Amplitude of accommodation
- Amplitude of accommodation
Amplitude of accommodation (AA) is a measurement of the eye’s ability to focus clearly on objects at near distances (i.e. accommodation). This eye focusing range for a child is usually about 5–7.5 cm (2–3 inches). For a young adult, it is 10–15 cm (4–6 inches). The focus range for a 45-year-old adult is about 50 cm (20 inches). For an 80-year-old adult, it is 1.5 m (60 inches). [http://www.vision-therapy.com/Glossary_of_Terms.htm]
The average amplitude of accommodation, in diopters, for a patient of a given age may be estimated by Hofstetter's formula: 18.5 minus one third of the patient's age in years. [Scheiman, Mitchell and Wick, Bruce. "Clinical Management of Binocular Vision." Lippincott, New York. 1994.]
ee also
*Convergence insufficiency
*Eye examination
*Negative relative accommodation
*Positive relative accommodation
*Presbyopia
References
External links
*http://www.ijo.in/article.asp?issn=0301-4738;year=2005;volume=53;issue=2;spage=105;epage=108;aulast=Abraham
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Look at other dictionaries:
amplitude of accommodation — n the difference between the refracting power of the eye when adjusted for vision at the far point and when adjusted for vision at the near point * * * range of accommodation; see under range … Medical dictionary
amplitude of accommodation — the difference between the refracting power of the eye when adjusted for vision at the far point and when adjusted for vision at the near point … Useful english dictionary
Accommodation (eye) — Accommodation is the process by which the increases optical power to maintain a clear image (focus) on an object as it draws near the eye. The young human eye can change focus from distance to 7 cm from the eye in 350 milliseconds. This dramatic… … Wikipedia
accommodation — [ akɔmɔdasjɔ̃ ] n. f. • XIVe « prêt gratuit » (cf. accommodement); de accommoder 1 ♦ (1566) Action d accommoder ou de s accommoder (aux circonstances, aux individus). ⇒ adaptation. 2 ♦ Physiol. Aptitude de l œil à accommoder (III). L amplitude d… … Encyclopédie Universelle
amplitude — [ ɑ̃plityd ] n. f. • XVe; lat. amplitudo 1 ♦ Vx Grandeur, étendue. « Dans l amplitude et immensité de la nature » (Pascal). 2 ♦ Sc. Différence entre les valeurs extrêmes d une grandeur. Amplitude d un intervalle borné : distance entre les bornes … Encyclopédie Universelle
Accommodation — In medicine, the ability of the eye to change its focus from distant to near objects (and vice versa). This process is achieved by the lens changing its shape. Accommodation is the adjustment of the optics of the eye to keep an object in focus on … Medical dictionary
Negative relative accommodation — (NRA) was proposed by Prof. Joseph Kearney of Oxford University in 1967, is a measure of the maximum ability to relax accommodation while maintaining clear, single binocular vision.[1] This measurement is typically obtained by an orthoptist,… … Wikipedia
Positive relative accommodation — (PRA) is a measure of the maximum ability to stimulate accommodation while maintaining clear, single binocular vision [http://www.vision therapy.com/Glossary of Terms.htm] . This measurement is typically obtained by an ophthalmologist or… … Wikipedia
Spasm of accommodation — A spasm of accommodation (also known as an accommodation, or accommodative, spasm) is a condition in which the ciliary muscle of the eye remains in a constant state of contraction. Normally, this contraction bends the lens to allow the eye to… … Wikipedia
range of accommodation — n the range through which accommodation is able to adjust the optical system of the eye so that an image falls in sharp focus on the retina: the distance between the near point and the far point of the eye * * * the alteration in the refractive… … Medical dictionary
