Impact of Heredity in Myopia

Abstract

A series of 109 like-sexed twin pairs in the age group 30–31 years (54 monozygotic and 55 dizygotic) with one or both members of the twins with myopia was found in the Finnish Twin Cohort. The series was based on a random sample of 1,200 twins in one age stratum of the cohort. The twins received a questionnaire on their health status with special reference to eye diseases and symptoms. The refractive status of the twin pairs was ascertained by asking the twins to send their latest prescription for glasses to the authors or the refraction was obtained from the ophthalmologists or opticians of the twins. The mean difference in refraction between the monozygotic twins was 1.19 dptr in the right eyes and 1.15 dptr in the left eyes. The difference between dizygotic pairs was 2.34 dptr in the right eyes and 2.47 dptr in the left eyes. Analysis of variance showed that the difference in refraction between the two eyes of a twin pair was not significant. The mean difference in refraction between the monozygotic twins was significantly lower than that between dizygotic twins (p ≤ 0.001). The intrapair variances were doubled among dizygotic twin pairs compared to monozygotic twin pairs in the male group. The intrapair variance in the female group was 4-fold among dizygotic twin pairs as compared to monozygotic twin pairs. Heritability of myopia was 0.58 (0.74 for males and 0.61 for females) when myopia was considered a dichotomous variable. This result suggests that inheritance has a substantial effect on the etiology of myopia.

Near work, education, family history, and myopia in Greek conscripts

“…The influence of genetic factors on the development of myopia has been supported by twin studies. 4,15,16 The only other study on myopia carried out in Greece also supported the association of parental family history with myopia. 10 However, Saw et al 17 showed that, although parental myopia was significantly related to offspring myopia, the relationship became nonsignificant when adjusted for educational level and other environmental factors.…”

Prevalence of myopia in a sample of Greek students

“…Proof for heritability of myopia is a study of monozygotic and dizygotic twin pairs in Finland (Teikari et al 1991). A greater percentage of concordant pairs (both twins myopes or both emmetropes) among monozygotic twin pairs was found compared to dizygotic twin pairs.…”

“…A total number of 1852 questionnaires were distributed to students in order to collect data on their refractive condition. We consider the questionnaire method to be of sufficient validity, taking into account that certain other studies were based on this method (Teikari et al 1991;Zadnik et al 1994).…”

“…Several studies have shown that the prevalence of myopia increases with the level of education (Sperduto et al 1983;Teasdale et al 1988). It has also been supported that myopia is partly hereditary (Teikari et al 1991;Zadnik et al 1994). This study's aim is to examine the major epidemiological characteristics of myopia in the Greek student population and to identify the specific factors that cause myopia incidence.…”

“…A total number of 1852 questionnaires were distributed to students in order to collect data on their refractive condition. We consider the questionnaire method to be of sufficient validity, taking into account that certain other studies were based on this method (Teikari et al 1991;Zadnik et al 1994).Students were asked to quote their refractive situation using their ophthalmologist's prescription. They were also asked to determine their parents' and siblings' refractive situation, their performance at school, the hours they studied daily, the potential use of glasses or contact lenses and their habits.…”