Vergence


Vergence

A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision.[1].

The two eyes converge to point to the same object

When a creature with binocular vision looks at an object, the eyes must rotate around a vertical axis so that the projection of the image is in the centre of the retina in both eyes. To look at an object closer by, the eyes rotate towards each other (convergence), while for an object farther away they rotate away from each other (divergence). Exaggerated convergence is called cross eyed viewing (focussing on the nose for example) . When looking into the distance, the eyes diverge until parallel, effectively fixating the same point at infinity (or very far away).

Vergence movements are closely connected to accommodation of the eye. Under normal conditions, changing the focus of the eyes to look at an object at a different distance will automatically cause vergence and accommodation.

As opposed to the 500°/s velocity of saccade movements, vergence movements are far slower, around 25°/s. The extraocular muscles may have two types of fiber each with its own nerve supply, hence a dual mechanism.[citation needed]

Vergence dysfunction

A number of vergence dysfunctions exist:[2][3]

See also

References

  1. ^ Cassin, B. Dictionary of Eye Terminology. Solomon S.. Gainesville, Fl: Triad Publishing Company. ISBN 0937404683. 
  2. ^ American Optometric Association. Optometric Clinical Practice Guideline: Care of the Patient with Accommodative and Vergence Dysfunction. 1998.
  3. ^ Duane A. "A new classification of the motor anomalies of the eyes based upon physiological principles, together with their symptoms, diagnosis and treatment." Ann Ophthalmol. Otolaryngol. 5:969.1869;6:94 and 247.1867.



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Look at other dictionaries:

  • vergence — [ vɛrʒɑ̃s ] n. f. • 1953; de convergence, divergence ♦ Phys. Inverse de la distance focale d un système optique centré. Vergence positive (⇒ convergence) , négative (⇒ divergence) . ● vergence nom féminin (de convergence) Inverse de la distance… …   Encyclopédie Universelle

  • vergence — 1902, from VERGE (Cf. verge) + ENCE (Cf. ence) …   Etymology dictionary

  • Vergence — Vergences d un faisceau. Elle est inversement proportionnelle à la distance de la focale. En optique géométrique, la vergence est une grandeur qui sert à caractériser les propriétés de focalisation d un système. C est une grandeur algébrique, qui …   Wikipédia en Français

  • vergence — A disjunctive movement of the eyes in which the fixation axes are not parallel, as in convergence or divergence. [L. vergo, to incline, to turn] v. of lens the reciprocal of the principal focal distance used as a measure of the divergence …   Medical dictionary

  • vergence — /ˈvɜdʒəns/ (say verjuhns) noun 1. Optics the inward or outward refraction of light in convergence or divergence. 2. the movement of the eyes which produces convergence (positive vergence) when the eyes turn in towards each other, or divergence… …   Australian English dictionary

  • vergence — lęšio laužiamoji geba statusas T sritis Standartizacija ir metrologija apibrėžtis Dydis, atvirkščiai proporcingas lęšio židinio nuotoliui. Matavimo vienetas – dioptrija. Žymimas dpt: 1 dpt = 1 m⁻¹. atitikmenys: angl. dioptric power; focal power;… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • vergence — /verr jeuhns/, n. Ophthalm. the turning motion of the eyeballs toward or away from each other. Cf. convergence (def. 4), divergence (def. 3). [1900 05; VERGE2 + ENCE] * * * …   Universalium

  • vergence — noun a) A measure of convergence or divergence of rays b) The simultaneous turning of both eyes when focusing …   Wiktionary

  • vergence — noun 1》 Physiology the simultaneous movement of the pupils of the eyes towards or away from one another during focusing. 2》 Geology the direction in which a fold is inclined or overturned. Origin 1980s: common element of convergence and… …   English new terms dictionary

  • vergence — ver·gence …   English syllables


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