What Is Hemianopia?

Hemianopia is a blindness or reduction in vision in one half of the visual field due to damage of the optic pathways in the brain. This damage can result from acquired brain injuries caused by stroke, tumor or trauma.

A graphic simulation of Hemianopia comparing a normal street scene, and the same street scene viewed under the simulated effects of Hemianopia

Stroke occurs when there is damage to a group of nerve cells in the brain often due to interrupted blood flow, caused by a blood clot or blood vessel leaking. Depending on the area of the brain that is damaged, a stroke can result in coma, paralysis of one side of the body, speech and vision problems, and dementia.

What Are the Different Types of Hemianopia?

The most common defect, right homonymous hemianopia, occurs in corresponding halves of the right field of vision. It can also occur in corresponding halves of the left field of vision (left homonymous hemianopia), in the upper half of the field (superior hemianopia), the lower half (inferior hemianopia), or both outer halves of the field (bitemporal hemianopia). In hemianopia, half of the field is blanked out on both eyes.


  • Loss of half of the field of vision

  • Decreased night vision

  • Need for more light

Risk Factors

Whoever may be at risk for stroke is also at risk for hemianopia. People with high blood pressure or those with an abnormal heart rhythm, which is associated with blood clots in the heart, may be at risk for stroke.

Age is also a risk factor, as the majority of people who experience stroke are over the age of 55.

What You Can Do to Reduce Risk

Reducing the risk of stroke will reduce the risk of hemianopia. For more information on how to reduce your stroke risk, visit the National Stroke Association.


Though there is no specific medical or surgical treatment for hemianopia, one's effective use of vision may improve over time. In addition, there are optical devices that may be helpful in increasing the field of vision. Some examples include field-expanding prism lenses and magnifiers.

Following diagnosis of hemianopia, it is also important to receive a careful evaluation by a low vision specialist who can prescribe optical prism glasses and other devices, as well as recommend vision rehabilitation services. Vision rehabilitation specialists can teach people with hemianopia to maximize their existing sight by increasing lighting or using adaptive devices, for example.



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