| 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) |
| after-nystagmus | Nystagmus occurring after the abrupt cessation of rotation in the opposite direction of the rotatory nystagmus. (05 Mar 2000) |
| amaurotic nystagmus | The pendular or, rarely, jerky nystagmus seen in severely reduced vision. Synonym: amaurotic nystagmus. (05 Mar 2000) |
| Bruns' nystagmus | A fine, jerking (vestibular) nystagmus on horizontal gaze in one direction, together with a slower, larger amplitude (gaze, paretic) nystagmus on looking in the opposite direction; due to lateral brainstem compression, usually by a cerebellar-pontine angle mass such as an acoustic neuroma. (05 Mar 2000) |
| caloric nystagmus | Jerky nystagmus induced by labyrinthine stimulation with warm or cold water injected into the ear canal. (27 Sep 1997) |