Vision Problems Associated With Alzheimer's Disease

Few people know that impaired vision and Alzheimer's disease--both commonly associated with the elderly--are actually related. The Alzheimer's Association reports that over 60 percent of Alzheimer's patients experience a decline in at least one visual capacity.

Perception

• Alzheimer's disease causes vision impairment not by affecting the eye, but the brain. Patients have difficulty perceiving what they see in terms of motion, depth and color, rather than problems with clarity.

Motion

• Drs. Charles Duffy and Sheldon Tetewsky at the University of Rochester (New York) Center for Visual Studies published research in 1999 on the "motion blindness" observed in Alzheimer's patients. They discovered patients did not see fluid movement but instead perceived the world as a series of still frames. The doctors theorized that this stop-and-go view of the world causes patients' disorientation, even in a familiar setting.

Depth

• Alzheimer's patients may also lack depth perception, causing three-dimensional objects to appear flat like drawings. This can make shadows look like holes, causing fear or confusion for those with dementia.

Color

• Color perception declines with age for everyone, but Alzheimer's patients exhibit a greater loss in the blue-violet range, making blues, blue-greens and blue-violets look the same. Red stands out the most, making red items easier for dementia patients to see.

Value

• Dr. Peter Rosen of the Sharp Rees-Stealy Medical Group of San Diego, California, says screening for vision impairment aids early detection of Alzheimer's, slowing the disease's progress.