NBCE Exam 2026 – 400 Free Practice Questions to Pass the National Board of Chiropractic Examiners

Bitemporal hemianopia is associated with an optic chiasm lesion due to the specific arrangement of the optical fibers. In the optic chiasm, the fibers from the nasal (inner) halves of each retina cross over to the opposite side, while the fibers from the temporal (outer) halves remain on the same side. A lesion at the optic chiasm affects the crossing fibers from the nasal retinas, leading to a loss of vision in the temporal field of both eyes. This results in bitemporal hemianopia, where the individual can still see centrally but has a loss of vision on the outer half of both visual fields.

The other types of visual field defects describe different patterns of vision loss that do not occur specifically with optic chiasm lesions. Homonymous hemianopia typically results from lesions in the optic tract or occipital lobe, affecting the same side of each visual field (e.g., right side of both eyes or left side of both eyes). Quadrantanopia involves a loss of vision in a quarter of the visual field, often due to localized lesions that impact specific areas of the visual cortex. Scotoma refers to an area of partial or complete vision loss surrounded by a field of normal vision,