Our eyes are the most obvious portion of our visual system. Any problem we encounter with our sight is usually attributed to our eyes. But they simply collect light from the world around us and send nerve impulses all the way to the occipital lobes in the back of the brain, where these impulses are translated into the images we see. If there is damage along that pathway, including cerebrovascular accidents (CVAs) or strokes, it may affect our perceptions in a variety of ways, even if central reading vision is still quite good.
An example is hemianopia. A stroke that afflicts one of the occipital lobes may cause a loss of half of one’s visual field (peripheral, or side, vision). Either the right or left side of both eyes is missing. A person can usually read single letters on an eye chart, but has difficulty reading sentences due to the inability to see full words or groups of words at one time.
Dysmetropia (some big names for these problems!) can be caused by certain strokes. It’s a set of symptoms that includes objects appearing smaller, larger, farther away, or closer than they really are. Palinopsia, a symptom of persistent images after the original object has been moved out of sight, also may follow CVAs.
A stroke in certain parts of the brain or inner ear may cause oscillopsia, a sensation that everything one views seems to be in constant motion. As with the rest of these unusual entities, the person may still demonstrate very satisfactory reading vision.
Prosopagnosia, resulting from strokes in the temporal and occipital areas of the brain, is a difficulty in recognizing faces. Even family and friends are strangers unless some other clue, like the person’s voice or familiar clothing, is enough to stimulate identification. This problem may be associated with topographical disorientation, in which people don’t recognize surroundings or landmarks and get lost very easily.
This small set of unusual visual perception problems illustrates the complexity of the eye and brain interactions. One of them, or many others not mentioned here, can become a great frustration despite one’s eyes performing their job perfectly.
BIO: Dr. Wymore, with Eye Surgeons Associates, is a board-certified general ophthalmologist. Dr. Wymore practices at our office in Rock Island, Illinois. For more information on Dr. Wymore, see his bio.
The material contained in this article is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health care provider.