Ishihara color plates utilized as an assessment for simultanagnosia in posterior cortical atrophy: A case report

Simultanagnosia is a neurological disorder that impairs an individual's ability to perceive more than one object at a time visually. While the individual may acknowledge the presence of multiple objects in his field of view, he cannot generally summarize the overall percept.

We describe a case of simultanagnosia in Posterior Cortical Atrophy, evidenced by the Ishihara color test. A 54-year-old woman complained of reading problems despite normal visual acuity and a structural eye exam. The patient failed to identify any of the Ishihara color plates in either eye despite adequate naming of colors. Automated visual field testing showed a homonymous hemianopia. Structural and functional neuroimaging and cerebrospinal fluid analysis were consistent with posterior cortical atrophy.

Simultanagnosia can be tested with the Ishihara pseudoisochromatic plates because the recognition of embedded number patterns in the test requires appreciation of a collection of individual stimuli.