Bitemporal hemianopsia is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field.

[1][2] In bitemporal hemianopsia, vision is missing in the outer (temporal or lateral) half of both the right and left visual fields.

When there is compression at the optic chiasm, the visual impulse from both nasal retina are affected, leading to inability to see the temporal, or peripheral, field of vision.

Knowing the neurocircuitry of visual signal flow through the optic tract is very important in understanding bitemporal hemianopsia.

A cause of vascular origin is an aneurysm of the anterior communicating artery which arises superior to the chiasm, enlarges, and compresses it from above.