Vision, Visual Acuity, and Ocular Refraction of Young Men

Purpose: We undertook this study with the aim to determine static ametropias of black Cameroonians as well as their clinical manifestations. It is a prospective study carried out in the Department of Ophthalmology of Douala General Hospital from January 1996 to December 1998. Patients and Method: During this period, all patients who fulfilled our criteria had a skiascopy done under cycloplegia. We thus examined 2,484 patients (4,968 eyes). 66.2% of them were female and 33.8% were male. Results: In our series, hyperopia was found in 51% of the cases, hyperopic astigmatism in 27.5% of the cases, myopic astigmatism in 9.3% of cases, mixed astigmatism in 7.7% of cases and myopia in 4.5% of cases. Distribution of ametropias is influenced by age, not by sex or laterality. Discussion and Conclusion: Functional signs just have an indicative value; only objective refraction under cycloplegia can determine exactly the ametropia.

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“…Des études réalisées au sein de populations leucodermes ont relevé des taux de myopie allant de 12,03 à 28% [1,8].…”

Section: Discussionunclassified

Les amétropies statiques du noir camerounais

Mvogo

Bella-Hiag²,

Ellong³

et al. 2001

Ophthalmologica

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“…In some populations, such as Australia 26 and the South Pacific island of Vanuatu, 27 emmetropisation appears to continue and the population becomes even more leptokurtotic with a low incidence of myopia and hyperopia. In most populations that have been studied to date, an opposite pattern is observed with an increasing level of myopia leading to increased variance, reduced leptokurtosis, and a negative skew, as opposed to the positive skew observed in Figure 1 A representation of the refractive data from Sorsby et al 4 and a prediction for the distribution of human refraction based on an uncorrelated combination of ocular components as measured by Steiger. 5 younger cohorts.…”

Section: Development Of Refraction Up To Agementioning

confidence: 99%

“…3 This is demonstrated in Figure 1, which shows data from Sorsby's 1953 study of young male army recruits. 4 Compared with a Gaussian distribution of the same mean and standard deviation, the refractive data show a great excess of subjects clustered close to the mean and also a greater degree of variation at the extremes. In adult human refraction data there is also an excess of myopes, especially high myopes, which is the source of the negative skew.…”

Section: Introductionmentioning

confidence: 99%

Emmetropisation and the aetiology of refractive errors

Flitcroft

2014

Eye

140

124

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The distribution of human refractive errors displays features that are not commonly seen in other biological variables. Compared with the more typical Gaussian distribution, adult refraction within a population typically has a negative skew and increased kurtosis (ie is leptokurtotic). This distribution arises from two apparently conflicting tendencies, first, the existence of a mechanism to control eye growth during infancy so as to bring refraction towards emmetropia/low hyperopia (ie emmetropisation) and second, the tendency of many human populations to develop myopia during later childhood and into adulthood. The distribution of refraction therefore changes significantly with age. Analysis of the processes involved in shaping refractive development allows for the creation of a life course model of refractive development. Monte Carlo simulations based on such a model can recreate the variation of refractive distributions seen from birth to adulthood and the impact of increasing myopia prevalence on refractive error distributions in Asia.

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“…At birth, all humans are born hypermetropic and the ocular changes between birth and puberty follow a leptokurtotic distribution that overwhelmingly favors emmetropia and is skewed towards myopia [4,5]. It appears that emmetropization can be accounted for in part by coordinated growth of the eye and in part by some form of vision dependent feedback system for ocular refractive development.…”

Section: Genesis Of Refractive Error In Children: Theory Of Emmetropimentioning

confidence: 99%