scotoma, pi. scoto'mat a

(sko-to'mah) [G. skotoma, darkne .] spot of varying size and shape, within the visual field, in which there is no vision, ann'ular s., ring s., a circular blank area surrounding the center of the field of vision, cen'tral s., absence of vision at the point of fixation on the retina, color s., a patch of color-blindne in the visual field. flitter'ing s., scintillating s. in's ular s., a. small spot of blindne surrounded by an area of good vision, neg'ative s., one.which is not ordinarily perceived, but is detected only on examination of the entire visual field, paracen'- tral s., one which is only partly central, the fixation point not being entirely obscured, perIph'eral s., a spot where vision' is absent anywhere within the field of vision outside of the point of fixation, physio log'ical s., blind-spot, the point on the retina where the optic nerve enters, pos'itive s., one which is perceived subjectively as a black spot within the field of vision, rel'ative s., one in which vision is impaired but not entirely destroyed, ring s., annular s. scin'till at ing s., fortification-spectrum, teichopsia; the appearance of a dark patch with bright zigzag outline in the visual field of one or both eyes; it is usually of short duration and is indicative of eyestrain or follows intense mental or physical labor.