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Health: Living With Low Vision

Posted by Good Times on

While there have been amazing advances in the prevention and treatment of eye diseases, tens of thousands of Canadians every year are told that they have vision loss that can’t be corrected with glasses and is severe enough to interfere with daily tasks such as reading a prescription label or glucose meter, using an ATM, and navigating safely down the street.

This condition, known as low vision, is much more common than total blindness; 90 per cent of the clientele of CNIB (the charitable organization formerly known as Canadian National Institute for the Blind) are affected by it—45,000 of the 50,000 who seek CNIB’s help each year and as many as 450,000 of the half-million Canadians the agency estimates are living with significant vision loss. Moreover, since vision loss is increasingly common with age—affecting one in four people 75 or older—those numbers are poised to surge over the next 25 years due to a projected doubling in the population of those over age 60.

Low vision not only makes daily chores more challenging and cuts into quality of life, but also threatens health and safety, explains Tanya Packer, a professor and the director of Dalhousie University’s School of Occupational Therapy, in Halifax. Compared with similar-aged adults with normal sight, she says, “Canadians with vision loss are at greater risk for social isolation and reduced community participation,” factors that are linked with increased odds for poor health and a reduced life expectancy. “They are also twice as likely as others to fall, four to eight times more likely to fracture a hip, and three times more likely to experience clinical depression, and they have a higher likelihood of nursing-home placement and even premature death.”

While there aren’t any treatments that can restore sight to those with low vision, there are tools that can help them make the best use of their remaining vision and continue to live as independently as possible. “A lot can be done in terms of low-vision rehabilitation,” stresses Susan Leat, a professor at the University of Waterloo’s School of Optometry and Vision Science.

To understand why the technology, techniques, and training to improve the lives of people with low vision were developed and how they have helped, it’s worthwhile to understand a bit more about some of the most common causes of vision loss and how they affect eyesight.

 

Get Checked Before It’s Too Late

“The three biggies in Canada are macular degeneration, diabetic retinopathy, and glaucoma,” Leat says.

In age-related macular degeneration (AMD), a deterioration of the centralmost part of the retina, “the central vision gets blurry and eventually you can lose it altogether,” she says. Photo-simulations of what a person with AMD sees show a clear picture marred by black blobs in the middle. “There are two things wrong with that: one, it makes it look as though your side vision is clear, but of course that’s not the case, because our vision is only really clear at the very centre of what we call fixation, which is where we’re looking.”

“Our peripheral vision is very different from our central vision,” says Aaron Johnson, an associate professor of psychology at Concordia University in Montreal. “There’s an easy way to demonstrate that: if you stare ahead and put your fingers up, you can see all five fingers quite clearly, but if you keep staring and move your hand over to the right or left, things soon start to blur—you can still kind of see your hand, but you lose the detail.”

The other misleading quality of those simulation photos, Leat says, is that they give the impression that you can simply peer around the “black blob” obstacle. “When you have macular degeneration, this central vision loss moves wherever you move your eyes.”

Diabetic retinopathy, on the other hand, “causes more of a patchy sort of vision loss,” Leat says. “So again, you can lose central vision, but you can also lose patches around it. It’s also more variable from day to day because it’s associated with bleeding and leakage that happens at the back of the eye.”

In the case of glaucoma, Leat says, “often a ring around your central vision is what’s lost, and if the condition progresses, it can move inwards and eventually affect your central vision, as well.” In contrast to central-vision loss, which interferes with recognizing faces and with tasks that require seeing fine detail—such as reading, applying makeup, and doing needlework—peripheral-vision loss can affect your mobility: imagine trying to navigate around obstacles like lampposts and curbs while peering through a tube.

It’s worth noting that it’s possible to lose quite a bit of vision before you notice there’s a problem—and this is only partly due to any changes occurring gradually.

“We all have a blind spot in each eye,” Johnson explains, “but we’re not aware of this in our day-to-day life because our brain takes information from one eye and transfers it to the other,” filling in the blank. (These blind spots exist because when images projected onto the retina fall where the optic nerve exits the eye, they cannot be detected—there are no photoreceptors at this point.) Scientists believe the same phenomenon occurs in eye diseases such as macular degeneration, and it’s not until the affected area reaches a certain size and the vision loss has progressed substantially that the brain can no longer compensate and the person notices a problem.

Because the brain pays less attention to peripheral vision, this type of loss can be quite advanced before it becomes perceptible. “A lot of folks who have glaucoma often don’t get to rehab until they’ve fallen and broken something and somebody decides to check their vision while they’re in hospital,” says Olga Overbury, a professor at the University of Montreal’s School of Optometry who specializes in low vision.

Ary Tsotras, 45, of London, ON, can attest to this fact.

“One day, I was driving my car and ran straight into the side of a bright-yellow school bus because I didn’t see the red light,” he recalls. It turned out that Tsotras’s peripheral vision had been significantly eroded by a progressive eye disease called retinitis pigmentosa (RP), which causes a pattern of vision loss similar to that from glaucoma. While RP isn’t currently treatable, glaucoma can often be arrested with medications or surgery if caught early—a compelling argument for having comprehensive eye exams at the intervals recommended by your physician or eye specialist.

What Can Be Done

If you are diagnosed with low vision, ideally you should be referred to a care provider who specializes in this area. CNIB locations across the country offer low-vision assessments, as do some optometrists and ophthalmologists, as well as a handful of low-vision clinics within hospitals and universities.

Unfortunately, referrals don’t always happen. When researchers affiliated with the MAB-Mackay Rehabilitation Centre in Montreal launched a study to try to identify the factors that prevent people from accessing low-vision rehabilitation, “50 per cent of the people we interviewed said they had no idea there was any such thing, and they’d been going to ophthalmologists pretty well all their lives,” Overbury says.

This is even more surprising because awareness may be highest in Quebec, as it’s the only province where the majority of low-vision services are publicly funded, says Susan Fraser, one of the study co-authors, who is now an assistant professor at the University of Ottawa’s Interdisciplinary School of Health Sciences. “That’s not the case in the rest of Canada,” she says. (Quebec’s provincial health plan also covers the cost of most devices that might be prescribed for someone with low vision. It’s one of only four Canadian provinces that provide at least partial funding for such assistive devices, the other three being Ontario, Saskatchewan, and Alberta. Veterans Affairs Canada is another source of coverage, for those who qualify.)

The first step in low-vision rehabilitation is something called a functional visual assessment.

“There are four components to your vision,” explains Alex Mao, an optometrist who heads the low-vision clinic at the Ivey Eye Institute at St. Joseph’s Health Care London (ON) and an assistant professor at Western University’s Schulich School of Medicine & Dentistry.

The first of these components, visual acuity—the ability to clearly discern letters of a certain size at a set distance—is what’s typically measured during a routine optometry exam. In addition to visual acuity, a functional visual assessment tests the other three spheres: contrast sensitivity (the ability to pick out ever more indistinct objects from a background of a similar shade), visual field (the total area in which objects can be seen when you focus your eyes on a central point), and colour vision. After this exhaustive exam, which takes about an hour and a half, Mao says, “we can come up with a rehabilitation plan to maximize the patient’s existing vision,” by enhancing, where possible, different components of functional vision.

For example, some people with poor contrast sensitivity and compromised colour vision might benefit from specially-tinted lenses. These can also cut glare, to which many people with low vision are especially sensitive. For someone who’s lost half his or her visual field due to a stroke, “there are glasses with prisms, which basically bring images from the side into the central vision,” explains Dr. Samuel Markowitz, a professor of ophthalmology and visual sciences and director of the low-vision rehabilitation program at the University of Toronto, and an ophthalmologist at Toronto Western Hospital. “The idea is to train the patient to use these glasses to be aware of some things on the affected side, kind of like an early warning system.”

Low-vision specialists can also offer advice on strategies to make certain tasks easier with this type of visual impairment: for instance, tilting a book so that instead of reading from left to right, you’re reading from the top of the page down. “It sounds strange, but it actually works quite well in some cases,” says the University of Waterloo’s Susan Leat.

While special lenses may enhance vision by what might seem a negligible amount to someone with normal sight, the effect can be dramatic for someone with low vision, Ary Tsotras says. “A 10 per cent improvement might be the difference between me falling off the sidewalk and not,” he adds. For someone else, it might mean being able to make out the numbers on a bus and therefore being able to take public transit rather than relying on taxis and family members for transportation, Markowitz says.

 

Devices and Strategies

A strategy that can help people with central vision loss make the best of their remaining vision is identifying and learning to use a “sweet spot” on the retina—by looking just above or below an object, for instance. “A new locus on the retina develops that has better vision than the rest of the peripheral vision—this is a natural occurrence,” Markowitz explains. “There are also devices and training methods that help people see better with that preferred retinal locus—or PRL.”

These techniques initially used sophisticated expensive equipment few ophthalmologists would have in their offices, but University of Toronto and Toronto Western Research Institute researchers have been working to make the training more affordable and convenient by trying to adapt it for at-home practice via home computer or tablet.

Many people with central vision loss also benefit from a range of devices that magnify images.

“We’ve known for a while that one way of improving the ability to see detail in the periphery is to make things bigger,” explains Concordia University’s Aaron Johnson. “Traditionally this was done using either magnifiers or optical devices” for tasks like reading. “Then, in the 1980s, it started to be done with closed-circuit television,” he says. CCTV units, which come in projector-sized desktop versions (these run around $3,000) and portable tablet-sized varieties (about $1,500) suitable for reading menus and grocery labels, offer advantages over older devices. “At the flick of a switch, you can adjust contrast, or even reverse from black print on a white background to white print on a black background, which a lot of people find more comfortable to read,” says the University of Montreal’s Olga Overbury.

Today, iPads and other computer tablets, and even smartphones, can be used in much the same way, at a much lower cost; these options represent a relative bargain for devices that can also access the Internet, connect to video chat, and download e-books. (You can find videos detailing how to use the accessibility features built into the iPad and iPhone on the CNIB website, cnib.ca.)

A group of researchers at Montreal’s MAB-Mackay Rehabilitation Centre, led by Walter Wittich, is probing whether iPads work as well as CCTVs as a reading aid for people with low vision. So far, says Aaron Johnson, a member of the research team, “we’ve found there’s no difference in reading rates” between the two. The investigators hope to recruit more participants (to date, they’ve tested about 100) to find out whether iPads are useful for everyone who requires magnification (or if, for example, people with a more severe impairment might do better with CCTV) and test how effective they are for other routine tasks, such as reading a prescription label on a medicine bottle, looking up a number in a telephone book, and scanning a restaurant menu.

Devices like the iPad and iPhone can be an enormous boon for people who no longer have enough vision to read. “My iPad reads to me; it’s changed my life completely,” Ary Tsotras says. Had this type of technology existed when he lost his ability to see well enough to read, he says, he probably wouldn’t have been forced to shutter one business and completely reinvent his livelihood.

To magnify more distant objects, such as street signs, a small telescope is sometimes helpful. (It’s also possible to snap a photo of, say, the arrivals board at the airport with your smartphone and then enlarge the image.) Some types can even be mounted on glasses for activities that involve more extended use or images that are closer-up, such as when watching television.

Magnification, however, isn’t helpful for people who have a restricted field of vision. “If anything, it’s bad,” Overbury says. “If you saw through a pinhole and somebody made everything 10 times bigger, you’d see less of it.” So, in some cases, Western University’s Alex Mao explains, “we can use a reverse telescope to expand the field of vision: minification rather than magnification.”

However, for many people with vision loss, existing aids aren’t helpful for two key tasks. “We found in our study that the major complaints of somebody with glaucoma who has moderate to severe vision loss are mobility and contrast sensitivity,” says Yogesh Patodia, a medical student working with Mao to develop a device they hope will partially fill this gap.

A relatively low-tech tool useful for people with different types of vision loss is lighting: low-vision specialists can recommend the amount and type best suited to an individual patient’s condition and to specific tasks.

“People with low vision tend to have a much smaller range of what is optimal lighting for them,” Leat explains. “It depends on the condition. Very often, they prefer much higher levels, but sometimes lower levels might be best. People with low vision also have much more sensitivity to glare, so controlling the direction of lighting is important, too. We might also specify the type of lighting; for example, some people are much better with either fluorescent lighting or halogen lighting; plus, a lot of devices now use the new LEDs.”

 

More and More Help

A host of aids are available to facilitate doing different tasks with limited vision.

“There are all kinds of simple little gadgets in our store that can help,” says Sue Marsh-Woods, manager of service and operations for the Toronto-region CNIB. These include clocks with extra-large numbers, devices that emit sounds when the container you’re pouring liquid into is nearly full, and plastic templates for writing your signature.

Modifications to a person’s living quarters can make life easier, too. For example, if someone has poor contrast vision, marking doorways and stair edges with high-contrast stripes of paint or strips of tape may reduce the chances of bumps and falls.

For people who are still struggling at home after an initial assessment and consultation, CNIB offers one-on-one visits from a practitioner who can go into the home and provide individualized strategies and tools for improving independent living skills. “It’s very goal-based,” explains Marsh-Woods. “It could be something as simple as marking various readings on the oven dial so the person can set the oven to the correct temperature.”

For those who lack confidence in their ability to get around safely indoors or out, CNIB offers orientation and mobility training, which includes techniques for crossing roads and traversing sidewalks safely, as well as tips on how to make the most efficient use of a sighted guide when necessary. (If you know someone with low vision, you can find tips on this “sighted guide” technique at cnib.ca.) “Again, we would start with an assessment: What do they want to do?” Marsh-Woods says. “We assess their vision: Can they see street signs? Can they see curbs? We might then recommend a white cane if they need it and training on how to use public transit when vision is an issue.”

Tanya Packer, director of Dalhousie University’s School of Occupational Therapy, notes that CNIB’s Nova Scotia branch delivers a two-day occupational therapy workshop that also teaches practical community safety strategies such as how to break the hold of an attacker, since a visual impairment may render people unable to tell if someone is lurking over their shoulder at the ATM or to see who is approaching on the street.

“A self-defence expert provides guided learning, not because we expect people to be attacked,” she says, “but because knowing how to defend yourself gives a sense of control, confidence, and resilience that allows people to do things they never thought possible.”

Those qualities seem to come naturally to Ary Tsotras, who over the years has found new ways of doing the things he wants to do. “I’ve learned to adapt,” he says.

For instance, as a competitive runner, he may need a guide to run an unfamiliar course—but he trains solo in his neighbourhood by using his other senses and knowing how many steps it takes him to get from one corner to the next. “The impor­tant thing for people with low vision to understand,” he says, “is that it’s not the end—it’s just different.”

“There is hope,” says Dr. Markowitz. “Lots of people are sitting in the dark and despair because they haven’t yet found someone who can listen to them and give the service they need. But lots of things can be done for people with low vision, so persist until you find somebody who can help.” n

 

Low Vision: Low Priority?

The way low-vision services are funded in Canada is short-sighted, given the oncoming “silver tsunami” and the fact that rehabilitation can be incredibly helpful for people with low vision—allowing them to continue to live independently and preventing costly hospitalizations due, for example, to falls.

“The extent to which low-vision care is funded varies enormously between provinces—in most, it’s not funded very well,” says Susan Leat, a professor at the University of Waterloo’s School of Optometry and Vision Science. For starters, low-vision rehabilitation isn’t covered by provincial health plans outside of Quebec. “When someone has a stroke, the rehabilitation is regarded as medically necessary, so it’s paid for—for a certain length of time, anyway—whereas for vision care, for some reason, it’s not.”

(Coverage of low-vision devices is not much better: only four provinces—Quebec, Ontario, Saskatchewan, and Alberta—provide at least partial funding. For example, Ontario’s Assistive Devices Program will pick up 75 per cent of the tab for certain low-vision aids prescribed by a registered authorizer. It’s no wonder that a small 2006 survey of seniors with low vision found that half of them didn’t have a device they would otherwise have liked to have, with 50 per cent of this subgroup citing price as a factor.)

Furthermore, there are gaps in the funding that does exist: in Ontario, for example, a set fee for low-vision services is covered only when those services are provided by an ophthalmologist, although few provide this type of care (it’s more commonly offered by optometrists). “That’s obviously very limiting for people,” Leat says.

“This is a health-care problem,” says Dr. Samuel Markowitz, a professor of ophthalmology and director of the low-vision rehabilitation program at the University of Toronto, “and governments have to pay attention to that. You can’t base those kinds of services on donation and charity.”

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