Electroretinographic findings in congenital oculomotor apraxia (Cogan's syndrome).

We performed visual evoked potential testing and electroretinography in five patients with Cogan's oculomotor apraxia. The visual evoked potentials were normal, confirming previously reported data. Electroretinograms were abnormal in two of the five patients examined. A previous study showed normal electroretinogram responses bilaterally in one patient. Our findings suggest the existence of two variants of the syndrome; the one with electroretinogram anomalies has a worse visual prognosis.