Age, sex, race, heredity, environment and nutrition have been
found to influence ametropia. In this study, the distribution of
refractive errors has been investigated in relation to age, sex,
race, education and near work, and lighting conditions. Visual
awareness and vision screening in pre-school and schoolchildren
were also investigated.
Data were collected using the Nikon auto-refractor, retinoscope,
Snellen V.A chart, and subjective techniques. 777 people were
refracted, whose ages ranged between four and eighty years.
Measurements were made in different sections of Umlazi township,
therefore people of different socio-economic sectors were
refracted.
Four year-old children were found to be hyperopic. Hyperopia
decreased and refraction shifted towards emmetropia. Myopia
started to appear at the age of ten. Myopia increased until the
age of twenty, and thereafter decreased slowly until the age of
thirty three, where the average refraction was emmetropia. From
age forty onwards, hyperopia was predominant.
The incidence of high astigmatism, high hyperopia and high myopia
is low in this community. Most people fall in the spherical
refractive error region of between -1.000 and +1.000. The curve
is leptokurtotic with highest peak around +0.250. The cylindrical
error is between -0.500 and -1.000.
No significant difference between sexes was found except at the
fourth age group (40-51), where females are more hyperopic than males. The other sex difference is at ages ten to twelve, where females develop myopia earlier than males. Illumination plays no important role in the development of refractive errors in this community. Education and near work seem to account very little to the development of myopia.
The influence of heredity on the development of ametropia was not
investigated in depth. However, there is no evidence of heredity
influencing the development of ametropia. There is a lack of vision screening and visual awareness. / Thesis (M.Optom.)-University of Durban-Westville, 1988.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/9851 |
| Date | 31 October 2013 |
| Creators | Rasengane, Tuwani A. |
| Contributors | Simpson, T. L., Turnbull, D. K. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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