Does myopia occur earlier in children if their parents are myopic?

Paper title: Association of Parental Myopia With Higher Risk of Myopia Among Multiethnic Children Before School Age

Authors: Xuejuan Jiang (1,2), Kristina Tarcy-Hornoch (3,4), Susan A. Cotter (5), Saiko Matsumura (6), Paul Mitchell (7), Kathryn A. Rose (8), Joanne Katz (9), Seang-Mei Saw (6,10), Rohit Varma (11)

1. USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of South California, Los Angeles
2. Department of Preventative Medicine, Keck School of Medicine, University of Southern California, Los Angeles
3. Department of Ophthalmology, University of Washington, Seattle
4. Department of Ophthalmology, Seattle Children's Hospital, Seattle, Washington
5. Southern California College of Optometry, Marshall B. Ketchum University, Fullerton
6. Singapore Eye Research Institute, Singapore
7. Centre for Vision Research, Westmead Institute, Sydney, Australia
8. Discipline of Orthoptics, Graduate School of Health, University of Technology Sydney, Ultimo, Australia
9. Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
10. Saw Swee Hock School of Public Health, National University of Singapore, Singapore
11. Southern California Eye Institute, CHA Hollywood Presbyterian Medical Centre, Los Angeles

Date: 2020

Reference: Jiang X, Tarczy-Hornoch K, Cotter SA, Matsumura S, Mitchell P, Rose KA, Katz J, Saw SM, Varma R; POPEYE Consortium. Association of Parental Myopia With Higher Risk of Myopia Among Multiethnic Children Before School Age. JAMA Ophthalmol. 2020 May 1;138(5):501-509. [Link to open access paper]

This cohort study combined refractive and demographic data from 9793 pre-school children across 3 population-based studies to explore an association between parental myopia and myopia development in children, particularly if parental myopia was early-onset.

Myopia in parents was defined as using spectacles or contact lenses for distance use.  The myopic prevalence rate in children for having either a myopic father or mother was found to be similar (13.3% and 12.5% respectively).

The age at which both parents became myopic was found to be significant, where myopic prevalence and myopic refractive error were increased for all of the children over 12 months old.  Children with parents who first used distance spectacles when 11 years of age or younger had a myopia prevalence of 12.8% (from mother) or 13.4% (from father).  When the myopia onset-age for the parents increased to between 12 and 20 years of age, the prevalence reduced to 10.9% for mothers and 12.1% for fathers.  If the onset age was 21 years or older for both mother and father, the prevalence rate reduced further to approximately 8%. 

For children who had myopic parents, the effect of parental myopia was found to be dose-dependent where the odds ratio for early onset myopia in the child were found to be 1.42 for one myopic parent, 2.70 for both myopic parents and 3.39 if both parents had experienced early onset myopia.

Myopia in parents was seen to be associated with an increased risk of myopia in pre-school children, a greater prevalence of myopia, a higher ratio of axial length to corneal curvature radius and a more myopic (or less hyperopic) refractive error, even for non-myopic children.  This was found to be the case regardless of the race/ethnicity of the children featured in the studies.

Parental myopia, especially childhood-onset, may provide a predisposition for young children developing myopia before starting school.

When assessing an individual child's likelihood of developing myopia, eyecare practitioners can delve deeper into the parent's ocular histories and establish their age of myopia onset. If it is before age 12, this could help to highlight children who are at risk of becoming myopic earlier, and as such will benefit from early myopia management intervention.

Myopia in parents may influence myopia development in children by pre-disposing children to becoming myopic before school-age.  However, further research could tell us the extent of the influence of parental myopia in myopia development, and if this varies across different ethnicities.

Title: Association of Parental Myopia With Higher Risk of Myopia Among Multiethnic Children Before School Age

Authors: Xuejuan Jiang, Kristina Tarcy-Hornoch, Susan A. Cotter, Saiko Matsumura, Paul Mitchell, Kathryn A. Rose, Joanne Katz, Seang-Mei Saw, Rohit Varma

Purpose: To investigate the association of parental myopia with refractive error and ocular biometry in multiethnic children aged 6 to 72 months.

Methods: This cohort study pooled data from children in 3 population-based studies with comparable design from the US, Singapore, and Australia. Parental myopia was defined as the use of glasses or contact lenses for distance viewing by the child's biological parent(s). Multivariable regressions were conducted to assess the association of parental myopia. Data were collected from 2003 to 2011 and analyzed from 2017 to 2019. Cycloplegic refraction and prevalence of myopia (spherical equivalent refractive error of≤−0.5 diopters [D]) in the more myopic eye.

Results: The analysis cohort included 9793 children, including 4003 Asian, 2201 African American, 1998 Hispanic white, and 1591 non-Hispanic white participants (5106 boys [52.1%]; mean [SD] age, 40.0 [18.9] months). Compared with children without parental myopia, the odds ratios for early-onset myopia were 1.42 (95% CI, 1.20-1.68) for children with 1 parent with myopia, 2.70 (95% CI, 2.19-3.33) for children with 2 parents with myopia, and 3.39 (95% CI, 1.99-5.78) for children with 2 parents with childhood-onset myopia. Even among children without myopia, parental myopia was associated with a greater ratio of axial length to corneal curvature radius (regression coefficient for myopia in both parents, 0.023;< .001) and more myopic refractive error (regression coefficient for myopia in both parents, −0.20 D;< .001). Effects of parental myopia were observed in all 4 racial/ethnic groups and across age groups except those younger than 1 year. However, parental myopia was not associated with the age-related trends of refractive error (regression coefficient for children without parental myopeia, 0.08; for children with 2 parents with myopia, 0.04;= .31 for interaction) and ratio of axial length to corneal curvature radius (regression coefficient for children without parental myopia, 0.031; for children with 2 parents with myopia, 0.032;= .89 for interaction) beyond infancy.

Conclusions: Parental myopia, especially childhood-onset parental myopia, was associated with a greater risk of early-onset myopia in Asian, Hispanic, non-Hispanic white, and African American children. The observed associations of parental myopia in children as early as 1 year of age and in children without myopia suggests that genetic susceptibility may play a more important role in early-onset myopia and that parental myopia may contribute to myopia in children by setting up a more myopic baseline before school age.