Dr. Xinzhi Zhang of the Centers for Disease Control and Prevention said vision, like a lot of things, is less sharp as people age, but there's a difference between normal aging and things going wrong.
''Some vision problems are a normal part of aging, like having trouble reading small print in a newspaper and those can be corrected with glasses," Zhang said in a statement. "However, many serious vision problems are caused by age-related eye diseases.''
These include cataracts, glaucoma, macular degeneration and diabetic retinopathy, which is related to diabetes and could be prevented, along with diabetes, through weight control with proper diet and physical activity, Zhang said.
Cataracts, cloudy areas in the lens, are another common eye problem that can come with age. Half of those who reach age 80 are expected to have cataracts. There are no specific steps to prevent cataracts, but tobacco use and exposure to sunlight raise the risk of developing them, eye specialists advise.
Glaucoma comes from increased fluid pressure inside the eye that damages the optic nerve. It can slowly steal peripheral vision and it might not be noticed until it is advanced, but it can be treated with prescription eye drops, lasers or surgery, the National Institute of Health said.
Scientists found people who eat diets rich in green, leafy vegetables -- such as kale and spinach -- or fish are less likely to have advanced age-related macular degeneration. A specific combination of vitamins and minerals can prevent the eye disease from progressing to a more severe form.