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A lesion involving complete optic chiasm, which disrupts the axons from the nasal field of both eyes, causes loss of vision of the right half of the right visual field and the left half of the left visual field. [3]
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.
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.
Examples of segment 1 pathologies include left optic neuritis (inflammation or infection of the left optic nerve), detachment of left retina, and an isolated small stroke involving only the left pretectal nucleus. Therefore, options (a), (d), (e), (f), and (g) are possible. A combined lesion in segments 3 and 5 as cause of defect is very unlikely.
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.
The left optic nerve and the optic tracts. A Marcus Gunn pupil indicates an afferent defect, usually at the level of the retina or optic nerve. Moving a bright light from the unaffected eye to the affected eye would cause both eyes to dilate, because the ability to perceive the bright light is diminished. Specialty: Ophthalmology, Optometry
This condition, caused by a sudden loss of blood flow to the optic nerve, can result in severe and permanent vision loss. In the second Danish study, ...
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 ...