The Impact of Parental Myopia and High Myopia on the Hyperopia Reserve of Preschool Children

INTRODUCTION

The aim of this study was to explore the association between parental myopia and high myopia with children's refraction and ocular biometry in large-scale Chinese preschool children from the Beijing Hyperopia Reserve Study.

SUBJECTS/METHODS

This cross-sectional kindergarten-based study enrolled children aged 3-6 years. Cycloplegic refraction, axial length (AL), and corneal radius (CR) were measured for all children. Parents were asked to complete a questionnaire about refractive status (no myopia, mild myopia <-3 D, moderate myopia ≥-3 D and ≤-6, and high myopia >-6 D).

RESULTS

The study enrolled 2,053 children (1,069 boys and 984 girls), with a mean age of 4.26 ± 0.96 years and mean spherical equivalent refraction (SER) of 1.11 ± 0.97 diopter. Of the children, 90.7% had at least one myopic parent, and 511 children (24.9%) had at least one highly myopic parent. SER decreased significantly with increasing severity of parental myopia (p < 0.001). Preschool children's myopia was independently associated with parental myopia (OR, 10.4 and 11.5 for one and two highly myopic parent[s]). Age (OR = 1.1), gender (OR = 1.7; girls as references), near work time (OR = 1.2), and both maternal (OR, 1.4 and 2.0 for moderate and high myopia) and paternal myopia (OR, 1.6 and 1.9 for moderate and high myopia) were independent risk factors for lacking hyperopia reserve.

CONCLUSION

Severe parental myopia was associated with a lower SER, longer AL, and higher AL/CR ratio in preschool children. Parental myopia and near work may predispose children to faster elimination of hyperopia reserves before exposure to higher educational stress.

Relationship between peripheral refraction, axial lengths and parental myopia of young adult myopes

PURPOSE

To determine the relationship between peripheral refraction at the horizontal retina, axial length and parental history of myopia between myopic adults who have positive parental myopia and those with negative parental myopia.

METHODS

69 males and 44 females in the age range of 18-25 years were assigned either a negative parental myopia (NPM) or positive parental myopia (PPM) group. In the corrected and uncorrected states, peripheral refractive error was measured up to 30° horizontally in 10° steps using an open field autorefractor. Axial length was measured using an Opto US1000 Fine A-Scan Ultrasonography (model US1000).

RESULTS

Relative peripheral refractive error showed more hyperopic defocus that was statistically significantly more increased in the positive parental myopia group than in the negative parental myopia group (P ≥ 0.02). The overall mean ± SD axial length of all subjects was 23.38 ± 0.32 mm (range 23.01-25.01 mm). The study showed a statistically significant difference (P = 0.005) in axial lengths of young adult myopes (23.45 ± 0.36 mm) with parental myopia compared to those with similar spherical equivalent refraction who have non-myopic parents (23.28 ± 0.19 mm).

CONCLUSION

There was significantly more hyperopic defocus at 30° N and 30° T retina in the corrected states of young adult myopes who had myopic parents compared to their counterparts with non-myopic parents.

Longitudinal association between myopia and parental myopia and outdoor time among students in Wenzhou: a 2.5-year longitudinal cohort study

BACKGROUND

To evaluate the impact of parental myopia and outdoor time on myopia among students in Wenzhou.

METHODS

We examined 1388 primary students from first grade to third grade in Wenzhou from September 2012 to March 2015. We performed noncycloplegic refractometry on each student every six months and axial length (AL) measurements every year. At the commencement of our study, children were asked to complete a questionnaire regarding near work activity and outdoor activity, whereas parents were asked to complete a self-administered questionnaire regarding their background circumstances and their history of myopia.

RESULTS

A total of 1294 students (93.2%) returned for follow-up examinations. Children with initial and final no myopia spent more time on outdoor activities than those with new onset myopia (1.92 vs. 1.81 h/d, p = 0.022), and elongation of AL in children with a high level (> 2.5 h/day) of outdoor time (0.22 ± 0.13 mm/Y) was less than those with a low level (≤ 1.5 h/day) of outdoor time (0.24 ± 0.14 mm/Y, p = 0.045). The proportion of rapid myopia progression (≤-0.5D/Y) was 16.7%, 20.2% and 31.5% among the children with no myopic parent, one myopic parent and two myopic parents, respectively (X² = 28.076, p < 0.001), and the elongation of AL in children among different numbers of myopic parents was significantly different (p < 0.001). A high level of outdoor time was a protective factor for children with one myopic parent (HR 0.49, 95% CI 0.27-0.88; p = 0.018).

CONCLUSIONS

In this sample, parental myopia and outdoor time were associated with myopia in children. A high level of outdoor time was a protective factor for children with one myopic parent.

Factors associated with myopia in Korean children: Korea National Health and nutrition examination survey 2016-2017 (KNHANES VII)

BACKGROUND

To evaluate the prevalence and risk factors associated with myopia and high myopia in children in South Korea.

METHODS

A total of 983 children 5-18 years of age who participated in the Korean National Health and Nutrition Examination Survey 2016-2017 (KNHANES VII), a nationwide population-based cross-sectional study, were evaluated. Myopia and high myopia were defined as a spherical equivalent (SE) ≤ - 0.5 diopters (D) and SE ≤ --6.0 D. The association between refractive errors and potential risk factors for myopia was analyzed.

RESULTS

The prevalence of myopia and high myopia was 65.4 and 6.9%, respectively. Older age and parental myopia were significantly associated with both myopia and high myopia, while higher body mass index (BMI) was associated with high myopia only. Although the proportion of subjects who spent more time on near work activities (≥4 h/day) was sequentially increased with increased refractive error, this tendency was not statistically significant by multivariable logistic regression.

CONCLUSIONS

Korean children had a high prevalence of myopia and high myopia. In this age group, the risk of myopia increased with aging and parental myopia. Higher BMI may be associated with high myopia.