SER in preschool children decreased significantly with increasing severity of parental myopia, study shows. Age, gender, near work time and both maternal and parental myopia were risk factors for lacking hyperopia reserve.  Photo: Getty Images. Click image to enlarge.

Myopia cases are increasing all over the world, especially in China, where it’s considered a public health threat. To understand the normal refractive development and process of myopia in order to control myopia onset as much as possible, researchers recently explored the association between parental myopia and high myopia using children’s refraction and ocular biometry.

A total of 2,053 Chinese preschool children between the ages of three and six from the Beijing Hyperopia Reserve Study were enrolled. Spherical equivalent refraction (SER), cycloplegic refraction (CR), axial length (AL) and corneal radius (CR) were measured. Parents were asked to complete a questionnaire about refractive status (no myopia; mild myopia <-3D; moderate myopia ≥-3D and ≤-6; high myopia >-6D).

There was a clear relationship between SER, AL and AL/CR ratio and the severity of parental myopia. Of the children, almost 91% had at least one myopic parent and 511 children (24.9%) had at least one highly myopic parent.

There was a progressive decrease in SER in preschool children with increasing severity of parental myopia. Compared to children without highly myopic parent(s), the children with highly myopic parent(s) had longer axial length and different patterns of age-related trend of axial elongation.

“In addition, parental myopia was also an independent risk factor for myopia in children, and a lack of hyperopia reserve and maternal myopia might play a more powerful role,” the researchers explained in their paper on the work.

These findings are comparable with a previous study that showed that the prevalence of myopia using noncycloplegic refractions in primary school was significantly associated with maternal myopia, but not with paternal myopia, in both rural and urban regions of Beijing. The authors noted, however, that a difference between paternal and maternal effects could be due to the generally greater role taken by mothers in childcare, particularly for young children.

“Additionally, our study identified that the duration of time spent on reading, writing and drawing was an independent risk factor associated with the absence of hyperopia reserves,” the authors wrote. “This suggests that even at a young age, higher educational demands may not directly lead to myopia development but could be linked to the depletion of hyperopia reserves, which could potentially contribute to myopia progression in later years.”

These results also suggested that parents with a higher degree of myopia or higher education levels encouraged their children to engage more in academic activities and less involving television and electronic devices.

Time spent on outdoor activities should be increased, the authors suggested, and any protective intervention on myopia should be started during preschool.

“In addition, even when parents are myopic, myopia prevalence is still low in preschool children, suggesting that the onset of myopia is primarily during the primary school years, and myopia prevention policies are crucial for both preschools and primary schools,” the authors noted.

“Parental myopia and near work may predispose to faster elimination of the hyperopia reserve and play a crucial role in children’s myopia before exposure to education stress,” the authors explained. “Protective intervention for myopia should be started at the preschool stage for children, especially those with severely myopic parents.”