A new visual defect, shadow, or curtain across part of your vision.
From the orlandosentinel.com
If strokes or injuries cause damage to the area of the brain that processes the information of the visual sense, this results in a visual field defect.
From the sciencedaily.com
The technique can not only show limitations in visual fields, but can trace the defect to individual retinal photoreceptor cells.
From the sciencedaily.com
Contrast between a defect and the bulk of the sample may be enhanced for visual examination by the unaided eye by using liquids to penetrate fatigue cracks.