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Why can a tumor near the pituitary gland affect vision?
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Endocrine system
The glands of the human endocrine system.
A tumor near the pituitary gland can affect vision because of the gland's close proximity to the optic chiasm, the area where the optic nerves from both eyes cross.1
As a tumor grows in this region, it can compress these nerve fibers. Specifically, the fibers that cross at the chiasmāwhich are responsible for transmitting visual information from the outer parts of the visual fieldsāare often the most affected. This compression can lead to atrophy of the nerve fibers and result in vision loss, such as bitemporal hemianopia, where the outer portions of a person's visual field become abnormal.21