The Amplitude of Accommodation in Presbyopia

Hamasaki, D.I.; Ong, Jin; Marg, Elwin

doi:10.1097/00006324-195601000-00002

Cited by 157 publications

(81 citation statements)

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“…When we compared this subjective accommodative amplitude and the results of the objective measurements shown in Figs. 6 and 7, the results of subjective measurements were larger than those with binocular, natural viewing by an average of 2.9 D, and were also larger than those with monocular, internal target gazing by an average of 3.6 D. These figures were larger than the differences between subjective and objective measurements which had been obtained in the past (Hamasaki 1956;Sun et al 1988;Koretz et al 1989;Nishida 1990). …”

Section: Discussionmentioning

confidence: 80%

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An Experimental Study on the Objective Measurement of Accommodative Amplitude under Binocular and Natural Viewing Conditions.

Otake

Miyao

Ishihara

et al. 1993

Tohoku J. Exp. Med.

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Section: Discussionmentioning

confidence: 80%

“…In stigmatoscopy using a normal light source (Ames and Gliddon 1928; Bannon et al 1950;Hamasaki et al 1956), the ray of light incident to the retina acts as accommodative stimulation and may affect the measurement. The development of optometers which use infrared light, however, has resolved these problems.…”

mentioning

confidence: 99%

An Experimental Study on the Objective Measurement of Accommodative Amplitude under Binocular and Natural Viewing Conditions.

Otake

Miyao

Ishihara

et al. 1993

Tohoku J. Exp. Med.

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“…68 R. F. FISHER It must be remembered that the in vivo values were obtained by measuring the point at which blurring of an object is first noticed by the observer. From the experiments of Hamasaki, Org & Marg (1956) and Miles (1953) it would appear that this method of measurement gives a higher value than the true amplitude of accommodation. Text- fig.…”

Section: Accommodation/force Curvementioning

confidence: 96%

“…Presbyopic changes in maximum amplitude of accommodation (a comparison of in vivo and in vitro data). *, Duane (1922); @, Bruckner (1959) (mean per decade); Q, Hamasaki et al (1956); 0, Donders (1864 The relation between amplitude of accommodation and the force of contraction of the ciliary muscle…”

Section: Accommodation/force Curvementioning

confidence: 99%

The force of contraction of the human ciliary muscle during accommodation

Fisher¹

1977

The Journal of Physiology

210

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SUMMARY1. Apparatus has been designed to alter the shape of the human lens by tensile forces applied to the zonular fibres indirectly through the ciliary body. The changes in dioptric power of the lens for monochromatic sodium light were measured at the same time. Simultaneous serial photography, and direct measurement enabled one to relate a change in shape of the lens to the change in dioptric power. Subsequently, the same lens was isolated and spun around its antero-posterior polar axis and high speed photography recorded its changing profile.2. By comparing the changes in lens profile due to zonular tension and centrifugal force respectively, the force developed in the zonule for a given change in the shape of the lens could be calculated. Changes in dioptric power associated with those of shape can thus be related directly to the force of contraction of the ciliary muscle necessary to reduce the initial tension of the zonule in the unaccommodated state.3. The force of contraction of the ciliary muscle as measured by radial force exerted through the zonule and the change in dioptric power of the lens were not linearly related. The relationship is more exactly expressed by the equationwhere D = amplitude of accommodation in dioptres (m-l), FCB = force of contraction of the ciliary muscle as measured by changes in tension of the zonule (N), Kdf = dioptric force coefficient and is constant for a given age (m'-N-A x 102.5). This coefficient is 0-41 at 15 yr and 0-07 at 45 yr of age.4. In youth for maximum accommodation (10-12 D) the force is approximately 10 x 10-2 N while to produce sufficient accommodation for near vision (3-5 D) the force is less than 0-05 x 10-2 N.5. After the age of 30 yr the force of contraction of the ciliary muscle necessary to produce maximum accommodation rises steadily to about 50 yr of age and thereafter probably falls slightly. At about 50 yr of age the ciliary muscle is some 50 % more powerful than in youth.6. Even if hypertrophy of the muscle did not occur the amplitude of accommodation would be reduced at the most by only 0-8 D of that observed at the onset of presbyopia.

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“…Conversely, for distant objects the response exceeds the stimulus vergence and this error is often termed the accommodative 'lead'. Previous research has demonstrated that the accommodative response is dependent on subject and target characteristics such as pupil size [2,3], age [4] luminance [5] and spatial frequency [6,7]. In the absence of adequate visual stimuli accommodation adopts an intermediate resting position [8,9].…”

Section: Introductionmentioning

confidence: 99%

The accommodative response, refractive error and mental effort: 1. The sympathetic nervous system

Bullimore

Gilmartin

1988

Doc Ophthalmol

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The accommodative response of 12 emmetropic subjects was measured for an array of numbers located at -1, -3 and -5 dioptres using an objective infra-red optometer. Responses were compared for passive (reading numbers) and active (adding numbers) conditions. The imposition of mental effort induced a significant increase in mean response for the -1 D stimulus, a response equivalent to the passive condition at -3 D and a reduction in response at -5 D. Mental effort induced similar responses for the -1 D and -3 D locations when sympathetic innervation to the ciliary muscle was blocked with the beta-receptor antagonist timolol maleate. Responses for the -5 D location were, however, significantly increased. It is proposed that sympathetic inhibition can modify the effect of mental effort on near accommodative responses.

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The Amplitude of Accommodation in Presbyopia

Cited by 157 publications

References 0 publications

An Experimental Study on the Objective Measurement of Accommodative Amplitude under Binocular and Natural Viewing Conditions.

An Experimental Study on the Objective Measurement of Accommodative Amplitude under Binocular and Natural Viewing Conditions.

The force of contraction of the human ciliary muscle during accommodation

The accommodative response, refractive error and mental effort: 1. The sympathetic nervous system

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