scotoma

1. An isolated area of varying size and shape, within the visual field, in which vision is absent or depressed. 2. A blind spot in psychological awareness. [G. skotoma, vertigo, fr. skotos, darkness]

- absolute s. a s. in which there is no perception of light.

- anular s. a circular s. surrounding the center of the field of vision. See ring s..

- arcuate s. a s. extending from the blind spot and arching into the nasal field following the lines of retinal nerve fibers.

- Bjerrum s. a comet-shaped s., occurring in glaucoma, attached at the temporal end to the blind spot or separated from it by a narrow gap; the defect widens as it extends above and nasally curves around the fixation spot, and then extends downward to end exactly at the nasal horizontal meridian. SYN: Bjerrum sign, sickle s..

- cecocentral s. a s. involving the optic disk area (blind spot) and the papillomacular fibers; there are three forms: 1) the cecocentral defect, which extends from the blind spot toward or into the fixation area; 2) angioscotoma; 3) glaucomatous nerve-fiber bundle s., due to involvement of nerve-fiber bundles at the edge of the optic disk. SEE ALSO: Bjerrum s., Røonne nasal step.

- central s. a s. involving the fixation point.

- color s. an area of depressed color vision in the visual field.

- flittering s. SYN: scintillating s..

- glaucomatous nerve-fiber bundle s. cecocentral s..

- hemianopic s. a s. involving half of the central field.

- mental s. absence of insight into, or inability to comprehend, items relative to a subject whose content is highly emotional to the individual. SYN: blind spot (2).

- negative s. a s. that is not ordinarily perceived, but is detected only on examination of the visual field.

- paracentral s. a s. adjacent to the fixation point.

- pericentral s. a s. that surrounds the fixation point more or less symmetrically.

- peripheral s. a s. outside of the central 30 degrees of the visual field.

- physiologic s. the negative s. in the visual field, corresponding to the optic disk. SYN: blind spot (1).

- positive s. a s. that is perceived as a black spot within the field of vision.

- quadrantic s. a s. involving a quarter segment of the central visual field.

- relative s. a s. in which there is visual depression but not complete loss of light perception.

- ring s. an annular area of blindness in the visual field surrounding the fixation point in pigmentary degeneration of the retina and in glaucoma.

- scintillating s. a localized area of blindness edged by brilliantly colored shimmering lights (teichopsia); usually a prodromal symptom of migraine. SEE ALSO: fortification spectrum. SYN: flittering s..

- Seidel s. a form of Bjerrum s.. SEE ALSO: Seidel sign.

- sickle s. SYN: Bjerrum s..

- zonular s. a curved s. not corresponding to the path of retinal nerve fibers.

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sco·to·ma skə-'tō-mə n, pl -mas or -ma·ta -mət-ə a spot in the visual field in which vision is absent or deficient

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n. (pl. scotomata)

a small area of abnormally less sensitive or absent vision in the visual field, surrounded by normal sight. All people have a blind spot in the visual field of each eye due to the small area inside the eye occupied by the optic disc, which is not sensitive to light. Similar islands of total visual loss in other parts of the field are referred to as absolute scotomata. A relative scotoma is a spot where the vision is decreased but still present.

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sco·to·ma (sko-toґmə) pl. scotoґmata [Gr. skotōma] 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 s.