Monocular central dazzle after thalamic infarcts

The authors observed a patient after he had ischemic strokes in both parame dian thalamic regions, which were more marked on the left side. Symptoms in cluded dysphasia, vertical binocular diplopia, right-sided hemianopia, and a right-sided sensory and motor deficit, sparing the face. However, the mos t disturbing phenomenon was a painless, left monocular dazzle, which was th e presenting symptom and also the only persisting symptom. This report show s that a thalamic lesion may be at the origin of central dazzle, and to the authors' knowledge, it is the first clinical observation of its monocular occurrence. It is conceivable that this dazzle was due to optic-trigeminal summation.