| hemianopic scotoma | A scotoma involving half of the central field. (05 Mar 2000) |
|---|---|
| scintillating scotoma | A localised area of blindness edged by brilliantly coloured shimmering lights (teichopsia); usually a prodromal symptom of migraine. See: fortification spectrum. Synonym: flittering scotoma. (05 Mar 2000) |
| scotoma | 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 Origin: Gr. Skotoma (18 Nov 1997) |
| Seidel's scotoma | A form of Bjerrum's scotoma. See: Seidel's sign. (05 Mar 2000) |
| sickle scotoma | A comet-shaped scotoma, 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. Synonym: Bjerrum's sign, sickle scotoma. (05 Mar 2000) |
| negative scotoma | A scotoma that is not ordinarily perceived, but is detected only on examination of the visual field. (05 Mar 2000) |
| quadrantic scotoma | A scotoma involving a quarter segment of the central visual field. (05 Mar 2000) |
| zonular scotoma | A curved scotoma not corresponding to the path of retinal nerve fibres. (05 Mar 2000) |
| flittering scotoma | A localised area of blindness edged by brilliantly coloured shimmering lights (teichopsia); usually a prodromal symptom of migraine. See: fortification spectrum. Synonym: flittering scotoma. (05 Mar 2000) |
| blue white colour selection | <molecular biology, procedure> Method for identifying bacterial clones containing plasmids with inserts. Many modern vectors have their polycloning site within a part of the LacZ gene encoding _ galactosidase, which provides _ complementation in an appropriate mutant E. Coli strain. This means that a re ligated (empty) vector will produce blue colonies when grown on plates containing IPTG and X gal, but colonies with a substantial insert in their plasmid's polycloning site are unable to produce functional _ galactosidase and so produce white colonies. (16 Dec 1997) |
| Reuss' colour tables | An obsolete charts in which coloured letters are printed on coloured backgrounds in such combination that some of them are invisible to a person with deficient colour vision. Synonym: Stilling colour tables. (05 Mar 2000) |
| colour | 1. That aspect of the appearance of objects and light sources that may be specified as to hue, lightness (brightness), and saturation. 2. That portion of the visible (370-760 nm) electromagnetic spectrum specified as to wavelength, luminosity, and purity. Origin: L. (05 Mar 2000) |
| colour aberration | When using white light through a lens system, it is inevitable that different wave lengths (colours) are brought to a focus at slightly different points. As a consequence, there are chromatic aberations in the image, good microscope objectives are therefore corrected for this at two wave lengths (achromats) or at three wave lengths (apochromats), as well as for spherical aberration. (18 Nov 1997) |
| colour agnosia | The inability to name or identify specific colours by sight; caused by lesions of the dominant occipital and temporal lobes. (05 Mar 2000) |
| colour blindness | A sex-linked inherited condition where there is an inability to distinguish colours. Very few women are colour blind, but up to 10% of all men have some degree of colour blindness. The most common for is red-green colour blindness. The second most common is blue-yellow. Inheritance: sex-linked (X chromosome). (27 Sep 1997) |