Survey of ophthalmic conditions in a Labrador community. I. Refractive errors.

Abstract

SUMMARY Of the 745 available members of the population of Nain in Labrador 650 (87%) were screened for refractive errors and ocular disease. Refraction by retinoscopy was done in 553 and axial length measured by an optical method in 514. The results showed that the incidence of low degrees of myopia was higher in Inuit (Eskimos) and those of Mixed Inuit-Caucasian blood in the age groups 10 to 40 than in those over 40. 75% of the myopes came from 20 families in which myopia was present in 2 or more generations. Although there was no significant correlation between the refraction of parents and offspring, there were significant correlations between them for axial length. The axial lengths of the myopic eyes of the Inuit and Mixed populations were significantly longer than emmetropic and hypermetropic eyes. The younger members of the population were taller than their parents, and except in female Caucasians axial length showed a significant positive correlation with height. More myopes than emmetropes and hypermetropes achieved grade 8 or more in school. It is suggested that the increased incidence of myopia in the younger age groups might be due to environmental factors interfering with the process of emmetropisation in eyes with a genetic predisposition to myopia by virtue of inheriting a slightly longer eye. Better nutrition resulting in an increase in stature may also have had some influence.There are now a number of reports of an increased incidence of myopia in the younger generations of North American Indians and Inuit (Eskimos) in Canada and Alaska (Young et al., 1969;Cass, 1973;Boniuk, 1973;Morgan and Munro, 1973;Woodruff and Samek, 1977). Surveys of such populations have shown few cases of myopia in the older population but incidences of 30 to 80% have been found in the 15 to 35 age groups, suggesting that environmental rather than genetic factors are concerned.Data from routine eye clinics in Nain, Labrador, suggested that there was such an excess of myopia in this population, but as this apparent excess in the younger population might have been due to sampling errors it was decided to attempt a total population survey of refractive errors and other eye conditions in Nain during a regular 6-monthly eye clinic. The resident population of Nain, which lies at latitude 28 Inuit were away seal hunting and were not available for examination.Under the auspices of the International Grenfell Association and with the help and support of the Canadian National Institute for the Blind a team of ophthalmologists and a refracting optician visited Nain for 2 weeks in October 1977. The examinations were held in the Nursing Station, and in addition to the collection of data for the survey any necessary ophthalmic treatment was also provided. Patients and methodsThose willing to attend for examination were given appointments, usually on a family basis, and a data sheet was made out for each person. The name, age, sex, height, and weight were completed by the nurse, and the people were then seen by one of the ophthalmologis...

Body Stature Growth Trajectories during Childhood and the Development of Myopia

“…By comparing growth trajectories in children with the stature of their parents, Botton et al 40 have shown that this relatively straightforward scenario hides a complex interplay of maternal and paternal genetic, epigenetic or shared environment effects, alternating in their impact at different stages of childhood. Our findings regarding the growth trajectories of height (and weight) and ocular component dimensions at age 15, were in accordance with the consensus from previous work [13][14][15][16][17][18][19]25 , namely, that tall individuals tend to have larger eyes (a longer axial length and a flatter cornea). Again, however, the magnitude of these associations in the ALSPAC cohort was modest -explaining at most a few percent of the natural variation in AXL and RCC at age 15 years.…”

“…Indeed, studies in newborns, children and adults have demonstrated associations between body stature and axial eye length, providing indirect evidence for co-ordinated growth of the eye and body (after adjusting for the typically observed difference in axial length between the sexes) [11][12][13][14][15][16][17][18][19][20][21] . Direct support for a causal association comes from studies of individuals who fail to produce insulin-like growth factor 1 (IGF-1) due to growth hormone (GH) deficiency.…”

Can we prevent angle-closure glaucoma?

“…11 Similar prevalences were documented in Labrador 12 and in Alaska. 13 The surveys in Table 1 are arranged geographically from west to east.…”

Prevalence of strabismus among students in Natal/RN - Brazil

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