what is vision loss?
Vision loss or low vision is commonly known as an impairment of vision, caused by disease and not part of the natural aging process. It is also characterized by impairment of both eyes to an extent that causes a person to lose the ability to perform day to day activities such as reading, driving, or recognizing faces. Many individuals experience vision loss at different rates in each eye, which may allow them to function quite normally with one eye until the second eye begins to lose function as well.
HOW DOES VISION LOSS OCCUR?
Vision loss occurs when a part of the eye is damaged by disease or abnormality. Depending on the specific eye disease, functional vision can be impaired in different ways. Vision loss can occur at any age, even from birth due to congenital diseases such as congenital glaucoma or cataracts. Vision loss in mid-life can be caused by diseases such as diabetes or glaucoma. There are also rare inherited retinal diseases such as Stargardt disease or Retinitis Pigmentosa that present from pages 20-50. Later in life, a person may develop age-related vision impairment. Age-related eye diseases are the most frequently occurring problems overall, with age-related macular degeneration (AMD) being the number one cause of vision loss of those over age 65 in all developing countries around the world. Eye diseases such diabetic retinopathy, glaucoma and inoperable cataracts can also be prevalent in ages 50 and above.
What are the most common types of vision loss in adults?
The most common impairments occur by the loss of central vision, while other diseases cause the loss of peripheral vision. There are still other eye diseases that can cause an overall obscurity of the vision, or an impairment of parts of both the center and peripheral vision.
- Central vision loss usually occurs from damage to the area known as the macula, the very center of the retina. Some diseases only affect the macula, while others can damage other parts of the retina. Vision loss rarely occurs at the same rate in each eye; that is, one eye may not be affected for quite some time while the other sustains significant damage.
- Peripheral vision loss can leave a patient with only central vision, a condition sometimes called tunnel vision. Side vision can be lost slowly over time with minimal loss of functionality. At more advanced stages of these diseases, functional vision can become significantly impaired. Night vision is also sometimes lost with peripheral vision damage.
In some eye diseases, both the center and areas of the side vision can be affected or damaged, again, usually not at the same rate.
There are other common problems that occur with many types of eye conditions such as sensitivity to light, reflections and glare. Still other problems affect may affect focus or contrast. Letters or words become not only difficult to read, but may look gray or faint instead of dark or black, for instance. The ability to distinguish between different colors (color deficiency) may also occur. Some diseases affect dark adaptation, or the ability of the eyes to adjust between light and dark environments.
Age-related macular degeneration
Age related macular degeneration (AMD) is a disease of the central area of the retina, called the macula. The macula is responsible for sharp, central vision. It can be a very slowly progressing problem, and in its later stages can rob a person of a great portion of their central vision. Macular degeneration does not affect the peripheral vision.
Macular degeneration is the most frequently occurring eye disease in persons over age 65. The incidence is 1 in 6 persons over age 65, 1 in 5 persons over age 75, and for those 85 years of age or older as many as 1 in 4 are affected.
In the early stages, persons may not know that macular degeneration is beginning. Yearly eye exams are important to maintain the health of your eyes. Seeing a retina specialist is important as they have special imaging equipment to diagnose and recommend how often to monitor the problem.
Requesting a medical summary letter for yourself and your family is very important. You should make your own medical file and keep it for future reference, as it may be needed later when seeking new vision rehabilitation services
The letter should include the visual acuity measurement of each eye, a description of the appearance of the retina, and the appearance of the macula. The letter should include the diagnosis, any treatments that were recommended or given, tests performed as well as a prognosis. This should be requested after each eye appointment with the retina specialist.
You should also talk with your specialist about ways to monitor your own vision. If discovering a change, find out who to call and what steps should be taken.
Here are some useful questions to ask during eye exams:
- How does the retina look?
- Do I have any drusen?
- Are the drusen small or large?
- Do I have more drusen than the previous year’s appointment?
- What is the appearance of the macula?
- Are there any signs of abnormal blood vessel growth under the retina?
If abnormal blood vessel growth begins under the retina, this is known as going from the dry form of macular degeneration to the wet form. These new abnormal blood vessels can leak fluid or blood.
The wet form can be treated if caught early with an injection of anti-blood vessel growth factor. Your retina specialist will then closely monitor the treatment and recommend further treatment protocols for you. Treatment can be very helpful for many in keeping the disease stable.
During any stage of macular degeneration, it is highly recommended to seek low vision services. Research has shown early intervention in learning to use vision aids and devices can prevent patients from becoming discouraged or depressed. Learning new skills at the earlier stage of macular degeneration and learning to function with vision aids helps to avoid much greater adjustments in the future.