Accommodative-Convergence in Presbyopia

Morgan, Meredith W.; Peters, Henry B.

doi:10.1097/00006324-195101000-00003

Cited by 29 publications

(11 citation statements)

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“…AC/A ratio. As mentioned above, there has been considerable disagreement concerning age-related changes in the AC/A ratio, this being found to increase slightly (Davis and Jobe, 1957;Bruce et al, 1995), decrease slightly (Alpern and Larson, 1960) or remain relatively constant (Morgan and Peters, 1951;Ogle et al, 1967;Ciuffreda et al, 1997), although all these findings correspond to the adult population. Gwiazda et al (1999), in a population aged 5-21 years, found the response AC/A ratios to be negatively correlated with age, but only for the myopes.…”

Section: First Groupmentioning

confidence: 98%

“…The stimulus AC/A ratio determines the change in accommodative convergence that occurs when the patient accommodates or relaxes accommodation by a given amount, and is an important parameter for differential diagnosis in anomalies of binocular vision (Scheiman and Wick, 2002). In contrast to the universal agreement on the age-related reduction in accommodative amplitude (Hofstetter, 1944;Chen et al, 2000;Jime´nez et al, 2003), considerable disagreement surrounds age-related changes in the AC/A ratio throughout life: increasing (Davis and Jobe, 1957), decreasing (Alpern and Larson, 1960) or remaining constant (Morgan and Peters, 1951;Ogle et al, 1967;Ciuffreda et al, 1997;Mutti et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…, 2000; Jiménez et al. , 2003), considerable disagreement surrounds age‐related changes in the AC/A ratio throughout life: increasing (Davis and Jobe, 1957), decreasing (Alpern and Larson, 1960) or remaining constant (Morgan and Peters, 1951; Ogle et al. , 1967; Ciuffreda et al.…”

Section: Introductionmentioning

confidence: 99%

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Statistical normal values of visual parameters that characterize binocular function in children

Jiménez

Perez

García

et al. 2004

Ophthalmic Physiologic Optic

102

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A wide range of visual parameters used to evaluate binocular function were evaluated in a paediatric population (1056 subjects aged 6-12 years). Mean values are provided for these ages in optometric tests that directly assess the vergence system, horizontal phorias for near and far vision (measured by a modified version of the Thorington method), negative and positive vergence amplitude for near and far vision (step vergence testing), vergence facility (flippers 8 Delta BI/8 Delta BO), and near-point of convergence (penlight push-up technique and red-lens push-up technique), as well as stimulus accommodative convergence/accommodation ratio and stereoacuity (Randot test) which provide an overall evaluation of the vergence, accommodative and oculomotor systems. A statistical comparison (anova and Bonferroni post hoc test) of these values between ages was performed. The differences, although statistically significant, were not clinically meaningful, and therefore we identified two trends in the behaviour of these parameters. For all parameters, except for vergence facility, we established a single mean reference value for the age range studied. The difference between the means for vergence facility indicated the need to divide the population into two age ranges (6-8 and 8-12 years). This study establishes statistical normal values for these parameters in a paediatric population and their means are a valuable instrument for separating children with binocular anomalies from those with normal binocular vision.

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Section: First Groupmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Statistical normal values of visual parameters that characterize binocular function in children

Jiménez

Perez

García

et al. 2004

Ophthalmic Physiologic Optic

102

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“…One metre-angle is the convergence required to fixate an object at 1 m; an angle y in metre-angles can be converted to prism dioptres using the equation z=y.PD, where PD is the inter-pupillary distance in centimetres and z is the angle in prism dioptres. Other studies, however, have shown the AC/A ratio to remain stable or even decrease with age [1,7,23,34]. The majority of these studies were cross-sectional in nature and the age range of their subjects was relatively wide.…”

Section: Introductionmentioning

confidence: 99%

The effect of incipient presbyopia on the correspondence between accommodation and vergence

Baker

Gilmartin

2002

Graefe's Arch Clin Exp Ophthalmol

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The results of this study fail to support the Hess-Gullstrand theory of presbyopia in that the ciliary muscle effort required to produce a unit change in accommodation increases, rather than stays constant, with age. Data show that the near vision response is limited to the maximum vergence response that can be tolerated and, despite being within the amplitude of accommodation, a stimulus may still appear blurred because the vergence component determines the proportion of available accommodation utilised during near vision.

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“…8,18,19 This fact was explained by a mild weakening of the extraocular muscle function. Changes in extraocular muscles and disturbance in muscle fiber alignment have been detected after age 30.…”

Section: Discussionmentioning

confidence: 99%