A scotoma is a localized area of impaired vision within an otherwise normal visual field. Mapping of the defect may be manual, by confrontation testing, or automated. In addition to the peripheral field, the central field should also be tested, with the target object moved around the fixation point. A central scotoma may be picked up in this way, or a more complex defect, such as a centrocecal scotoma in which both the macula and the blind spot are involved. Infarction of the occipital pole will produce a central visual loss, as will optic nerve inflammation. Scotomata may be absolute (no perception of form or light) or relative (preservation of form, loss of color).
A scotoma may be physiological, as in the blind spot or angioscotoma, or pathological, reflecting disease anywhere along the visual pathway from retina and choroid to visual cortex.
Various types of scotoma may be detected (see individual entries for more details):
Cecocentral or centrocecal scotoma Arcuate scotoma
Annular or ring scotoma Junctional scotoma
Junctional scotoma of Traquair Peripapillary scotoma (enlarged blind spot)
Altitudinal field defect; Angioscotoma; Blind spot; Central scotoma, Centrocecal Scotoma; Hemianopia; Junctional scotoma, Junctional scotoma of traquair; Maculopathy; Papilledema; Quadrantanopia; Retinitis pigmentosa; Retinopathy; Visual field defects