American Academy of Ophthalmology Web Site: www.aao.org
Clinical Update: Comprehensive
Faith, Hope and Adaptation: Low Vision Reconsidered
The message is clear and compelling: Low vision testing and rehabilitation hold huge potential, particularly with the aging of America. And low vision specialists want community ophthalmologists to raise their level of consciousness about trends in the field, the impact of vision loss on individual patients and the value of low vision ophthalmic testing and care.
“Low vision rehabilitation options are vastly underutilized, and that’s the biggest problem,” said Rebecca K. Morgan, MD, professor of ophthalmology at the University of Oklahoma in Oklahoma City and a member of the Academy’s task force on low vision rehabilitation. “Low vision rehabilitation should be a component of care for all patients who have irreversible vision loss,” she said. For community ophthalmologists, providing this care can be as simple as telling patients with early vision loss about special reading lights. It’s not difficult to make a big difference in a low vision patient’s quality of life, she said.
Trends in Low Vision
Physician and patient attitudes about low vision are changing as testing goes beyond the Snellen chart and rehabilitation assumes a more holistic approach. “It’s more about lives than eyes, more about the whole person not just the eyeball,” said Ronald J. Cole, MD, clinical associate professor of ophthalmology at the University of California at Davis and one of the first members of the Academy’s low vision rehabilitation task force.
In the past, ophthalmologists subscribed to the notion that there’s nothing to be done about patients with irreversible vision loss, Dr. Cole said, but now they can tell patients about strategies and services that can help. And, he said, patients need to understand they don’t have low vision problems just because of aging. There can possibly be restoration of some function and independence.
The burden on elders. As increasing millions of Americans age, the numbers of older people with low vision is exploding, according to August Colenbrander, MD, a pioneer in low vision advocacy and now affiliate senior scientist at the Smith-Kettlewell Eye Research Institute in San Francisco. Age-related macular degeneration is the No. 1 cause of low vision in older Americans, followed by diabetic retinopathy and glaucoma, Dr. Colenbrander said. Degenerative diseases, such as retinitis pigmentosa, represent a far smaller percentage.
“Vision loss that is not amenable to refractive or medical or surgical treatment tends to occur increasingly in older individuals,” Dr. Morgan said. The Academy estimates that AMD accounts for 45 percent of low vision patients and that every year about 200,000 Americans lose significant vision from neovascular complications of AMD. Young people represent only 4 or 5 percent of low vision patients, and they present with a different set of visual problems than older patients.
Dr. Cole said his practice bears out those numbers, with 90 percent of his low vision patients being older than 65, with macular degeneration the most common condition. AMD, in fact, is one of the major forces that started ophthalmologists looking at forms of rehabilitation beyond just relying on magnification, he noted. “Patients need to realize that with help it is possible to compensate for vision loss and restore some independence.”
Not All Tests Are Equal
Comprehensive low vision evaluation begins with a functional history, Dr. Morgan said. That history may take 20 to 30 minutes, which is a challenge in a busy community ophthalmology practice. The major components of visual function testing are visual acuity, visual field test and contrast sensitivity levels, although patients may also undergo glare, color and visual motor integration testing. Dr. Morgan said five functional areas need to be addressed in each patient: reading ability, ability to complete activities of daily living, community participation, safety issues and overall well-being.
Life beyond Snellen. Low vision testing probes deeper than standard testing. Visual acuity represents only one measure of functional vision, according to Dr. Cole. “The Snellen chart is not definitive for low vision patients because often they cannot even see the largest letter on the chart,” he said. “The biggest difference is in functional vision.”
Dr. Colenbrander agreed. “It is a mistake to think of the Snellen test as the only parameter of vision, but it has a role as an easy, fast and inexpensive test.” Contrast sensitivity is also important, he said. A physician may find that a patient’s high contrast acuity is fine, but the patient may continue to complain of a vision problem. The reason may be a decrease in low contrast acuity for which physicians do not test often.
Calling all contrasts. “I have developed what I call mixed contrast cards, which have high contrast, black lines on the left and low contrast, gray lines on the right, either as a letter chart or a reading chart,” Dr. Colenbrander said. “Normal is one or two lines difference. In macular degeneration patients, we may have up to four or five lines difference, and occasionally up to 10 lines difference, as much as the chart can measure. Interestingly, these differences seem to be independent of visual acuity.”
For elderly people, testing contrast sensitivity is especially important, according to Dr. Colenbrander. “In surveys, it is often found that difficulties with daily living skills relate more to contrast losses than they do to visual acuity losses.” He often advises patients to use contrasting colors at home to see better. “Do not serve white rice on a white plate on a white tablecloth.”
Don’t forget the foveola. Dr. Cole emphasizes the importance of assessing central vision in visual field testing. “It’s one of the things that is often neglected or overlooked,” he said. There is an inexpensive, simple, low tech approach to central field testing. “The central field assessment can be recorded on a test sheet held in an upright see-through stand between the patient and the examiner. A red laser pointer of appropriate sensitivity to detect seeing and nonseeing areas is used while observing the patient’s fixation pattern and viewing position, either binocular or monocular,” explained Dr. Cole.
New Hope From Rehab
A rehabilitation program is a team effort, Dr. Morgan pointed out. “There is medical management by the primary ophthalmologist, and it involves occupational therapists who provide training for individual patients,” she said. “It means further refinements in the selection of low vision aids and teaching patients adaptive strategies for using their residual vision as much as possible.” Traditionally, occupational therapists have not learned much about vision, but that is beginning to change.
Learning to use remaining vision. For example, if a patient has a scotoma, it is important to train her or him to avoid the nonseeing area and utilize the better-seeing area, the preferred retinal locus, according to Dr. Cole. He said he finds most patients are willing to change and are receptive and understand that it is necessary to change and adapt to different techniques. “Older patients have tremendous ability to make adaptations,” he said. “One of the most pleasant surprises is their brain plasticity. What they can accomplish is dramatic.”
Low vision gets some respect. Some universities and medical centers are beginning to teach ophthalmology residents about low vision testing and rehabilitation, Dr. Cole said, including University of California at Davis. And hospitals such as the Pomona Valley Hospital Medical Center in Southern California are beginning to offer low vision rehabilitation services.
Dr. Cole said he is planning to initiate a nonprofit foundation dedicated to providing low vision services for those who are uninsured or underinsured, expanding services and promoting low vision rehabilitation by education of the public and professionals in the field.
Many researchers are looking for great new technology that will simply do everything for low vision patients, said Dr. Morgan. Unfortunately, there is no such glitzy technological advance. Rather, it continues to be important to give patients options and coping skills, she said. “There’s no quick, easy fix in either testing or rehabilitation.”
Dr. Colenbrander agreed, “The change we need to see is one of awareness of what can be done through vision rehabilitation.”