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The amplitude of accommodation is the maximum potential increase in optical power that an eye can achieve in adjusting its focus. It refers to a certain range of object distances for which the retinal image is as sharply focussed as possible. Amplitude of accommodation is measured during routine eye-examination. The closest that a normal eye can focus is typically about 10 cm for a child or young adult. Accommodation then decreases gradually with age, effectively finishing just after age fifty.〔Anderson H, Hentz G, Glasser A, Stuebing K, Manny R. Minus-Lens–Stimulated Accommodative Amplitude Decreases Sigmoidally with Age: A Study of Objectively Measured Accommodative Amplitudes from Age 3. Invest Ophthalmol Vis Sci 2008; 49; 2919-2926.〕〔Atchison D, Capper E, McCabe, K. Critical subjective measurement of amplitude of accommodation. Optom Vis Sci 1994; 71: 699-706〕〔Hamasaki D, Ong J, Marg E. The amplitude of accommodation in presbyopia. Am J Optom 1956; 33: 3-14.〕 The average amplitude of accommodation, in diopters, for a patient of a given age was estimated by Hofstetter in 1950 to be 18.5 - (0.30 * patient age in years) with the minimum amplitude of accommodation as 15 - (0.25 * age in years), and the maximum as 25 - (0.40 * age in years). However, Hofstetter's work was based on data from two early surveys〔Duane A. Studies in monocular and binocular accommodation with their clinical applications. Trans Am Ophthalmol Soc 1922; 20: 132-157〕〔Donders F. On the anomalies of the accommodation and refraction of the eye. (W. Moore Trans.) UK: The New Sydenham Society, 1864. p 207-209.〕 which, although widely cited, used methodology with considerable inherent error. ==See also== *Convergence insufficiency *Eye examination *Negative relative accommodation *Positive relative accommodation *Presbyopia 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Amplitude of accommodation」の詳細全文を読む スポンサード リンク
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