What causes homonymous lower quadrantanopia?

What causes homonymous lower quadrantanopia?

Homonymous superior quadrantanopia is caused by damage to the contralateral inferior parts of the posterior visual pathway: the inferior optic radiation (temporal Meyer loop), or the inferior part of the occipital visual cortex below the calcarine fissure.

What causes unilateral quadrantanopia?

Conclusion : Unilateral quadrantanopia appears to have been caused by pituitary tumor with intratumor hemorrhage, or pituitary apoplexy, that compressed the posterior portion of optic chiasm upwards.

What is homonymous quadrantanopia?

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.

What causes macular sparing?

Macular sparing may be caused by collateral vascular supply to the macular region or by the very large macular representation in the occipital cortex; additionally, bilateral representation of macular vision has been suspected.

What causes left homonymous hemianopia?

What causes homonymous hemianopsia? The most common cause of this type of vision loss is stroke. However, any disorder that affects the brain — including tumors, inflammation and injuries — can be a cause.

What is homonymous hemianopia?

Homonymous hemianopia is a visual field defect involving either the two right or the two left halves of the visual fields of both eyes.

How does hemianopia occur?

3 Homonymous hemianopia is a loss of the right or left halves of the visual field of both eyes (Figure 1a, 1b) and usually occurs as a result of a middle cerebral or posterior cerebral artery stroke affecting either the optic radiation or visual cortex of the occipital lobe (Figure 2).

Which is the best description of homonymous quadrantanopsia?

Discussion. The usual clinical interpretation of homonymous quadrantanopsia is the effect of lesions of the optic radiations course between the optic tract and the striate cortex. Superior homonymous defects are generally associated with temporal lobe lesions, whereas inferior defects commonly result from lesions of the parietal lobe.

What are the different types of quadrantanopia defects?

The defect is usually bilateral as it is typically caused by a lesion past the optic chiasma. It may be homonymous (binasal, bitemporal, upper or lower), crossed (one upper and the other lower), congruous (equal size of the defects) or incongruous (unequal size of the defects). Syn. quadrantanopsia; quadrantic anopsia; quadrantic hemianopia.

What does quadrantanopia stand for in medical terms?

quadrantanopia, inferior. An inferior homonymous loss of vision in two quarters due to a lesion of the superior fibres of the optic radiations in the parietal lobe on the contralateral side of the visual pathway. Syn. ‘pie on the floor’ defect.

What’s the difference between inferior and superior quadrantanopia?

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 3).