Low vision is the term used to refer to a visual impairment that is not correctable through surgery, pharmaceuticals, glasses or contact lenses. It is often characterized by partial sight, such as blurred vision, blind spots or tunnel vision. Low vision can impact people of all ages, but is primarily associated with older adults.
Low vision care, also known as vision rehabilitation, is a service provided by an eye care or vision rehabilitation professional that helps maximize the remaining vision of someone who has a vision impairment. Low vision care typically involves an evaluation by the professional and the use of low vision devices (also called low vision aids), rehabilitation training and other techniques.
Low vision care can help make the most of the remaining vision that a visually impaired person has in order to gain back independence and increase quality of life. With the low vision devices and the training provided by eye care and vision rehabilitation professionals, many people with a vision impairment can continue to read, take care of their own finances, view photographs and watch television―all on their own!
The major eye diseases and conditions for which low vision devices are used are age-related macular degeneration, diabetic retinopathy, glaucoma, cataracts, retinitis pigmentosa, albinism, Stargardt’s disease and retinopathy of prematurity, among others.
The device needed depends on a number of variables and varies even among people with same eye disease, which is why a low vision patient should be evaluated by a low vision specialist who can demonstrate different devices to determine which one(s) work best for that individual’s needs.
Low vision devices vary for the same reason a carpenter carries so many different tools: each is good for a different task. Depending on the job, a carpenter may use a hammer, a wrench or a screwdriver. Likewise, a visually impaired patient may use a magnifier to read a pill bottle, a telescope to watch television, and a video magnifier to read a book. Each low vision device has its own set of tasks for which it is ideal and many people often use multiple devices.
Low vision devices make the image of an object appear larger and easier to see on the back of the eye in order to better focus on the image. The magnification that is provided by low vision devices allows the vision impaired individual to be able to see around the scotomas (dark spots) that are associated with low vision. The devices improve the contrast of the object so it can be more easily separated from its background.
Closed-circuit televisions (CCTVs) are now more commonly referred to as video magnifiers or electronic magnifiers and come in a variety of designs. The classic desktop magnifier can be compared to a microfiche machine often seen in a public library; an object (the film) rests under a camera and an enlarged image of it appears on a monitor above. Video magnifiers act similarly to other low vision devices in that they enlarge the image of an object so that it is easier to see.
A spectacle microscope is a pair of glasses that has a high-powered lens on one side and a clear lens on the other side. The glasses have to be used monocularly (one eye at a time) because of convergence issues. Spectacle microscopes are typically used for reading or other near tasks because in order to work properly, the object must be held very near to the eye.
Contrast-enhancing glasses, filters, tinted filters, absorptive filters, anti-glare glasses or glare control eyewear―block a certain range of light and are available in a variety of tints, the most popular being yellow, amber, orange, plum and gray. The glasses are usually designed to fit over prescription eyewear and improve the viewer’s visual contrast making it easier to see an object against its background.
Bioptic telescopes (also called bioptics) are small telescopes attached to a pair of glasses. They come in a variety of designs (attached to the top of a pair of glasses, drilled into the lens itself, etc.). When a user looks through the telescope at a distant object, the image is enlarged making it easier to see.
Low vision products are available only through eye care or vision rehabilitation professionals (usually called low vision professionals) who are trained in being able to determine which device is best for an end user and can then fit the device and provide training to ensure success with the product. All kind of low vision devices are available at our low vision clinic. Our low vision team will help you to select the devices according to your condition and needs.
The cost varies widely by the type of product and the brand
Causes of Low Vision
Some of the most common visual impairments that can cause low vision include the following
Age-Related Macular Degeneration (AMD/ARMD)
AMD is a leading cause of vision loss among Americans over age 60. It accounts for nearly half of all low vision cases. It is caused when the part of the eye responsible for sharp, straight-on vision – the macula – breaks down and causes a loss of central vision. There are two types of AMD, wet and dry. Wet AMD is caused by the growth of abnormal blood vessels under the macula. Central vision loss occurs rapidly with wet AMD. In dry AMD, light-sensitive cells in the macula slowly break down, leading to a gradual loss of central vision.
According to the National Eye Institute, more than 30 percent of Americans diagnosed with diabetes have some form of diabetic retinopathy. It is a major cause of blindness and is directly related to high blood sugar, which damages blood vessels. That damage affects the retina and can even lead to its detachment.
Glaucoma is the second leading cause of blindness. With glaucoma, portions of vision are lost over time, usually with no warning signs or symptoms prior to vision deterioration. For many, a decrease in peripheral vision is the first sign of glaucoma.
Over 20 million people in the US alone have cataracts according to Prevent Blindness America. It appears as a clouding of the lens of the eye. Retinitis Pigmentosa: This is a group of inherited diseases affecting the retina resulting in progressive vision loss. This type of vision impairment often begins in childhood with poor night vision and progresses over time.
There are also many additional causes of low vision, including strokes, TBI (traumatic brain injury) and other diseases common among a wider age range such as Stargardts, albinism, ROP (retinopathy of prematurity), among others.