what is a chiasm in vision
The optic chiasm or optic chiasma is an X-shaped space, located in the forebrain, directly in front of the hypothalamus.Crucial to vision, the left and right optic nerves intersect at the chiasm, thus creating the hallmark X-shape.One-half of each nerve's axons (their long, threadlike portions) enters the opposite tract at this location, making it a partial decussation (crossing).hile rare, optic gliomas â tumors â can grow within the chiasm or in conjunction with hypothalamic tumors. Gliomas can directly affect the optic nerves. Benign (noncancerous) and typically occurring before age 20, symptoms of optic glioma can include: 1  Bulging eyes or vision loss.