Scotoma

{sko-tof -mah) [cKoroq, darkne ]. An area in the visual field, rays of light from which are not at all (Absolute S.) or imperfectly (Relative S.) perceived. S., Central, one limited to the region of the visual field corresponding to the macula lutea. S., Color-, color-blindne limited to a part of the visual field, and which may exist without interruption of the field for white light. S., Flittering, a S. with serrated margins extending peripherally and producing a large defect in the visual field. It is also called fortification-spectrum. S., Negative, a defect due to the destruction of the retinal center, and which is not noticeable to the patient. S., Positive, a S. perceptible to the patient as a dark spot before his eyes. S., Relative, a scotoma within which perception of light is only partially impaired. S., Ring-, S., Annular, a zone of scotoma surrounding the center of the visual field. S. scintillans, S., Scintillating. See S., Flittering. 571