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Lesions involving the whole optic nerve cause complete blindness on the affected side, that means damage at the right optic nerve causes complete loss of vision in the right eye. [3] Optic neuritis involving external fibers of the optic nerve causes tunnel vision. [4] Optic neuritis involving internal fibers of the optic nerve causes central ...
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. Stroke, congenital defects, tumors, infection, and surgery are all possible causes of optic tract damage.
Vascular and neoplastic (malignant or benign tumours) lesions from the optic tract, to visual cortex can cause a contralateral homonymous hemianopsia. Injury to the right side of the brain will affect the left visual fields of each eye. The more posterior the cerebral lesion, the more symmetric (congruous) the homonymous hemianopsia will be.
Therefore, damage to the right side of the posterior portion of the brain or right optic tract can cause a loss of the left field of view in both eyes. Likewise, damage to the left posterior brain or left optic radiation can cause a loss of the right field of vision. [3] Paris as seen with binasal hemianopsia
Bitemporal hemianopsia is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary gland. [1] [2]
Posterior lesions may also involve the optic tract and cause a contralateral homonymous hemianopia. Optic disc pallor may be apparent with an ophthalmoscope if the result is longstanding. If the lesion does not affect the lateral uncrossed fibers, the pallor may take on a bow-tie configuration.
Binasal hemianopsia is the medical description of a type of partial blindness where vision is missing in the inner half of both the right and left visual field. It is associated with certain lesions of the eye and of the central nervous system, such as congenital hydrocephalus.
A lesion affecting one side of the temporal lobe may cause damage to the inferior optic radiations (known as the temporal pathway or Meyer's loop) which can lead to superior quadrantanopia on the contralateral side of both eyes (colloquially referred to as "pie in the sky"); if the superior optic radiations (parietal pathway) are lesioned, the ...