Hemianopsia (Hemianopia)

"It is in the brain that the poppy is red, that the apple is
odorous, that the skylark sings."

- Oscar Wilde

A homonymous hemianopsia is the loss of half of the field of view on the same side in both eyes. It is also referred to as a homonymous hemianopia. It occurs frequently in stroke and traumatic brain injuries due to the way part of the optic nerve fibers from each eye crossover as they pass to the back of the brain. The visual images that we see to the right side travel from both eyes to the left side of the brain, while the visual images we see to the left side in each eye travel to the right side of the brain. Therefore, damage to the right side of the posterior portion of the brain can cause a loss of the left field of view in both eyes. Likewise, damage to the left posterior brain can cause a loss of the right field of vision. The most common causes of this  damage include stroke, brain tumor and trauma.

A homonymous hemianopsia can steal a patient’s independence. Patients report fear of running into objects, tripping, falling, knocking over drinks, and being startled by objects or people that suddenly appear out of nowhere. Patients may become so fearful of falling or running into objects that they may be unwilling to travel or shop without assistance. Panic attacks may even occur when in crowded stores, because homonymous hemianopsia patients can easily become lost, feel disoriented and unable to navigate safely through the crowd. Patients often loose their place while reading. Some patients fearing both embarrassment and the danger of injury may continue to withdraw socially.

Our side vision allows us to distinguish approaching objects and people in an almost unconscious way. When a moving car passes in front of us, we are not alarmed, because we detected and sensed it was coming. When we lose part of our side vision from a hemianopsia, objects suddenly appear, often startling the patient. The patient may feel unsafe and even overwhelmed in crowded areas.

Patients may mistakenly believe that the loss of vision is just in one eye. They may report “my right eye has been bad since the stroke”, while actually the damage in the brain caused a loss in both eyes. Hemianopsia patients also routinely fail to fully report the degree of their visual disability. It is not uncommon that patients will deny the loss of visual field and report no problems, while caregivers observe them running into objects, tripping, and being startled.

Homonymous hemianopsia can occur in isolation, but in most cases the patient will experience  other problems that may impact rehabilitation and the return to a "normal" life.  An important part of the process of helping the hemianopsia patient is to also detect and treat the cluster of problems that may be associated with brain injury.

Therapy to develop scanning eye movements and new types of visual field expander lenses are helping patients return to a more normal life. Within www.hemianopsia.net you will learn about the latest options available to help hemianopsia patients.

The Low Vision Centers of Indiana

Richard L. Windsor O.D., F.A.A.O., D.P.N.A.P.
Craig A. Ford O.D., F.A.A.O.
Laura K. Windsor. O.D., F.A.A.O.
Ali E. Prible, O.D.