There are numerous types of hemianopia, each named depending on the region of the visual field that is affected, as well as the size of the affected area. Below is an overview of some of the most common vision problems affecting victims of stroke and brain injuries.

Homonymous Hemianopia / Hemianopsia

The most common type of hemianopia among survivors of stroke and brain injury is right homonymous hemianopia. This vision defect is characterized by low vision or blindness in corresponding halves of the right field of vision. Likewise, left homonymous hemianopia is characterized by low vision or blindness in the left field of vision in one or both eyes.

Quadrantanopia (Quadrantanopsia / Quadrantic Hemianopia)

Quadrantanopia - Pre VRTQuadrantanopia is a specialized type of hemianopia. It is characterized by low vision or blindness in one quarter of the visual field. Like hemianopia in general, quadrantanopia is often homonymous; that is, low vision or blindness occurs in the same quadrant of each visual field. For example, someone who suffers upper (or superior) homonymous quadrantanopia will experience vision loss in the upper quadrant of the visual field of each eye.

Less Common Types of Hemianopia

In addition to homonymous hemianopia, other types of hemianopia include the following:

• Superior hemianopia: the upper half of the field of vision is affected
• Inferior hemianopia: the lower half of the field of vision is affected
• Bitemporal hemianopia: both outer halves of the field of vision are affected

In addition, hemianopia and quadrantanopia can be congruous or incongruous. If hemianopia is congruous, the visual fields of each eye have identical defects. If hemianopia is incongruous, the visual defects of each eye are affected in different ways.

Finally, hemianopia can be bitemporal. This means that the temporal (outside) halves of the visual field are affected, leading to tunnel vision, which is characterized by a loss of peripheral vision.

“Homonymous” means that vision loss is present in the inside edge of one eye – the side closest to the nose – and the outer portion of another. This type of vision loss is a common sign of stroke and brain injury. The question is, why do hemianopia and quadrantanopia involve such distinctive patterns of vision loss?

The answer lies in the brain. When a stroke or brain injury patient experiences vision loss, it is a sign of optic nerve damage, not damage to the eyes. In other words, vision loss occurs when the optic pathways to the brain are damaged during a stroke or brain injury. Because of how the brain’s visual system is wired, vision loss after a brain injury often occurs in homonymous portions of each eye’s visual field.

The main symptom of hemianopia is vision loss in half of the field of vision (whereas quadrantanopia affects a quarter of the visual field). Vision loss may range from slight to severe. In addition, patients may experience decreased night vision and a need for more light, especially when reading.

Patients suffering from hemianopia or quadrantanopia may run into objects, trip or fall, knock things over, lose their place when reading, or be surprised by people or objects that seem to appear suddenly out of nowhere. They may become afraid of venturing out in public, often because they easily get lost lost in crowded areas.

In addition, some hemianopia and quadrantanopia patients experience visual neglect; that is, they may be unaware that they cannot see to one side. They may orient their body to compensate, bump into objects on the affected side, or miss parts of words when reading. It is also common for those affected by hemianopia or quadrantanopia to believe that they have vision loss in only one eye.

A skilled clinician can effectively diagnose the type and extent of hemianopia or quadrantanopia, then plan a course of hemianopia rehabilitation.

In some cases, hemianopia and quadrantanopia spontaneously resolve within the first three months after a stroke or brain injury. Traditionally, vision loss that remained after the period of spontaneous recovery was considered untreatable. Fortunately, new research in neuroplasticity – the brain’s self-repair mechanism – has led to key advances in hemianopia rehabilitation that allow patients to improve long after spontaneous recovery has concluded.

Vision Restoration Therapy uses special patterns of stimulation designed to help the brain heal itself beyond what has been accomplished during spontaneous recovery. This method of hemianopia rehabilitation may help regardless of how long ago the injury occurred.

Learn about types of visual field deficits, how vision rehabilitation post stroke or brain injury works, and much more by browsing our website, emailing NovaVision Patient Services, or by calling 1.888.205.0800.