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What Is Partial Hemianopia?

Medically Reviewed by Dan Brennan, MD on May 11, 2021

Hemianopia is when you lose sight in half of your visual field. This condition is not a problem with your eyes. It occurs after a stroke or other brain injury.

What Are the Types of Hemianopia?

The type of hemianopia you have depends on which part of the visual field you lost vision in and whether it affects both eyes the same way.

Homonymous hemianopia. This is the most common type of hemianopia. It can affect different parts of your visual field. But the affected part is the same in each eye. The types of homonymous hemianopia include:

  • Right hemianopia, which causes a loss of vision in the right half of each eye
  • Left hemianopia, which causes a loss of vision in the left half of each eye
  • Superior hemianopia, which causes a loss of vision in the upper half of each eye
  • Inferior hemianopia, which causes a loss of vision in the lower half of each eye

Heteronymous hemianopia. This type of hemianopia is caused by a lesion on your optic chiasm. This is the area in your brain where the optic nerves cross and form an “X.” The two types of heteronymous hemianopia are bitemporal and binasal. Bitemporal hemianopia is when you lose vision in the outer half of each eye. Binasal hemianopia is when you lose vision in the inner half of each eye.

What Are the Symptoms of Homonymous Hemianopia?

The symptoms of hemianopia can range from mild to severe. Hemianopia can be complete or partial. You may not realize what the problem is when you have hemianopia. If you have right hemianopia, you may feel like the problem is with your right eye. If you have left hemianopia, you may think the problem is with your left eye.

Here are some additional symptoms of hemianopia.

Not noticing things on the affected side. You might bump into things on the affected side. Driving may be difficult since you can't see cars or other objects on that side. You may not notice objects on a table on that side. You may only be able to read the right or left half of a page. Walking in crowds or crossing the street can be dangerous.  

Visual hallucinations. This may happen if your hemianopia develops as suddenly as it would with a stroke. This is not a psychiatric issue. You should tell your doctor if you've had hallucinations.   

Visual neglect. This happens when you don't even try to move your head or eyes to see what's on the affected side. You might leave half of your meal uneaten or not turn to see what's on the other side of the table.   

Hemianopia can be complete or partial. With partial hemianopia, there may be a difference in the clarity or brightness of objects on one side of your visual field. 

What Are the Symptoms of Heteronymous Hemianopia?

Heteronymous, or bitemporal, hemianopia doesn't cause the problems that homonymous hemianopia does. Bitemporal hemianopia may only cause problems in your depth perception or a slight loss of peripheral vision. You can often still get a driver's license with bitemporal hemianopia in many U.S. states.

Binasal hemianopia is extremely rare. You may not have significant symptoms related to your vision. You might have some blurry vision or a loss of color vision. Your vision may also be normal. 

Binasal hemianopia is more likely to be caused by problems relating to your eyes such as glaucoma than by problems in your brain. But it can still be caused by problems with your brain.

What Causes Hemianopia?

Hemianopia can be caused by any condition that affects your brain or optic nerves, including:

How Is Hemianopia Treated?

The treatment for your hemianopia will depend on its cause. The chances of recovery are better if your hemianopia is caused by a tumor or inflammation rather than a stroke. Your treatment plan may focus on reading and dealing with the environment. Some options for treatment include:

  • Mirrors or prisms on glasses to help you see the missing visual field
  • Training yourself to make quick movements toward the affected side
  • Learning to consciously look toward the affected side to see more of the environment
  • Using a straight edge to direct your eyes when you're reading
  • Playing games and do crossword puzzles to help with coordination
  • Walking with a partner on your affected side to help guide you
  • Using a driving simulator to determine if you'll be able to drive again

Show Sources

SOURCES:

AMERICAN ACADEMY OF OPTOMETRY: "Binasal Hemianopsia: A Clinical Anomaly."

Beth Israel Lahey Health Winchester Hospital: "Hemianopsia."

Cleveland Clinic: "Homonymous Hemianopsia."

North American Neuro-Ophthalmology Society: "HOMONYMOUS HEMIANOPSIA."

Ophthalmic and Physiological Optics: "Bitemporal hemianopia; its unique binocular complexities and a novel remedy."

rsb: "Homonymous Hemianopia."

StatPearls: "Neuroanatomy, Bitemporal Hemianopsia."

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