Visual purple Health Dictionary

Visual Purple: From 1 Different Sources


Visual Acuity

See VISION.... visual acuity

Visual Field

The total area in which visual perception is possible while a person is looking straight ahead.

The visual fields normally extend outwards over an angle of about 90 degrees on either side of the midline of the face, but are more restricted above and below, especially if the eyes are deep-set or the eyebrows are prominent.

The visual fields of the 2 eyes overlap to a large extent, giving binocular vision.

Partial loss of the visual field may occur in glaucoma or stroke.... visual field

Purple Loose-strife

Lythrum salicaria. N.O. Lythraceae.

Synonym: Purple Grass, Willow Strife.

Habitat: By waterways; luxuriantly on river islands and banks.

Features ? Stem four- (sometimes six-) sided, up to four feet high. Leaves in pairs, threes or fours, nearly sessile, lanceolate, margins entire, two to five inches long. Flowers (July to September) large, reddish-purple, six to eight in rings round the stalk. Root woody.

Part used ? Herb.

Action: Febrifuge, astringent, alterative.

Chiefly in feverish conditions with other herbs. Sometimes as an astringent in diarrhea. Used alone, simmer 1 ounce in 1 1/2 pints water for ten minutes. Dose, wineglassful as required.... purple loose-strife

Visual Evoked Response

Stimulation of the retina of the EYE with light causes changes in the electrical activity of the cerebral cortex (see BRAIN). These changes can be measured from outside the skull and can give valuable information about the state of the visual pathway from the retinal ganglion cells to the occipital cortex. Not only can it determine that function is normal, it can also help to diagnose some causes of poor VISION.... visual evoked response

Acuity, Visual

See visual acuity.... acuity, visual

Visual Pathway

see optic nerve.... visual pathway

Visual Reinforcement Audiometry

(visual reinforced audiometry, VRA) a behavioural test of hearing for children aged approximately 6 to 30 months in which the subject sits between two calibrated loudspeakers. A sound is generated from one loudspeaker. Children who turn towards the sound are rewarded by brief illumination of a toy adjacent to the loudspeaker. Older children can be tested with headphones, rather than using the loudspeakers, to enable each ear to be tested separately. The test can be adapted for use with older subjects who have learning disabilities.... visual reinforcement audiometry



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