Hemianopia in more detail

Hemianopia, also called hemianopsia
Partial or complete loss of vision in one half of the visual field(s) of one or both eyes. Diminished vision or full vision loss in the left or right half of the visual field of one or both eyes.

Types of hemianopia- each named depending on the region of the visual field that is affected

1. Homonymous hemianopsia

Refers to a visual defect that affects both eyes equally and occurs either to the left or right of the midline of the visual field. It is a visual field defect involving either the two right or the two left halves of the visual fields of both eyes.This is the most common pattern of vision loss.

2. Bitemporal hemianopia – bilateral loss of vision in the temporal fields

3. Altitudinal hemianopia– characterized by a visual defect above or below the horizontal meridian of the visual field.

Superior hemianopia: Superior hemianopia is when loss of vision occurs in the upper visual field of either the left or right eye or both.

Inferior hemianopia: Inferior hemianopia is when loss of vision occurs in the lower visual field of either the left, right, or both eyes.

 
4. Binasal hemianopia– loss of vision in the nasal hemifields of both eyes.

5. Quadrantanopia– loss of vision in one quarter of the visual field in one or both eyes.

Clinically:

• Lesion of right optic tract will cause visual field defect on the left side, i.e. left homonymous hemianopia.
• Parietal lobe lesion will cause inferior homonymous quadrantanopia.
• Temporal lobe lesion will cause superior homonymous quadrantanopia.

Symptoms of homonymous hemianopsia

• Bumping into or failing to notice things on the side of the hemianopsia. This can make such everyday tasks as crossing the street or driving a car unsafe.
• Missing parts of words or parts of an eye chart on the side of the hemianopsia when reading.
• Not noticing objects on a desk or table, or even food on a plate to the side of the hemianopsia.
• Frustration with reading because it is difficult for the eyes to pick up the beginning of the next line.
• Tendency to turn the head or body away from the side of the hemianopsia.
• Drifting in a direction away from the hemianopsia when walking.
• Visual hallucinations that appear in the form of lights, shapes, or geometric figures or as the image of a recognizable object. Sometimes a movement noted on the normal side of vision is believed to be also seen at the same time on the side of the visual loss.

Resources
https://interestingmedical.com/visual-field-defects/2/
https://www.sightscience.com/what-is-hemianopia/
https://my.clevelandclinic.org/health/diseases/15766-homonymous-hemianopsia-