| facial vision | <physiology> Sensing the proximity of objects by the nerves of the face, presumed in the case of the blind and also in sighted persons who are blindfolded or in darkness. (05 Mar 2000) |
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| yellow vision | <ophthalmology> A form of chromatopsia in which objects looked at appear yellow. Origin: Gr. Opsis = vision (11 May 1997) |
| Young-Helmholtz theory of colour vision | A theory that there are three colour-perceiving elements in the retina: red, green, and blue. Perception of other colours arises from the combined stimulation of these elements; deficiency or absence of any one of these elements results in inability to perceive that colour and a misperception of any other colour of which it forms a part. Synonym: Helmholtz theory of colour vision. (05 Mar 2000) |
| line of vision | The straight line extending from the object seen, through the centre of the pupil, to the macula lutea of the retina. Synonym: line of vision. (05 Mar 2000) |