Parental Myopia as a Non-Modifiable Risk Factor: How Important Is It?

Share

Tweet

Share

Share

Email

October 1, 2024

By Liesl Forward, BOptom

Parental myopia is a well-established risk factor for the development of myopia in children. It stands with age and ethnicity as non-modifiable risk factors, in contrast to modifiable risk factors such as outdoor time and near work. Clinicians can use the refractive status of a child’s parents to guide the management of myopic or potentially myopic children. 

What Do We Need to Know About Parents’ Vision?
Evidence consistently shows that the risk of children developing myopia increases with each myopic parent they have.¹ For instance, one study found that compared to children without myopic parents, children with one myopic parent had twice the odds of becoming myopic, and children with two myopic parents had five times the odds.² In children who are already myopic, those with myopic parents go on to progress faster.³

The magnitude of parental myopia is also important. The Guangzhou Twin Eye Study compared groups of children with combinations of non-myopic, moderately myopic, and highly myopic parents.⁴ In general, children with highly myopic parents were the most at risk of myopia development and progression, followed by those with moderately myopic parents and then those without myopic parents. However, if children had only one myopic parent but this was high in magnitude, the children were slightly more likely to develop myopia or progress than children with two moderately myopic parents. 

The combination of the numerical count of myopic parents and their level of myopia can, therefore, be used by clinicians to gauge how likely a child is to develop myopia. Review cycles and timing of any myopia control initiation can then be set appropriately.

How ‘Non-Modifiable’ is Parental Myopia?
Genetics certainly imparts some of the risks that parental myopia poses for their child’s vision development. Myopia occasionally occurs secondary to systemic syndromes (e.g., Stickler syndrome, Marfan syndrome), and some studies have identified autosomal dominant or X-linked inheritance patterns in particular families.⁵ However, the majority of childhood myopia appears to be polygenic.⁶ Genes identified to be associated with myopia are related to ocular anatomy (such as the cornea, lens, and retina) as well as non-ocular factors such as circadian rhythm (which may influence the emmetropization process).⁷ Polygenic risk scores (PRSs) are an emerging method of quantifying an individual’s chances of myopia development. However, the identification of parental myopia in clinical history remains a proxy for this in mainstream clinical care.⁶

However, despite a strong genetic component, some studies have suggested that the environment may play an additional role in parents passing on myopia to their children. An analysis of the interaction of environmental and genetic risk for myopia development in children in the Netherlands found that parental myopia was statistically associated with both factors.⁸ This may be because children share an environment with their parents, such as reduced outdoor time or focus on educational attainment with high levels of near work. An opportunity may exist for clinicians to advise about changes in shared family lifestyle rather than considering the risk posed by parental myopia to be purely non-modifiable.

Should Parental Myopia Affect Myopia Management?
While the heightened risk of myopia for those with a family history leads clinicians to consider myopia control more strongly in these patients, it would be prudent to know if parental myopia alters the efficacy of myopia control efforts. 

Clinical trials have established the efficacy of myopia control methods, and these have now found widespread use, including low-dose atropine, multifocal contact lenses, orthokeratology, and peripheral defocus spectacles. Many, though not all, of these trials reported parental myopia as a baseline characteristic of their study cohort. The subjects of the LAMP study had a mean parental refractive error that was strongly myopic,⁹ while the majority of subjects of the MiYOSMART trial had two myopic parents.¹⁰ This can give clinicians confidence that these treatment modalities (and others with similar study populations) are applicable even to children with a higher risk profile due to family history. 

To date, however, there is little research into whether differential treatment efficacies exist for children with and without parental myopia. Children who progress despite treatment have been found to be more likely to have parental myopia.¹¹ Further analysis of this question in larger cohorts could allow clinicians to adjust their expectations for, and therefore management of, such patients. 

Conclusions
Parental myopia does heighten the risk for myopia in children. Nevertheless, by being aware of which children are most at risk, the genetic and environmental factors involved, and emerging research into myopia control efficacy, clinicians can intervene appropriately to mitigate this. 

 

Liesl Forward is an Australian clinical optometrist who graduated from the University of Melbourne. After working in regional private practice, she now works for the Australian College of Optometry in Melbourne. She has strong interests in ocular disease management and public health and is also involved in clinical teaching and outreach eye care.

 

Some products covered in Review of Myopia Management are prescribed off-label in the United States because they are not FDA-approved for slowing the progression of myopia in children.

 

References 

1. Yu M, Hu Y, Han M, et al. Global risk factor analysis of myopia onset in children: A systematic review and meta-analysis. PLoS One. 2023;18(9):e0291470. Published 2023 Sep 20. doi:10.1371/journal.pone.0291470.
2. Jones LA, Sinnott LT, Mutti DO, et al. Parental history of myopia, sports, and outdoor activities, and future myopia. Invest Ophthalmol Vis Sci. 2007;48(8):3524-32.
3. Varošanec AM, Marković L, Sonicki Z. The CroMyop study: myopia progression in Croatian children and adolescents-a 15-year retrospective analysis. Front Med (Lausanne). 2024;11:1405743. Published 2024 May 31. doi:10.3389/fmed.2024.1405743.
4. Liao C, Ding X, Han X, et al. Role of Parental Refractive Status in Myopia Progression: 12-Year Annual Observation From the Guangzhou Twin Eye Study. Invest Ophthalmol Vis Sci. 2019;60(10):3499-3506. doi:10.1167/iovs.19-27164.
5. Cai XB, Shen SR, Chen DF, Zhang Q, Jin ZB. An overview of myopia genetics. Exp Eye Res. 2019;188:107778. doi:10.1016/j.exer.2019.107778.
6. ‌Wang YM, Lu SY, Zhang XJ, Chen LJ, Pang CP, Yam JC. Myopia Genetics and Heredity. Children (Basel). 2022;9(3):382. Published 2022 Mar 9. doi:10.3390/children9030382.
7. Hysi PG, Choquet H, Khawaja AP, et al. Meta-analysis of 542,934 subjects of European ancestry identifies new genes and mechanisms predisposing to refractive error and myopia. Nat Genet. 2020;52(4):401-407. doi:10.1038/s41588-020-0599-0.
8. Enthoven CA, Tideman JWL, Polling JR, et al. Interaction between lifestyle and genetic susceptibility in myopia: the Generation R study. Eur J Epidemiol. 2019;34(8):777-784. doi:10.1007/s10654-019-00512-7.
9. Yam JC, Jiang Y, Tang SM, et al. Low-Concentration Atropine for Myopia Progression (LAMP) Study: A Randomized, Double-Blinded, Placebo-Controlled Trial of 0.05%, 0.025%, and 0.01% Atropine Eye Drops in Myopia Control. Ophthalmology. 2019;126(1):113-124. doi:10.1016/j.ophtha.2018.05.029.
10. Lam CSY, Tang WC, Tse DY, et al. Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial. Br J Ophthalmol. 2020;104(3):363-368. doi:10.1136/bjophthalmol-2018-313739.
11. Loh KL, Lu Q, Tan D, Chia A. Risk factors for progressive myopia in the atropine therapy for myopia study. Am J Ophthalmol. 2015;159(5):945-949. doi:10.1016/j.ajo.2015.01.029