Vision Rehabilitation
When you initially lost vision, you probably experienced a whole range of emotions, and after the shock wore off, you probably started to take stock of what you needed to do to continue your life. The following articles are written to give you more information about Vision Rehabilitation, so you can make the best choices for yourself.
What is Low Vision?
Despite major advances in health care and medical technology, many eye diseases can lead to low vision. Low vision is a reduction of central acuity or visual field loss (peripheral vision) that cannot be corrected with standard glasses, contact lenses, surgery or medical treatments. This loss of vision prevents the patient from performing desired tasks, such as reading the newspaper, writing a check or walking in an unfamiliar area.
The visually impaired person does not have to wait to become legally blind (visual acuity less than 20/200 or visual field less than 20 degrees) before seeking vision rehabilitation services, especially low vision services.
What is a Low Vision Exam?
It is a special type of examination that concentrates on identifying what you can see and that can be done with that vision.
A low vision exam is a through examination which determines residual functional vision in your eyes. It is performed by an Ophthalmologist or Optometrist who has a special interest in low vision and has received extra training in the area of visual impairment and low vision.
The first purpose of the examination is to determine the degree of functional visual ability – the amount of vision you have and are using at the present time, or could use with assistance and the right tools. This is done through extensive testing with sophisticated “State-of-the-Art” equipment to determine both the acuity (that vision used for reading and detail) and fields (peripheral or “side” vision).
Following careful measurement and evaluation of the valuable remaining vision, the second purpose of the low vision examination is to prescribe visual aids which will best enhance the residual vision. With the proper training, it is hoped that through the use of these aids one can continue the activities of daily living successfully and independently.
Why might this information be of benefit to you? Individuals who have low vision (best corrected visual acuity of less than 20/70) can frequently be helped to function better with low vision aids and a low vision examination is the process of identifying which aids would be most useful/helpful for a particular individual’s needs. Low vision aids fall in two categories:
- those that help with near vision tasks such as reading, and
- telescopic/distance aids.
Low Vision and Trade Offs
Reading/near vision aids include high power reading glasses, hand magnifiers, stand magnifiers and closed circuit televisions (CCTV’s). They generally range in strength from one (1) to sixty-eight (68) diopters. Almost anyone who has some residual vision can benefit from a low vision examination and can probably augment their vision enough with low vision aids to read some print. However, it is important to understand that using low vision aids always entails trade offs. When using reading aids, you trade off the ability to make out print, for the ease and convenience with which a person with 20/20 vision reads. The greater the degree of magnification it takes to read standard print, the greater effort it takes to read. A low power magnifier is generally fairly large in size and you can magnify several words at once, while a higher power magnifier will be significantly smaller in size and depending on its strength, you may only be able to magnify a few letters at a time.
The strength of the magnifier you need to see a specific size of print determines the magnifier’s size and ease with which you may read. For individuals who need a great deal of magnification to read, it may be easier to use a CCTV. Ultimately, only the individual involved can decide if he/she is able and willing to use a particular magnifier for reading. Many individuals find it more enjoyable to use talking books or radio reading services for the bulk of their reading and use low vision aids for those things which must be read by them. Whether or not you can benefit from low vision aids can best be determined by a low vision examination and your efforts to learn to use the aids prescribed.
What is a Closed Circuit Television Magnifier (CCTV)?
Individuals with a low vision problem can often use aids that have a combination of bright light and magnification to help make text readable. When the amount of magnification needed to read becomes very large, use of CCTV (Closed Circuit Television) magnification systems become especially useful, and can help some people regain what they thought was lost forever. These systems use television technology to capture and magnify print onto a monitor screen for viewing.
The basic operation of most of the different models of CCTV magnifiers are similar, and a typical system is described here. The system consists of a TV camera with a zoom lens, mounted on a stand, and uses a television to show the image. A lamp in the stand lights the area to be examined, and the material to be read is placed in the viewing area below the camera lens. A movable platform, called an X-Y Platform or a two-axis positioner, is used to move the material left and right, or toward and away from the user.
This allows text to be read along a line, and then moved from line to line. The magnification (size), focus (sharpness) and lens aperture (picture brightness) are all adjusted on the camera lens. Magnification in some systems can go as high as sixty (60) times, but generally it is best to use not more than twenty-four (24) times. This is because the very high magnifications only allow a very small amount of text to be seen at a time, and make it more difficult to adjust the positioner.
Telescopic Aids and Their Uses
Telescopic Aids are a type of Low Vision Aid whose function is to enhance the ability to see objects at a distance. Normally objects/things that cannot be seen with a reading aid, such as a magnifier. Typically, Telescopic Aids are used for watching TV, reading signs, identifying people and related tasks. A Telescopic Aid makes things at a distance appear much closer and consequently much larger, thereby enabling the visually impaired to discern greater detail than would otherwise be possible.
There are several types of Telescopic Aids, but they can be sorted into two broad categories. First, is the device monocular or binocular? Monoculars are used with only one eye and binoculars with two eyes. Second, is the device handheld or headborne? Handheld devices have to be held up to the eye to be used while Headborne aids are worn either on or in glasses or worn in lieu of glasses. Telescopic Aids vary tremendously in size and shape from the large field glasses most people are familiar with to the very small high-tech telescopes that are mounted in glasses lens that allow some visually impaired people to continue to legally drive.
Who will Telescopic Aids help? Generally, those who have some central vision remaining or vision in the area immediately surrounding the macula. Usually, if any telescopic device currently works for you, it is likely you would benefit from a Low Vision Exam to find the optimal telescopic aids for you.
Rehabilitation, “The Visual Aid Everyone Can Use”
Are you tired of saying, “I can’t do anything like I used to do” or “Everything is so hard since I lost some vision”? Try Rehabilitation – an old word but in a new area – Visual.
Visual Rehabilitation is for everyone who has an impairment or decrease in vision of any degree. As more and more people are receiving the diagnosis of macular degeneration as well as other problems that cause visual loss which cannot be corrected with regular glasses, visual impairment is entering the medical field to join the ranks of other physical disabilities, such as those caused by stroke or accident, which benefit from rehabilitation.
Rehabilitation does not focus on the amount of vision that is gone. It is a planned process that works with the functional vision that remains. Rehabilitation does not mean overcoming or curing an impairment. Rather, it means learning ways to use the remaining vision to its highest potential in meeting the challenges of every day living. It becomes an individual plan to use the strengths to their best advantage and remain realistic about the weaknesses. For some, rehabilitation may mean learning how to enjoy cooking again; for some, it may mean learning new ways to read, write and use the telephone; for others, it may mean help with traveling and getting places; and for some it may mean learning how to live safely, alone and independently as well as enjoying leisure activities. If there is anything a person used to do and can no longer do because of visual loss, rehabilitation shows the way through adaptation or the learning of new skills as it develops the potential of the remaining vision to fit one’s lifestyle.
So, before you make the assumption that difficulties which you experience as a result of vision loss are “something that comes with age” or “something that you have to get used to”, pick up your phone and call your physician to ask about visual rehabilitation.