Wilbrand's knee: does it exist?

In 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.

A 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.

After the resection of the ON at the ON-chiasm junction in the 3 patients, junctional scotoma could not be detected by visual perimetry.

No clinical perimetric evidence was found to support the existence of Wilbrand's knee in the anterior visual pathway.