"The Wilbrand knee refers to a small anterior loop of axons from the medial retina passing a short distance into the contralateral prechiasmatic optic nerve after decussating in the optic chiasm. It is said to account for the occurrence of the junctional scotoma caused by lesions at the junction of the optic nerve and chiasm; characterised by ipsilateral central scotoma with additional superior temporal visual field defect in the contralateral eye."
"The existence of the Wilbrand knee is, however, controversial and some research suggests that it is an artifact resulting from long-term enucleation 1,3."