Hemianopsia

Overview

Hemianopsia, also known as hemianopia, is a type of visual field loss that occurs on the same side in both eyes. This condition can be a result of various medical conditions, including stroke, brain tumor, or traumatic brain injury. Hemianopsia can significantly impact a person's quality of life, affecting their ability to read, drive, or navigate their environment.

A photograph showing a person's perspective with hemianopsia. The left half of the image is blacked out, representing the loss of vision on one side.

Causes

Hemianopsia is most commonly caused by damage to the visual pathway in the brain. This damage can occur due to a variety of conditions, including stroke, brain tumor, traumatic brain injury, or brain surgery. The location of the damage within the visual pathway determines the type and extent of the visual field loss.

Types

There are several types of hemianopsia, each characterized by the area of the visual field that is affected. These include:

Homonymous hemianopsia: This is the most common type of hemianopsia, characterized by visual field loss on the same side in both eyes. It is typically caused by damage to the visual pathway in one hemisphere of the brain.

Binasal hemianopsia: This type of hemianopsia is characterized by visual field loss on the inner (nasal) halves of both eyes. It is typically caused by damage to the optic chiasm, where the optic nerves cross.

Bitemporal hemianopsia: This type of hemianopsia is characterized by visual field loss on the outer (temporal) halves of both eyes. It is typically caused by damage to the optic chiasm.

Quadrantanopsia: This type of hemianopsia is characterized by visual field loss in one quadrant of both eyes. It is typically caused by damage to a specific part of the visual pathway in the brain.

Symptoms

The primary symptom of hemianopsia is the loss of half of the visual field in both eyes. This can manifest in a variety of ways, depending on the type of hemianopsia and the extent of the visual field loss. Some people with hemianopsia may not be aware of their visual field loss, especially if it is mild or if they have adapted to it over time. Other symptoms can include difficulty reading, problems with depth perception, and difficulty navigating the environment.

Diagnosis

Hemianopsia is typically diagnosed through a visual field test, which measures the full extent of the visual field. This test can help to identify the type and extent of the visual field loss, as well as the likely location of the damage within the visual pathway. Other diagnostic tests may include a CT scan or MRI to identify the underlying cause of the hemianopsia.

Treatment

Treatment for hemianopsia is primarily aimed at addressing the underlying cause of the condition. This may involve medical or surgical treatment for conditions such as stroke, brain tumor, or traumatic brain injury. In some cases, visual rehabilitation may be recommended to help individuals adapt to their visual field loss. This can involve strategies such as eye movement training, visual field expansion devices, and compensatory techniques.

Prognosis

The prognosis for hemianopsia depends on the underlying cause of the condition. In some cases, the visual field loss may be temporary and improve over time, especially if the cause of the hemianopsia is addressed. However, in other cases, the visual field loss may be permanent. Regardless of the prognosis, individuals with hemianopsia can often benefit from visual rehabilitation to help them adapt to their visual field loss and improve their quality of life.