Race as a predictor of myopia progression in paediatric patients

Authors: Donald S Fong(1); Tiffany Luong(2); Yu-Hsiang Shu(2); Bobeck Modjtahedi(2); Nozhat Choudry(3); Yoko Tanaka(3) & Claudia Nau(2)

1. Ophthalmology, Kaiser Permanente Southern California, Baldwin Park, California, United States
2. Research & Evaluation, Kaiser Permanente Southern California, California, United States
3. Santen Canada, Ontario, Canada

Date: June 2020

Source: ARVO 2020 Abstracts - video presentation

Myopia has multi-factorial causes with both nature and nurture contributing.  The ‘nurture’ causes are ones we can attempt to control, but ‘nature’ causes need careful investigation if we are to confidentially pick out those at greater risk.

The authors used a retrospective cohort study to examine any differences in progression rate with different ethnicities and greater understand who may be at increased risk of myopic progression.

Study outcomes revealed differences in myopic progression over time between the different racial groups, with the East/Southeast and South Asian children having higher myopia and their myopia progressing faster compared to the white children

Allowing for different sample sizes and inclusion criteria, results from other studies have made similar race/ethnicity links with myopia prevalence.

• A CHASE study conducted in the UK in 2010 found that children of South Asian descent showed the highest prevalence of myopia compared to other race/ethnicity such as black African Caribbean and white children.¹
• The Sydney Myopia Study found that the East Asian children in their random sample had a higher prevalence of myopia.²

For everyday myopic management practice, the findings from this study into the relationship between race and myopia reminds us that certain children will benefit from effective intervention as early as possible, especially if we are aware they may progress faster than other racial groups.

• Meeting abstract so not fully peer-reviewed
• Race distribution: Latino children were over represented at 54%, compared to 15% white, 9% black, 9% East/Southeastern Asian and 2% South Asian.
• Children’s ages: The children’s age range for the study was 5-11 yrs, suggesting primary school age.
  • It would be interesting to see what the rates of progression were beyond 11yrs, perhaps into the late teens.
  • A second study could explore if there is a different stabilising age for each racial group and if progression is influenced by a change in studying or physical activities with increasing age and if race still came into play at that stage.
• Parents refractive error and genetic link: The children were grouped for analysis according to their stated race/ethnicity and language spoken as this was the main aim of the study.
  • The abstract doesn’t state if the refractive status of the parents was included too.  It can be helpful to know this when assessing a child’s likelihood of myopia and could provide an extra confirmation of their risk.
  • The confirmation of racial susceptibility to myopia from Fong et al may also demonstrate the genetic aspect to myopia.
  • There can be a 6-fold increased risk of a child being myopic if both parents are also myopic.³
• Contributing factors: The results, understandably, were adjusted for confounding factors such as screen time and outdoor activities to help isolate any racial link.
  • Knowing how likely each factor could either increase progression (e.g, prolonged near work) or slow progression (e.g, time spent outdoors) alongside the racial link and societal/cultural differences would help complete an overall picture.
• Society/culture differences: Once a correlation between a given race and the risk of myopia is established, the next step could be to consider why this occurs for given groups.
  • Educational expectations, socio-economic factors, the physical environment of the country of residence and the opportunity for outdoor sports activities have been well discussed previously.

Described in their ARVO poster/paper, the authors attempted to isolate race as a factor for myopic progression by following 11,000 children over 5 years to assess their progression over time and discover any differences with race/ethnicity. Adjusted for gender, screen time and physical activity, among other confounding factors to compare race alone, their results showed that South Asian and East/Southeast Asian children made up the largest proportion of children (19%) with myopia in the refractive range group having  <-3.00D and ≥ -6.00D (spherical equivalent). By comparison, within the same refractive group, the lower 14% proportion comprised white and Latino children.

The baseline refractive error was similar across all of the groups, with white children having a mean value of -1.90D at the lowest end of the range and South Asian and East/Southeast Asian children having a mean value of -2.10D and -2.20D respectively.

Over the 5 years that the children were followed, the East/Southeast Asian children not only showed more myopia over time but progressed faster over this period, too, particularly for children group that had their myopia diagnosed between the ages of 6 and 8 years old.

The average yearly change between the baseline measurement and the last time the refractive error was measured showed the black and latino children had the lowest change at -0.30D yearly, white children had an average -0.4D yearly change and the South Asian and East/Southeast Asian children had a -0.50D change.