Ageing and Eyes: Low Vision
Low Vision Does not Have to Limit You
This is the third of four articles on health issues pertain to vision loss. All of these problems are preventable. Low vision is decreased eyesight that cannot be corrected with eyeglasses, contact lenses, or surgery. The person with low vision is not blind but may have eyesight loss that ranges from blind spots, poor night vision, glare problems, to nearly fully loss of eyesight. Adult visual acuity is 20/20 or 20/40. A visual acuity of 20/20 means that you can see an object clearly standing 20 feet away from it. The American Optometric Association lists two categories of low vision
1. Partially sighted: This person has visual acuity between 20/70–20/200 while wearing prescription eyeglasses or contact lenses. Visual acuity of 20/700 means that you must stand no more than 20 feet away from the object to see it while a person with sharp vision can see the same object clearly at 70 feet.
2. Legally blind: A person that is legally blind has eyesight of 20/200 with eyeglasses or contact lenses and/or a restricted vision field that is less 20 degrees wide. A legally blind person may be able to see shadows or shapes of people or objects or but not clearly and have loss of peripheral vision. Legally blind people cannot drive.
Low vision includes problems such as
1. Loss of central vision because of a blind spot. Central vision is the vision when you look forward. Put your hands on the side of your face near your eyes to block out your side vision. All that remains is central vision.
2. Loss of peripheral vision. Vision on the side, below, or above eye level. Now move your eyes toward the right and left, up and down.
3. Night blindness
4. Blurred vision
5. Hazy vision
Low vision can be caused by several things or a combination of problems. The three most common causes of low vision are diabetes, age-related macular degeneration, and glaucoma. Other causes of low vision include eye cancer, albinism, brain trauma, retinitis pigmentosa or other familial eye disorders. IF you have a family history of or have been diagnosed with any of the above eye disorders you are at risk of developing low vision or going blind. You do not have to get low vision or blindness. Prevention is the key.
Tips for Preventing Low Vision
1. Get an eye examination at least every two years
2. Have a glaucoma test as part of the eye examination.
3. Use eye protection methods when outside in the sun
a. Wear a cap with a bib
b. Wear sunglasses with ultraviolet protection
4. Keep your blood glucose level under control if you are diabetic, which is less than 130 mg/dl and no more than 180 mg/dl at eating. If not diabetic, your blood glucose should be between 70–99 mg/dl except for after eating which could get up to 140mg/dl.
Most people who develop low vision and as they age will use products that aide their vision. They may start by using non-optical devices such as
1. Large print books, clocks, telephone, or other devices
2. Increase the font size on their computer or laptop.
3. Increase the lighting in their house
4. Color-coded pill boxes
5. Text reading software
6. High contrast or talking clocks or watches
7. Large felt-tip pins or markers and wide-lined paper for writing notes.
8. Signature guides
9. Wallets that separate deferent bill denominations into different compartments
As their vision decreases even more, they may use optical vision devices such as
1. Telescopic glasses: placed on top of eyeglasses
2. Lenses that filter light
3. Magnifying glasses
4. Hand magnifiers
5. Video magnifiers
6. Text to voice devices like OrCam Read
7. Reading prisms: these eyeglasses refract light rays before entering the eye and may shift images away from the optical center point to a better position that allows the light to hit the retina in the right place.
Remember, people who are legally blind, visual acuity of 20/200, cannot drive. People who have low vision of 20/70 may be able to drive but may be restricted to driving in the daytime only, may have to wear bioptic or telescopic eyeglasses, take a low vision driver education course, or have special modifications on their vehicle.
References:
What is Visual Acuity? (Tests, Charts & Scores Explained). Available at
https://www.visioncenter.org/resources/visual-acuity-score/.
Low Vision. Available at https://my.clevelandclinic.org/health/diseases/8585-low-vision
Low vision aids for reading and daily living. Available online at
