addressed. The fine articles in this issue present important parts of the story of macular degeneration's impact on individuals and on rehabilitation. Other articles that were submitted for this issue will appear in subsequent issues.

It is our hope that this issue and the focus it brings to AMD will encourage further thought and research in the field of geriatric vision rehabilitation and low vision practice and encourage a larger practice-wide discussion among JVIB readers of optimal approaches to this growing population. We look forward to reading more of this story as JVIB and the profession move forward.

Lylas Mogk

Gale Watson


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