The Lowdown on AMD and Low Vision

February is AMD/Low Vision Awareness Month! AMD, or age-related macular degeneration, is a progressive eye disease that affects the macula, the center portion of the retina. The retina is the layer of nerve tissue lining the back of the eye that converts light into electrical impulses, which the brain translates as visual images.

The macula is responsible for our sharp, clear central – or straight-ahead – vision, which is necessary for reading, driving, recognizing faces, seeing color and doing close-up tasks.

There are two main types of AMD: dry and wet. Most people, about 85 to 90 percent, have the dry type, which is characterized by the degeneration and thinning of macular tissue.

With dry AMD, which is the early stage of the disease, small, yellowish deposits of cellular material called drusen are often present under the macula. Typically, dry macular degeneration causes minimal problems with your eyesight, but you might notice some blurriness or blank spots in your central vision, and straight lines may appear wavy.

Dry AMD is generally detected during a routine eye exam, when your eye doctor can visualize the drusen. The doctor may also test for defects in your vision using an Amsler grid, a chart containing a series of horizontal and vertical lines. With AMD, the lines in the grid may look wavy or distorted.

There is no treatment for dry AMD. Your eye doctor may recommend you take a dietary supplement with a special combination of antioxidant vitamins and minerals (AREDS2 formulation), such as PreserVision or Ocuvite. AREDS2 supplements may help slow down vision loss due to AMD.

About 10 to 15 percent of people with dry AMD progress to wet AMD, which is the advanced stage of the disease. In wet AMD, abnormal blood vessels begin to grow in the back of the eye. These unstable blood vessels can leak fluid and blood into the retina and macula, which can damage the macula.

Symptoms of wet AMD include a distortion of vision (straight lines appear wavy), trouble reading or doing close-up activities in low light, decreased intensity of colors, blurriness of the printed word and a well-defined blind spot in your field of vision. Because AMD is progressive, symptoms generally get worse over time.

In addition to a thorough eye examination and testing with an Amsler grid, your eye doctor may use certain tests to diagnose wet AMD. These tests include fluorescein angiography, the use of a special dye and camera to look at the blood vessels in your eye, and optical coherence tomography (OCT), an imaging test that takes clear, cross-sectional pictures of your retina.  

Fortunately, there are treatments for wet AMD that can slow down or stop vision loss. The primary treatment is injections of an anti-VEGF medication, which interferes with the formation of blood vessels. Another, less common treatment is photodynamic therapy, which involves the use of a light-sensitive medication that is activated when exposed to a laser.

AMD can lead to low vision, vision loss that cannot be corrected with prescription glasses, contact lenses, medication or surgery, although these treatments may help you to see better. Other eye conditions, such as glaucoma, retinitis pigmentosa and eye cancer, as well as disorders such as diabetes and stroke can also cause low vision.

Low vision, which is typically defined as a visual acuity of 20/70 or poorer, can affect your central or peripheral vision. People with low vision must learn to adjust to their condition. If you have low vision, you may benefit from using low vision aids, such as magnifying glasses, hand-held magnifiers and large-print versions of reading materials.

Your eye doctor may refer you to a specialist in vision rehabilitation. Vision rehabilitation begins by recognizing the challenges of vision loss and making adjustments to maximize what vision you have left. It’s a process of learning how to do tasks, such as reading and writing, in news ways that keep you as independent as possible To maintain your best possible vision, see your eye care specialist routinely for a complete eye exam.