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

Background: 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.

Case Summary: 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.

Conclusion: 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.