Ishihara color plates as a test for simultanagnosia.
OBJECTIVE
To alert ophthalmologists to the use of Ishihara color plates in the detection of simultanagnosia.


METHODS
We examined seven patients referred for impaired vision. Evaluation included color plate testing with Ishihara color plates.


RESULTS
All seven patients had simultanagnosia, with marked difficulty in identifying the numbers in Ishihara color plates despite adequate visual acuity and the ability to name all of the colors in the plates correctly. One of these patients was referred with the diagnosis of a cone dystrophy because of her poor performance on the Ishihara test. All of the patients had bilateral occipitoparietal damage or atrophy on magnetic resonance imaging.


CONCLUSIONS
Ophthalmologists must be aware that a poor performance with Ishihara plates may not be attributable to an impairment of color vision but rather to occipitoparietal brain damage associated with simultanagnosia.
Brazis
P W
PW
Department of Neurology, Mayo Clinic Jacksonville, Florida 32224, USA.
Graff-Radford
N R
NR
Newman
N J
NJ
Lee
A G
AG
D000377:Agnosia / Q000175:diagnosis*; D001927:Brain Diseases / Q000175:diagnosis*; D003118:Color Perception; D003119:Color Perception Tests / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009778:Occipital Lobe / Q000473:pathology*; D010296:Parietal Lobe / Q000473:pathology*