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Macular sparing can be determined with visual field testing.The macula is defined as an area of approximately + 8 degrees around the center of the visual field. [3] During examination, vision in an area of greater than 3 degrees must be preserved for a patient to be considered to have macular sparing because there is involuntary eye movement within 1 to 2 degrees.
The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; [1] in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it is then considered “the field of functional capacity obtained and recorded by means of perimetry”.
The visual pathway consists of structures that carry visual information from the retina to the brain.Lesions in that pathway cause a variety of visual field defects. In the visual system of human eye, the visual information processed by retinal photoreceptor cells travel in the following way:
Peripheral vision is usually spared since the pattern of loss typically involves a central or cecocentral scotoma, a visual field defect at or surrounding the point of fixation. This pattern can be revealed via visual field testing. Upon examination, the pupils usually demonstrate a normal response to light and near stimulation. In those who ...
Hemianopsia, or hemianopia, is a visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia (or homonymous hemianopia) is hemianopic visual field loss on the same side of both eyes. Homonymous hemianopsia occurs because the right half of the brain has visual ...
The visual field defects can vary, and while some patients may experience immediate maximal vision loss, others may notice a gradual worsening. The optic disc in these cases can appear swollen, sometimes accompanied by hemorrhages. [ 41 ]
Visual acuity often remains stable and poor (around or below 20/200) with a residual central visual field defect. Patients with the 14484/ND6 mutation are most likely to have visual recovery. [8] Dominant optic atrophy is an autosomal dominant disease caused by a defect in the nuclear gene OPA1. A slowly progressive optic neuropathy, dominant ...
Aneurysms of the anterior communicating artery are the most common circle of Willis aneurysm [4] and can cause visual field defects such as bitemporal heteronymous hemianopsia (due to compression of the optic chiasm), [5] psychopathology and frontal lobe pathology. [6]