Wilbrand's knee: does it exist?

ObjectiveIn 1904, Hermann Wilbrand reported that nasal ON fibers form a loop into the contralateral ON, subsequently referred to as Wilbrand's knee. He had further theorized that a lesion affecting Wilbrand's knee would develop a distinct visual field defect characterized by an ipsilateral central scotoma with a contralateral superotemporal visual field defect. We present clinical evidence that disputes the existence of Wilbrand's knee.MethodsA retrospective analysis of 3 patients whose ONs were divided at the ON–chiasm junction is presented. Two patients had an ONS meningioma and the other patient had sarcoidosis of the ON. Resection of the lesion and the ON up to the nerve-chiasm junction was done to prevent the disease from extending into the OC and the contralateral ON. The patients had detailed neuro-ophthalmologic evaluations preoperatively and postoperatively.ResultsAfter the resection of the ON at the ON–chiasm junction in the 3 patients, junctional scotoma could not be detected by visual perimetry.ConclusionNo clinical perimetric evidence was found to support the existence of Wilbrand's knee in the anterior visual pathway.