Familial aggregation for myopia and contributions of environmental and genetic factors

Abstract EN

Background : The etiology of myopia, the most common refractive error, is known to involve a host of genetic and environmental causes but the precise contribution of these factors and their interactions are yet to be defined.

The objective of this project is to examine familial relationships for myopia among siblings of myopic patients and the distributions of hereditary and environmental factors on it. Methods : In this study, 401(81.1%) siblings out of 490 invited sibling were participated from 162 families.

The participants aged 16 years and above, had myopia of at least 0.5 diopters in one or both eyes.

We performed visual examinations and interviews for data on the manifest refraction, age, sex, ethnic, height, education and the amount of near works.

Odds Ratios (OR) were used as a measure of familial aggregation and logistic regression with approach of second order Generalized Estimating Equations (GEE) was fitted to control possible of confounding factors. Results : Of the participants, 315 (78.6%) were myopic.

There is strong evidence for a familial aggregation, as the odds ratio for myopia among family members was 4.13 (95% CI=2.47-6.89, P < 0.001).

Among other variables, only sex and education showed a significant association with myopia; after adjustment for these factors, the familial -aggregation persisted with OR = 2.18 (95% CI = 1.67-2.84, P < 0.001).

Conclusion : There is an obvious familial aggregation for myopia, but the association is somewhat attenuated by adjusting for education and sex, and these confounding variables may in turn act through genetic or environmental mechanisms.

We conclude that both heredity and environment are at work in myopia and further studies are needed to confirm and quantify their respective effects.