A heterogenous group of visual problems that can result in blind areas of the visual field. Visual field defects can result from damage anywhere along the visual pathway including lesions at the retina, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiations and at the visual cortex. Examples of visual field defects include: homonymous hemianopsia, heteronymous hemianopsia (such as binasal hemianopsia, bitemporal hemianopsia), homonymous quadrantanopsia.