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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 ...
Homonymous hemianopia on the contralateral side may occur when posterior chiasmal lesions involve the optic tract. [1] Lateral chiasmal lesions may produce binasal hemianopia. [1] Lesions at the junction of the optic nerve and chiasm may produce an ipsilateral monocular temporal scotoma known as 'junctional scotoma'.
2. Bitemporal hemianopia 3. Homonymous hemianopia 4. Quadrantanopia 5. & 6. Quadrantanopia with macular sparing. The visual pathway consists of structures that carry visual information from the retina to the brain. Lesions in the pathway cause a variety of visual field defects. The type of field defect can help localize where the lesion is ...
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.
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 ]
Lesions in the optic tract correspond to visual field loss on the left or right half of the vertical midline, also known as homonymous hemianopsia. A lesion in the left optic tract will cause right-sided homonymous hemianopsia, while a lesion in the right optic tract will cause left-sided homonymous hemianopsia.
If a lesion only exists in one unilateral division of the optic radiation, the consequence is called quadrantanopia, which implies that only the respective superior or inferior quadrant of the visual field is affected. If both divisions on one side of the brain are affected, the result is a contralateral homonymous hemianopsia.
Visual pathway lesions From top to bottom: 1. Complete loss of vision, right eye 2. Bitemporal hemianopia 3. Homonymous hemianopsia 4. Quadrantanopia 5&6. Quadrantanopia with macular sparing. Proper function of the visual system is required for sensing, processing, and understanding the surrounding environment.