A study of ocular refraction in western Newfoundland

Richler, Avrum (1979) A study of ocular refraction in western Newfoundland. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Myopia is a debilitating condition that, in extreme cases, can cause blindness. For over 100 years, investigators have argued its etiology, with the hereditary and environmental schools polarized to the extreme. It was felt that a study of a population which had been exposed to two types of near work environments and which was fairly stable in composition would further elucidate the relative influences of these factors on refraction. -- The population of three communities in Western Newfoundland was studied. These communities had been relatively isolated until about 1956, and had not had formal compulsory education until 1948. Subjects were examined optometrically and psychologically to investigate previously reported associations of ocular refraction with near work, personality and body build. Familial resemblances for refraction and near work were also examined. -- The study took place as part of a larger health survey undertaken by the Faculty of Medicine at Memorial University of Newfoundland. Nine hundred and seventy-one subjects, or 80% of the target population were examined. -- This study addressed directly refraction, near work, education, heredity, personality and body build, to investigate previously reported associations of these variables. A literature review is presented for each of these reported associations, followed by results of the investigation. -- The findings were that females were more myopic than males and achieved myopia earlier than the males in this population. Those under 30 years of age had more negative mean refraction than those over 30. Those who started school in 1948 were 30 years of age at the time of the study (1974). Those who did substantial near work at work or at leisure had more negative refractions. Near work showed substantial correlation with refraction after adjustment for other influencing variables, at all ages. The parallel fit of mean near work, in hours, to mean refraction by five year age intervals over essentially the entire life span was striking. -- The number of persons in this population with uncorrected refractive errors was very high compared to the United States population. This represents a serious public health problem. -- It was found that the correlation of first degree relatives for refraction was on the order of .20 to .25, and could have been inflated by familial similarities in near work patterns. -- Contrary to previous claims, no association was found for refraction and personality or body build.

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