Parents not totally responsible for child’s eyesight
MedWire News: Research from Guangzhou, China shows that a high proportion of children with myopia do not have highly myopic parents, indicating that environmental as well as genetic factors contribute to the development of the eye condition.
Indeed, half of the children in the study with high myopia (spherical equivalent >6 D) had parents with no myopia, reports the research team in Optometry and Vision Science.
However, the study also found that more severe parental myopia carries an increased risk for myopia developing in children, with a 1.5-fold increased risk for developing the condition by the age of 12-15 years if children had one parent who reported high myopia.
"One explanation of the impact of parental myopia is that myopic parents create myopigenic environments for their children, with an emphasis on near work," say Mingguang He (Zhongshan Ophthalmic Center) and colleagues.
However, the team adds that despite this, "it is clear that environmental factors in Guangzhou affect a significant proportion of highly myopic children."
The study included 1504 children with one parent who had no myopia, and one parent with either no (n=1114), mild (n=241), moderate (n=117), or high (n=32) myopia.
In all, 57.7% of children were myopic, including 74.3% of 15-year-olds, which provided a better estimate of myopia in adults, remark He and co-authors. By contrast, 83.6% of parents had no myopia and, of the 16.4% who did, just 1.4% reported high myopia.
While He et al admit that parental myopia was self-reported by questionnaire, a substudy of 98 parent participants underwent noncycloplegic refraction and the agreement between self-reported and objective refractive status was "substantial," they say.
Having one highly myopic parent increased the risk for myopia in the children by a significant 1.53 times compared with having no myopic parents, while children with one parent highly myopic were 11.1-fold more likely to develop high myopia than children without myopic parents.
Conversely, for 86.8% of highly myopic children, neither parent was highly myopic, and for 45.3% of them, neither parent had any myopia.
Myopia is one of the priority targets of the World Health Organization Vision 2020 Program, since it leads to both correctable and uncorrectable visual impairment, explain the researchers.
By Sarah Guy