QUESTION

What are the causes of low vision?

ANSWER

“Low vision” is a term that covers significant visual impairment, from vision that can’t be corrected to better than 20/40 even with prescriptive lenses (eyeglasses or contacts), surgery or medication…to vision that is 20/200 or worse even with correction, defined as legally blind. About 6.5 million seniors (people age 65 and older) in the US have low vision—a number that is expected to double over the next 30 years, according to a study from Johns Hopkins University. What’s driving the increasing numbers? Most of the conditions that lead to low vision are age-related…and our population is aging. The most common causes of low vision include…

  • Macular degeneration: Deterioration of the center of the retina (macula), the area most critical for focusing and seeing. Macular degeneration causes “blind spots” directly ahead, with vision loss expanding as the condition progresses.
  • Glaucoma: An increase in eye pressure that damages the optic nerve, leading to vision loss and sometimes blindness. Unlike vision loss that comes with macular degeneration, vision loss with glaucoma starts at the periphery, or edges, of your field of vision, often without any symptoms until the condition is advanced.
  • Diabetic retinopathy: Damaged blood vessels in the retina caused by long-term, uncontrolled high blood sugar in people with diabetes. The tiny vessels swell and leak fluid, damaging the delicate retina. There may be no symptoms…or increasing “floaters,” blurry vision, blank areas in the field of vision, poor night vision and/or a faded appearance to colors. Diabetic retinopathy also is associated with neovascular glaucoma, a rare and hard-to-treat form of the disease.
  • Cataracts: Clouding of the lens on the front of the eye, which focuses light onto the retina. The clouding is the result of proteins in the lens clumping together, giving the lens a milky appearance. Besides cloudy vision, cataracts can interfere with night vision and, if left untreated, are a leading cause of blindness.