| visual threshold | Threshold of visual sensation, the minimal light intensity evoking a visual sensation. Synonym: achromatic threshold, minimum light threshold. (05 Mar 2000) |
|---|---|
| visual violet | A visual pigment, composed of 11-cis-retinal bound to an opsin, found in the cones of the retina. Synonym: visual violet. Origin: G. Ion, violet, + ops, eye, + -in (05 Mar 2000) |
| visual yellow | The orange retinaldehyde resulting from the action of light on the rhodopsin of the retina, which converts the 11-cis-retinal component of the rhodopsin to all-trans-retinal plus opsin. Synonym: trans-retinal, visual yellow. (05 Mar 2000) |
| primary visual area | Area of the occipital lobe concerned with vision. (12 Dec 1998) |
| primary visual cortex | See: visual cortex. (05 Mar 2000) |
| secondary visual area | Area of the occipital lobe concerned with vision. (12 Dec 1998) |
| secondary visual cortex | See: visual cortex. (05 Mar 2000) |
| evoked potentials, visual | The electric response evoked in the cerebral cortex by visual stimulation or stimulation of the visual pathways. (12 Dec 1998) |
| unformed visual hallucination | Hallucination composed of sparks, lights, or bursting spheres of light. (05 Mar 2000) |
| formed visual hallucination | <psychiatry> Hallucination composed of scenes, often landscapes. (05 Mar 2000) |
| functional visual loss | An apparent loss of visual acuity or visual field with no substantiating physical signs; often due to a natural concern about visual loss combined with suggestibility and a fear of the worst; best treated with reassurance. (05 Mar 2000) |
| acid red 87 | Eosin Ys, the disodium salt of 2',4',5',7'-tetrabromofluorescein. Synonym: acid red 87, eosin yellowish. (05 Mar 2000) |
| acid red 91 | The disodium salt of 4',5'-dibromo-2',7'-dinitrofluorescein. Synonym: acid red 91, eosin I bluish. (05 Mar 2000) |
| algae, red | Algae of the division rhodophyta, in which the pigment is predominantly red; common genera are gelidium, gracilaria, and polysiphonia. (12 Dec 1998) |
| alizarin red S | Sodium alizarin sulfonate;used as a stain for calcium in bone (calcium appears red-orange, magnesium, aluminum, and barium are varying shades of red), in the determination of fluorine; as a pH indicator it changes from yellow to purple between pH 3.7 and 5.2. (05 Mar 2000) |