page_title: Visual field
section_title: Field defects in visual pathway lesions
hierarchical_section_title: Visual field / Visual field loss / Field defects in visual pathway lesions
caption_attribution_description: English: Visual field defects in visual pathway lesion
context_page_description: The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point.
  The equivalent concept for optical instruments and image sensors is the field of view.
  In optometry, ophthalmology, and neurology, a visual field test is used to determine whether the visual field is affected by diseases that cause local scotoma or a more extensive loss of vision or a reduction in sensitivity.
context_section_description: 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 located (see figure).
  A lesions in the optic nerve of one eye causes partial or complete loss of vision in the same eye, with an intact field of vision in other eye.
  A lesion at the proximal part of optic nerve of one eye cause, central field defect in one eye  and temporal half-field defect in the other eye (not shown in the figure).
  A lesion in the center of the optic chiasma causes bitemporal hemianopia 
  A lesion to the optic tract, or involving the complete optic radiation causes homonimous hemianopia
  When part of the optic radiation in the parietal lobe is affected, the resulting field defect may be inferior quadrant hemianopia
caption: Visual pathway lesions 
   From top to bottom: 
   1. Complete loss of vision in the right eye 
   2. Bitemporal hemianopia 
   3. Homonymous hemianopia 
   4. Quadrantanopia 
   5.& 6. Quadrantanopia with macular sparing
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