SCOTOMA

(Lat.), n. n. Sko't-om'a3. Gen., -om'atos (-at is). Gr., o-KOTw/ua. Fr., scotome. Ger., S., Skotom. A blind patch in the field of vision. [F.] Absolute s. A s. in which all perception of light is absent. [B.] Central s. S. limited to the central part or region of the macula lutea and immediate vicinity. [F.] Color s. Color-blindne limited to a certain portion of the visual field. The vision for white light may or may not be affected. [F.] Flittering s. A flickering s. with serrated borders which spreads from the centre so as to produce a large defect"in the field. The borders of the cloud may be colored. [F.] Negative s. S. due to entire destruction of the retinal centre, and as little noticeable by the patient as the blind spot of Mariotte. [F.] Positive s. A defect in the visual field perceptible to the patient as a dark spot before his eyes. [B.] Relative s. A s. within the limits of which the perception of light is impaired, but not altogether abolished. [B.] Ring s. A ring-like s. within and outside which vision is either normal or but very slightly impaired; usually of retinal origin. [F.] Scintillating s. See Flittering s. [s. 463]