annular scotoma


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Related to annular scotoma: negative scotoma

scotoma

 [sko-to´mah] (Gr.)
1. an area of lost or depressed vision within the visual field, surrounded by an area of less depressed or of normal vision.
2. mental scotoma. adj., adj scotom´atous.
absolute scotoma an area within the visual field in which perception of light is entirely lost.
annular scotoma a circular area of depressed vision surrounding the point of fixation.
arcuate scotoma an arc-shaped defect of vision arising in an area near the blind spot and extending toward it.
central scotoma an area of depressed vision corresponding with the fixation point and interfering with or abolishing central vision.
centrocecal scotoma a horizontal oval defect in the visual field situated between and embracing both the fixation point and the blind spot.
color scotoma an isolated area of depressed or defective vision for color in the visual field.
hemianopic scotoma depressed or lost vision affecting half of the central visual field; see also hemianopia.
mental scotoma in psychiatry, a figurative blind spot in a person's psychological awareness, the patient being unable to gain insight into and to understand his mental problems; lack of insight.
negative scotoma a scotoma appearing as a blank spot in the visual field; the patient is unaware of it, and it is detected only by examination.
peripheral scotoma an area of depressed vision toward the periphery of the visual field.
physiologic scotoma that area of the visual field corresponding with the optic disk, in which the photosensitive receptors are absent.
positive scotoma one which appears as a dark spot in the visual field.
relative scotoma an area of the visual field in which perception of light is only diminished, or loss is restricted to light of certain wavelengths.
ring scotoma annular s.
scintillating scotoma blurring of vision with the sensation of a luminous appearance before the eyes, with a zigzag, wall-like outline; called also teichopsia.

annular scotoma

A scotomatous zone that encircles the point of fixation like a ring, not always completely closed but leaving the fixation point intact. Synonym: ring scotoma
See also: scotoma