Final answer:
The optic nerve creates a blind spot on the visual field where there are no photoreceptors. However, bilateral hemianopia, which involves the loss of peripheral vision, is usually caused by a pituitary gland growth pressing on the optic chiasm, not by the typical blind spot related to the optic nerve.
Step-by-step explanation:
The optic nerve has no sensory receptors, which creates a blind spot on the visual field. At the point where the optic nerve exits the retina, there are no rods or cones to detect light, hence the term 'blind spot'. Our brains typically fill in the gap in our visual field, so we do not notice the blind spot in everyday activities. Moreover, because our two eyes have overlapping fields of vision, one eye can usually see what the other cannot due to its blind spot.
In cases like bilateral hemianopia, it is not the blind spot that causes vision issues, but a different type of damage. When a pituitary gland growth presses against the optic chiasm, it can affect the transmission of visual signals from the periphery, leading to the loss of lateral peripheral vision. This condition is different from a blind spot because visual information from the superior and inferior fields remains intact.