Low vision is defined as a partial vision loss that cannot be corrected with lenses, surgery or other means. A person with low vision has severely reduced visual acuity or contrast sensitivity, a significantly obstructed visual field of vision or all three. Signs of low vision include difficulty recognizing a familiar face, difficulty reading and/or difficulty seeing objects and potential hazards like steps, curbs, walls, uneven surfaces and furniture. Low vision includes a wide spectrum of vision loss, but most people retain some usable vision. Low vision rehabilitation includes a combination of learning to use the remaining vision and learning compensatory techniques for safely navigating through life with limited vision.
Normal Changes in the Aging Eye
Beginning at age 40-50 almost everyone experiences presbyopia. The result of the eye’s lens losing elasticity, presbyopia makes it harder to focus for up close tasks like reading. While it is an annoyance, this nearly universal change is easily corrected with reading glasses or bi-focal lenses. The lens of the eye becomes more dense and yellow with age. These changes can affect the perception of color and contrast sensitivity. For instance, dark blue and black may appear similar and difficult to differentiate from one another. In addition, it may become harder to see where an object ends and another begins, making it difficult to see curbs and steps, for example. As the eye ages the pupil gets smaller and consequently lets in less light. The result is that one needs more light to read or do other tasks. In addition, accommodation to changing light conditions takes a bit longer, as in, for example, going from a bright day into a dark theatre.
Conditions that cause low vision
Cataracts are a clouding of the lens of the eye. The consequences of cataracts include blurred vision, difficulty differentiating color and increased glare. Cataracts can be corrected by surgical implantation of a new lens. For those who are not surgical candidates, corrective lenses can help with some of the problems related to cataracts.
Glaucoma is a cluster of conditions, all of which cause some damage to the optic nerve. The most common form, known as Open Angle Glaucoma, occurs when there is increased pressure in the retina of the eye. This pressure causes damage to the optic nerve and the result is subtle loss of contrast, difficulty driving at night and eventually a loss of peripheral vision. Glaucoma does not have any symptoms, so can go undetected if yearly eye exams are not performed. The treatment is eye drops and in some cases surgery to relieve the pressure.
A result of long standing diabetes, diabetic retinopathy causes retinal damage which results in dark spots in the visual field. Nearly half of all persons with diabetes are affected by diabetic retinopathy. It is imperative that diabetics have regular eye exams so that problems can be identified early. Laser treatments can help to minimize damage and preserve sight as long as possible.
While not a normal part of aging, macular degeneration is age related. In addition to advancing age, risk factors for developing macular degeneration include many poor lifestyle habits like smoking, high sugar and fat intake, sedentary lifestyle and smoking. Damage to the macula, which is the central part of the retina, causes a loss of central vision. 90% of those with macular degeneration have the “dry” type which progresses slowly. The other 10% of people have the “wet” type, so named because it is characterized by leaky blood vessels that cause blood to leak under the macula. Wet macular degeneration can cause rapid loss of vision and be more severe than the dry type.
If you have low vision
If you have recently been diagnosed with low vision, do not despair. While the loss of sight is a major life event and represents a loss, there is help available to assist you in living a fulfilling life. First, find a doctor who specializes in low vision. Many optometrists and ophthalmologists do not have this specialized training. A doctor who specializes in low vision can prescribe magnifying lenses to assist you with daily tasks. After finding a low vision specialist, seek out low vision rehabilitation. Through the rehabilitation process, you will find that there are many ways to compensate for your vision loss and do things you have always done in a new way. Talk with an Occupational Therapist, they can assist you with many of the activities of daily living and help you find the right resources. There are many, many auditory adaptive devices available to assist those with low vision deficits, things like talking clocks, scales, telephones, thermometers, books and so many others. There are also tactile devices that can help with navigation in the kitchen, matching your clothes, writing a check and identifying your mailbox to name a few.
If you do not have low vision
It is important to have an annual eye exam so you can be monitored for the above conditions, which may not have early warning signs. Also, live a healthy life by not smoking, eating right and getting 30 minutes of movement each day.
Assisting a person who has low vision
You are sure to live in close proximity to someone who has low vision. Here are a few tips for ways you can be of assistance to them.
When you approach a person with low vision, greet them and say your name so they can recognize you.
Ask if the person would like assistance (sometimes they may not and that is fine!)
If the elevator in your building does not talk, let them know what floor you are on.
Help them to read the menu at dinner.
Volunteer to read their mail to them.
If you are leading them, allow them to take your arm at the elbow and follow you. Do not try to pull them along. Pause briefly near stairs or curbs.
Serve them a drink or snack at a gathering.
Help them to play bingo or other games that require sight.
If you have a low vision support group in your community, ask the person who leads it if there are other ways that you can be of assistance.