Medical/myopia

The AFU and Urban Legend Archive
Medical
myopia

From: iayork@panix.com (Ian A. York)
Newsgroups: alt.folklore.urban
Subject: Re: health problems: wives' tales? ULs?
Date: 21 Nov 1996 11:25:21 -0500

In article <571rr1$hpg@access2.digex.net>, Donald DiPaula <dipaula@access2.digex.net> wrote: >a recent post on an SCA mailing list i'm on vectored something that i had
>often been told as a child, but now must question: the assertion that reading
>in poor conditions (poor lighting, generally) causes nearsightedness.

Myopia is partly inherited and partly environmental. Which environmental factors are most important is not entirely clear, but apparently reading in poor light conditions might be involved. As far as I know, there's no absolute answer on this.

Whitmore WG. Congenital and developmental myopia. Eye. 6 ( Pt 4):361-5, 1992.
Abstract

Both hereditary and environmental factors are important in the interactive growth of the ocular tissues responsible for determining the refractive state of the eye. Myopia has a low prevalence in otherwise healthy children and is seen with an increased prevalence early in life in many systemic and ocular diseases. Predicting how refractive error will change in any individual child after birth or at any stage of ocular development is not possible at present, although, trends can be seen in longitudinal studies. In the disease states associated with an increased prevalence of myopia, information regarding the time of onset of myopia and the specific values for the refractive components, is lacking, so that underlying mechanisms of myopia development and whether the myopia is congenital or developmental, are not known. In adults, three different types of myopia can be characterised on the basis of clinical characteristics which have prognostic significance for ocular disease. The mechanisms of ocular growth that lead to these forms of myopia are not clear. At present, treatments to prevent or slow myopic progression have been marginally beneficial and of questionable value.

Goldschmidt E.
Myopia in humans: can progression be arrested?. [Review] Ciba Foundation Symposium. 155:222-9; discussion 230-4, 1990

Abstract

The multiplicity of theories regarding the aetiology of myopia has led to numerous and partly contradictory methods of therapy. Interest has been focused on accommodation because of the established association between myopia and close work. ... Epidemiological data indicate that the maximum incidences of myopia are associated with educational systems in which the demands on the ability of the child to learn are stringent. One might introduce the term 'ocular stress' but this is clearly difficult to define and even more difficult to measure.

>activity which i engage in even more often than reading in poor light) is that
>cracking and popping the knuckles (and other joints) causes authritis. this

See <http://www.panix.com/~iayork/knuckles.html> or <http://tafkac.org/medical/knuckle_cracking.html>.

Ian "in the country of the blind, the one-eyed man is MotY" York

      Ian York   (iayork@panix.com)  <http://www.panix.com/~iayork/>
      "-but as he was a York, I am rather inclined to suppose him a
       very respectable Man." -Jane Austen, The History of England

Article 325266 of alt.folklore.urban:
Xref: world alt.folklore.urban:325266
Path: world!blanket.mitre.org!news.tufts.edu!cam-news-feed5.bbnplanet.com!news.bbnplanet.com!cam-news-hub1.bbnplanet.com!news.idt.net!feed1.news.erols.com!panix!news.panix.com!not-for-mail From: iayork@panix.com (Ian A. York)
Newsgroups: alt.folklore.urban
Subject: Re: health problems: wives' tales? ULs?
Date: 21 Nov 1996 13:33:17 -0500
Organization: Panix
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Message-ID: <57279d$mgb@panix.com>
References: <571rr1$hpg@access2.digex.net> NNTP-Posting-Host: panix.com

Here are a few more references that are a little more specific than the two I included in my previous post. Still no definite answer; the best evidence seems to be correlative.

Parssinen O. Lyyra AL.
Myopia and myopic progression among schoolchildren: a three-year follow-up study.

Investigative Ophthalmology & Visual Science. 34(9):2794-802, 1993

Abstract

PURPOSE. To discuss the factors that might explain the rate of myopic progression and the degree of myopia after a 3-year follow-up among schoolchildren with myopia. METHODS. Myopic progression among 238 schoolchildren was followed up in a randomized clinical trial of myopia treatment. The associations between the explanatory factors and myopic progression and the final value of the spherical equivalent after the follow-up were studied by analysis of variance and regression analysis. RESULTS. Myopia progressed faster among girls than boys. According to the regression models for the boys, 25% of the variation of myopic progression and 57% of the final spherical equivalent could be explained by initial spherical equivalent, age at receiving first spectacles, time spent on sports and outdoor activities, and on reading and close work. Among the girls, 30% of myopic progression could be explained by age at receiving first spectacles, time spent on reading and close work, and reading distance. Similarly, 49% of the final spherical equivalent could be explained by age at receiving first spectacles, initial spherical equivalent, time spent on reading and close work, and reading distance. The rest of the variations could not be explained by the variables measured in this study. CONCLUSIONS. The factors with the most significant relationships to myopic progression were sex, age of onset, and degree of myopia at the beginning of the follow-up. Myopic progression and final myopia were related to time spent on reading and close work and to reading distance but not, however, to accommodation stimulus.

Wong L. Coggon D. Cruddas M. Hwang CH. Education, reading, and familial tendency as risk factors for myopia in Hong Kong fishermen.

Journal of Epidemiology & Community Health. 47(1):50-3, 1993

Abstract

STUDY OBJECTIVE--The aim was to assess the influence of childhood reading on the development of myopia after allowance for familial differences in susceptibility. DESIGN--The study was a cross sectional survey. SETTING--Four fishing harbours in Hong Kong in 1989. SUBJECTS--Participants were 408 men and women aged 15-39 years old from 159 families. MAIN RESULTS--Histories of school attendance and reading habits in childhood were obtained at interview. Myopia was assessed by retinoscopy. Associations between myopia (defined as a refractive error of at least -1.0D in one or both eyes) and indices of reading in childhood were explored. Myopia was more common in subjects who had attended school (odds ratio = 1.7, 95% CI 1.0-3.0), with the highest risks in those who had started school at the earliest ages and who had spent the most time reading and writing while at primary school. Allowance for familial tendency to myopia produced no diminution in the risks associated with reading. CONCLUSIONS--These data support the hypothesis that reading in childhood is a cause of short sight.

Peckham CS. Gardiner PA. Goldstein H. Acquired myopia in 11-year-old children. British Medical Journal. 1(6060):542-5, 1977

Abstract

Children who had acquired myopia by the age of 11 years were identified from a nationally representative sample. There were no overall sex differences in its occurrence but myopia was more common in children from non-manual families than in those from manual families. Short-sighted children were more likely to come from small families and to be of higher birth order than children with normal vision, and these associations held within each social class. At 11 years myopic children showed striking advantages in educational performance over their normal-sighted peers, as judged by tests of reading, arithmetic, and general ability. After adjustments had been made for social background, this age gain still amounted to over one year. Findings obtained at 7 years of age showed that superior educational attainments were already apparent before the onset of myopia. Children with myopia read in their leisure time more often than normally sighted children, but despite the visual impairment, they participated in outdoor sports as often as other children.

      Ian York   (iayork@panix.com)  <http://www.panix.com/~iayork/>
      "-but as he was a York, I am rather inclined to suppose him a
       very respectable Man." -Jane Austen, The History of England

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