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Related to chiasma syndrome: Wilbrand's knee
a syndrome characterized by a bitemporal visual field defect and optic nerve atrophy due to a lesion in or about the chiasm.
pl. chiasmata [L., Gr.] chiasm; in genetics, the points at which members of a chromosome pair are in contact during the prophase of meiosis and because of which recombination, or crossing over, occurs on separation.
the process by which a chiasma is formed; it is the cytological basis of genetic recombination, or crossing over.
optic atrophy with bilateral hemianopia.