Astereopsis caused by traumatic brain injury.

Impaired depth perception (astereopsis) has been observed in a variety of cerebral pathologies affecting the posterior parietal lobe. In the current study of 93 consecutive head trauma admissions, 24% had complete astereopsis and 41% performed more than 2 SDs below the orthopedic control group mean. Degree of impairment was related to Glascow Coma Scale score, length of posttraumatic amnesia, reduced visuospatial and memory abilities, and the presence of intracranial pathology of the parietal lobes. Impairment was also related to trauma severity in patients without any visualized intracranial pathology, presumably due to diffuse axonal shearing. Clinically meaningful impairment was observed in 25% of this group; 10% had complete astereopsis. Stereoacuity screening requires 1 to 2 minutes. Undetected astereopsis may increase risk for subsequent motor vehicle accidents or falls.