# deviation

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Related to deviation: standard deviation, Average deviation

## deviation

[de″ve-a´shun]**1.**a turning away from the regular standard or course.

**2.**in ophthalmology, strabismus.

**3.**in statistics, the difference between a sample value and the mean.

**axis deviation**an axis shift in the frontal plane, as seen on an electrocardiogram. There are three types:

*Left,*from −30° to −90°;

*Right,*from +90° to +180°; and

*Undetermined,*which may be either extreme left or extreme right, from −90° to +180°.

**conjugate deviation**dysfunction of the ocular muscles causing the two eyes to diverge to the same side when at rest.

**sexual deviation**sexual behavior or fantasy outside that which is morally, biologically, or legally sanctioned, often specifically one of the paraphilias.

**standard deviation**(SD) the dispersion of a random variable; a measure of the amount by which each value deviates from the mean. It is equal to the square root of the variance. For data that have a normal distribution, about 68 per cent of the data points fall within (plus or minus) one standard deviation from the mean and about 95 per cent fall within (plus or minus) two standard deviations. Symbol σ.

**ulnar deviation**a hand deformity, seen in chronic rheumatoid arthritis and lupus erythematosus, in which swelling of the metacarpophalangeal joints causes the fingers to become displaced to the ulnar side. Called also ulnar drift. See illustration.

## de·vi·a·tion

(dē'vē-ā'shŭn),**1.**A turning away or aside from the normal point or course.

**2.**An abnormality.

**3.**In psychiatry and the behavioral sciences, a departure from an accepted norm, role, or rule. Synonym(s): deviance

**4.**A statistical measure representing the difference between an individual value in a set of values and the mean value in that set.

[L.

*devio,*to turn from the straight path, fr.*de,*from, +*via,*way]## deviation

/de·vi·a·tion/ (de″ve-a´shun)**1.**variation from the regular standard or course.

**2.**strabismus.

**3.**the difference between a sample value and the mean.

**complement deviation**inhibition of complement fixation or complement-mediated immune hemolysis in the presence of excess antibody.

**conjugate deviation**deflection of the eyes in the same direction at the same time.

**immune deviation**modification of the immune response to an antigen by previous inoculation of the same antigen.

**radial deviation**

**1.**a hand deformity sometimes seen in rheumatoid arthritis, in which the fingers are displaced to the radial side.

**2.**splinting of arthritic hands into this position to correct ulnar deviation.

**sexual deviation**sexual behavior or fantasy outside that which is morally, biologically, or legally sanctioned, often specifically one of the paraphilias.

**standard deviation**(SD) a measure of the amount by which each value deviates from the mean; equal to the square root of the variance; symbol σ.

**ulnar deviation**a hand deformity of chronic rheumatoid arthritis and lupus erythematosus in which swelling of the metacarpophalangeal joints causes displacement of the fingers to the ulnar side.

## deviation, axis

[dē′vē·ā′shən]

Etymology: L,

*deviare,*to turn aside,*axle*(in electrocardiography) an abnormal direction of the mean electrical current of the heart.

## deviation

Vox populi A departure from a norm. See Septal deviation, Standard deviation.## de·vi·a·tion

(dē'vē-ā'shŭn)**1.**A turning away or aside from the normal point or course.

**2.**An abnormality.

**3.**psychiatry, behavioral sciences A departure from an accepted norm, role, or rule.

Synonym(s): deviance.

**4.**statistics A measurement representing the difference between an individual value in a set of values and the mean value in that set.

[L.

*devio,*to turn from the straight path, fr.*de,*from, +*via,*way]## deviation

See SEXUAL DEVIATION## deviation

**1.**In strabismus, the departure of the visual axis of one eye from the point of fixation.

**2.**A change in direction of a light ray resulting from reflection or refraction at an optical surface.

*angle of d.**See*angle of deviation.

**conjugate deviation**The simultaneous and equal rotations of the eyes in any direction. It may be physiological such as versions, or pathological, due to either muscular spasm or paralysis.

*See*disjunctive movements; version.

**dissociated vertical deviation**

**(DVD)**A form of strabismus in which one eye apparently moves vertically without any compensatory movement from the other eye. Although initially felt to disobey Hering's law, it is now felt that Hering's law is observed if the horizontal, vertical and rotational aspects of the condition are considered together. This form of strabismus often accompanies infantile esotropia and is almost always noted from the period of infancy. The misalignment can be either latent or manifest, and may require operative intervention if of a great degree.

*See*

**Faden procedure**;

**Bielschowsky's phenomenon test**.

**Hering-Hillebrand deviation**The deviation of the apparent frontoparallel plane horopter from the Vieth-Müller circle (horopter) (Fig. D2).

**minimum deviation of a prism**

*See*

**minimum deviation of a prism**.

**primary deviation**The deviation found in paralysis of an extraocular muscle when the unaffected eye is fixating.

**secondary deviation**The deviation found in paralysis of an extraocular muscle when the eye with the paralytic muscle is fixating.

**skew deviation**A form of strabismus, typically vertical, that does not follow any standard or typical pattern and is usually difficult to quantify. It may be due to a midbrain disorder, multiple sclerosis or myasthenia gravis.

**vertical deviation**

**1.**Type of ocular deviation found in strabismus in which the deviating eye is rotated upward with respect to the fixating eye.

**2.**Upward ocular deviation of an occluded eye in the cover test, as found in hyperphoria or hypophoria.

## de·vi·a·tion

(dē'vē-ā'shŭn)**1.**A turning away or aside from the normal point or course.

**2.**An abnormality.

[L.

*devio,*to turn from the straight path, fr.*de,*from, +*via,*way]## deviation

variation from the regular standard or course.

1. In ophthalmology, a tendency for the visual axes of the eye to fall out of alignment owing to muscular imbalance.

2. in statistics the difference between the predicted value of a variable and the actual value.

**standard deviation**

a measure of statistical dispersion. See

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