Accommodation is achieved by changing the degree of curvature of the internal crystalline lenses of the eyes.
In youth, these are naturally elastic and become more curved when the pull on the ligament by which they are suspended is reduced by contraction of the surrounding muscle ring (CILIARY MUSCLE). The elasticity of the lenses drops progressively with age so the power of accommodation lessens.
Spectacles induce less accommodation in myopes and more accommodation in hyperopes than that exerted by an emmetrope fixating at a given distance.
Contact lenses do not induce any different accommodation than that required for a given distance.
vary, alter, change - become different in some particular way, without permanently losing one's or its former characteristics or essence; "her mood changes in accordance with the weather"; "The supermarket's selection of vegetables varies according to the season"abide by, comply, follow - act in accordance with someone's rules, commands, or wishes; "He complied with my instructions"; "You must comply or else!
"; "Follow these simple rules"; "abide by the rules" their manners and their morals to the community in which they live; and if they can occasionally obtain a degree of reverence for their supposed spiritual gifts, are, on most occasions, loaded with unmerciful ridicule, as possessing a character inconsistent with all around them.
In some animals this adjustment occurs either as a result of an anteroposterior movement of the crystalline lens, or of an alteration in the curvature of the cornea.
See aniso-accommodation; ciliary muscle; accommodative reflex; Fincham's theory; Helmholtz's of accommodation theory.amplitude of accommodation The maximum amount of accommodation A that the eye can exert.
The ability of the eye to accommodate decreases with age.
Synonym: ocular accommodation; visual accommodation See: illustration4.
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Ophthalmology The automatic adjustment of the lens curvature, resulting in a change in the focal length of the eye, which brings images of objects from various distances into focus on the retina; the ability of the eye to focus at various distances, by changing lens shape. In accommodation for near vision, the ciliary muscle contracts, causing increased rounding of the lens, the pupil contracts, and the optic axes converge.