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Hemianopsia, or hemianopia, is a visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia (or homonymous hemianopia) is hemianopic visual field loss on the same side of both eyes. Homonymous hemianopsia occurs because the right half of the brain has visual ...
Congruous homonymous hemianopia with macular sparing is a feature of occlusion of posterior cerebral artery supplying the anterior part of the visual cortex. [1] Bilateral homonymous hemianopia with macular sparing producing a picture of ring scotoma is seen in bilateral occipital lobe lesions. [1] Pupillary reflex is normal; Optic atrophy does ...
It appears in people with damage to one hemisphere of their visual cortex, and occurs simultaneously with bilateral homonymous hemianopia or homonymous quadrantanopia. The exact mechanism behind this phenomenon is still uncertain. [1] The opposing effect, where vision in half of the center of the visual field is lost, is known as macular splitting.
Paris as seen with left homonymous hemianopsia. A homonymous hemianopsia is the loss of half of the visual field on the same side in both eyes. The visual images that we see to the right side travel from both eyes to the left side of the brain, while the visual images we see to the left side in each eye travel to the right side of the brain.
Lesions in the chiasm (e.g. Bitemporal hemianopia, loss of vision at the sides) Lesions after the chiasm (homonymous field defects like homonymous hemianopia, Quadrantanopia, homonymous scotomata) Other characterisations are: Altitudinal field defects, loss of vision above or below the horizontal meridian – associated with ocular abnormalities
Homonymous denotes a condition which affects the same portion of the visual field of each eye. [4] Homonymous inferior quadrantanopia is a loss of vision in the same lower quadrant of visual field in both eyes whereas a homonymous superior quadrantanopia is a loss of vision in the same upper quadrant of visual field in both eyes. [5]
The Sprague effect is the phenomenon where homonymous hemianopia, caused by damage to the visual cortex, gets slightly better when the contralesional superior colliculus is destroyed. [1] [2] The effect is named for its discoverer, James Sprague, who observed this phenomenon in 1966 using a cat model. [3]
Transection causes contralateral lower quadrantanopia; Lesions that involve both cunei cause a lower altitudinal hemianopia (altitudinopia) The lower division: Loops from the lateral geniculate body anteriorly (Meyer's loop), then posteriorly, to terminate in the lower bank of the calcarine sulcus, called the lingual gyrus