Because the brain controls all the body’s functions, symptoms of a traumatic brain injury can vary greatly. According to Brainline, 20% to 40% of brain injury patients experience vision disorders.
The types of vision disorders that result from brain injuries depend on the specific damage. Here are some conditions that patients are likely to experience.
One situation in which a brain injury can result in blindness is if the damage occurs at the back of the head. This is the location of the brain centers that process visual data. In this scenario, the eyes may be completely normal and functioning, but there is a disruption in the communication system between the eyes and the brain, rendering the latter unable to process the information that it receives.
Loss of visual acuity
Visual acuity refers to the clarity or sharpness of the images perceived. Many people lose visual acuity to natural causes and compensate with corrective lenses. A brain injury can result in a traumatic loss of visual acuity. Depending on the extent of the damage, it may be possible to correct this with glasses. Otherwise, magnifiers or electronic reading aids may be necessary.
Loss of visual field
The visual field refers to everything a person can see without turning his or her head and while focusing the eyes straight ahead. It is approximately 95 degrees on either side, 70 degrees up and 80 degrees down. A brain injury can reduce the visual field so that a portion becomes fuzzy to the point of imperceptibility. The most common types of visual field loss to occur from brain injuries are quadranopsia, in which a patient loses a quarter of the visual field, and hemianopsia, in which a person loses half of the visual field on either the left or the right.
Sometimes a patient who loses vision in part of the visual field retains awareness of what he or she cannot see, which makes it easier to learn compensatory strategies to make up for the vision loss. Other times, the injury affects perception as well as vision. Visual field loss with neglect occurs when the patient has no awareness of what he or she cannot see. Compensating for this type of loss is more difficult.