[Cerebral achromatopsia (symptoms, course, differential diagnosis and examination strategy). II]

To the patient, the sudden onset of cerebral achromatopsia is like switching to black and white on a color TV. As a rule, the defect arises due to bilateral ischemic infarction in the inferior occipitotemporal region. Bilateral upper homonymous quadrantanopsias usually leave the macula more or less unimpaired, so that visual acuity is largely preserved. Prosopagnosia and loss of topographic memory are often associated with central achromatopsia. Investigations of color vision must include color-naming procedures and large-field tests in addition to the conventional methods. Color-naming tasks are indispensable in differentiating cerebral achromatopsia from the aphasic and disconnective types of color anomia. The authors' recommended strategy for investigating color vision relies on records of a case of cerebral achromatopsia obtained six months and two years, respectively, after the onset of symptoms. In addition to the above-mentioned procedures, spectral increment thresholds on white and colored backgrounds were determined. For the first time in cerebral achromatopsia, examinations with large-field spectral matches were performed using the projection anomaloscope. Large-field tests are indispensable for monitoring recovery in cases of central achromatopsia. In the author's patient, recovery of blue-green discrimination was far more complete than that of red-yellow-green discrimination, and for both conditions large-field color vision was far superior to small-field.