Q: Is there any way to prevent macular degeneration?
A: Doctors aren't sure how to prevent macular degeneration. Research suggests that ultraviolet light (and possibly blue light) factors into the problem, so sunglasses could be very beneficial. What you eat also affects your macula. Researchers know that antioxidants (vitamins A, C and E), zinc, lutein, zeaxanthin and essential fatty acids all can aid in preventing and slowing down macular degeneration. Read more about nutrition and eye health. Ask your doctor about recommended nutritional supplements. Exercising and quitting smoking might also be helpful.
Q: What exactly does "20/20 vision" mean?
A: "20/20 vision" is commonly accepted as the standard of normal distance vision for a human being. Basically it means "good visual acuity at 20 feet." So if your vision is 20/20, you can read certain sizes of letters on a Snellen chart clearly at 20 feet or closer. But if your friend has 20/15 vision, his visual acuity is better than yours: you would have to stand 15 feet away from the chart to read the smaller letters that he can read while standing 20 feet away. Conversely, someone with 20/30 vision has worse distance vision than you. By the way, visual acuity at a distance isn't the only measure of how good your vision is. You could have 20/20 distance vision but still have difficulty seeing at night because of poor contrast sensitivity. Or you could have near vision problems because you're over 40 and experiencing presbyopia.