Myopia prevention is as important as treatment

Paper title: Myopia: An ounce of prevention is worth a pound of cure 

Authors: Mark A. Bullimore (1), Noel A. Brennan (2) 

1. College of Optometry, University of Houston, Houston, Texas, USA
2. Johnson & Johnson Vision, Jacksonville, Florida, USA

Date: Oct 2022

Reference: Bullimore MA, Brennan NA. Myopia: An ounce of prevention is worth a pound of cure. Ophthalmic Physiol Opt. 2023 Jan;43(1):116-121 

[Link to abstract]

The prevalence of myopia is increasing, with one study finding nearly half of European young adults are myopic.¹ The higher the myopia, the more the concern for future visual impairment later in life. Studies have shown that the age of myopia onset can be a predicting factor for the final level of myopia,^2-6 and this can be lowered not only by myopia control treatment but by delaying the onset altogether.^7,8

This study investigated the influence of the age of myopia onset on the ultimate recorded myopia level. The authors collated data from the following ten studies which had examined myopia progression and presented the final recorded myopia level as a function of the age of onset:

• 3 prospective cohort studies: Chua et al (SCORM study), Singapore; Hu et al, China and Jones-Jordan et al (CLEERE study), USA^5,9,10
• 4 retrospective studies: Mantyjarvi et al, Finland; Verkicharla et al, South India; Polling et al (DREAM study), Netherlands and Qin et al, China^2,11-13
• 2 cross-sectional studies: Iribarren et al, Argentina and Williams et al, UK^3,4
• 1 cohort study: Parssinen et al, Finland¹⁴

Using the data from the featured studies, regression lines were plotted for each cohort to reflect the final recorded level of myopia as a function of age of onset for East Asians and non-East Asians. A single value was used for all studies apart from Hu et al and Polling et al where there was more than one age group.

For the East Asian studies, the slope values were between 0.68 and 0.97D per year. The lower value is for the Chua et al study and is lower than the value found in the original study to allow direct comparison across age groups.

For 6 of the 7 non-East Asian studies, the slope values were flatter; between 0.23 and 0.50D per year. The slope for the seventh non-East Asian study showed 0.87D per year.

The plotted slope values also show that European children developing myopia at 8yrs will have a mean myopia of -4.00D by age 17yrs. For East Asian children, the mean myopia was at least -6.00D by the same age. These results, and the demonstration of steeper plots for East Asians, confirm previous findings of rapid progression for East Asians compared to non-East Asians.¹⁵

The authors of this study have applied Benjamin Franklin’s quote of “an ounce of prevention is worth a pound of cure” to myopia development and progression in order to demonstrate the importance of delaying development.

The slope values represent the potential saving of myopia progression for each year of myopia onset delay.

• Each earlier year of onset is associated with approximately -0.75 to -1.00D increased myopia later in life.
• The earlier myopia onset, the higher the chance of increased levels of myopia and the associated risk of visual impairment

Therefore, if myopia could be delayed by one year, an individual’s final myopia level could be reduced by this amount. This appears to be particularly true for East Asian children and although the benefit is lower for non-East Asians, it is still meaningful. 

Current myopia control modalities may need approximately 3yrs to provide the same long-term effect as one year of delayed myopia onset^16-19

• Although slowing of progression is possible, current myopia control methods are not approved to prevent or delay myopia development

Time outdoors has been shown to be associated with reduced myopia incidence and is an ideal approach in limiting myopia development and saving dioptres.^7,20 This is particularly true for younger children who are at risk of fast progression.

The studies featured in this review used different instrumentation, settings and methodologies, meaning the age of onset and final refraction was investigated differently.

• Three prospective studies based it on annual refraction, one clinical trial inferred it from the age of entry to the study and it was based on clinical records in other studies
• Older adult study participants may not have remembered correctly when they first had their myopic correction, and adult myopia progression may also have occurred to influence the final refraction.

Although this makes direct comparison difficult, the slopes were similar for each race and relationship between final myopia and age of onset was consistent across all cohorts.

Title: Myopia: An ounce of prevention is worth a pound of cure 

Authors: Mark A. Bullimore, Noel A. Brennan 

Purpose: Myopia severity has a profound impact on visual impairment in later life. A patient's final level of myopia may be lowered by myopia control, but also by delaying onset. Here, we evaluate the influence of the age of onset on the final recorded level of myopia. 

Methods: Data were extracted from: (1) Three prospective cohort studies of myopia progression in East Asia and the United States where the final recorded level of myopia is presented as a function of the established age of onset. (2) Four retrospective studies of myopia progression in Finland, India, the Netherlands and China and two cross-sectional studies in Argentina and the UK where the age of onset was based on self-report of age at first spectacle prescription. (3) A cohort study of Finnish subjects originally recruited for a clinical trial and followed into adulthood. Subjects were divided into five groups according to age at recruitment that was used as a surrogate for the age of onset. 

Results: Final recorded level of myopia was plotted as a function of age of onset for all studies. Among the three East Asian studies, the slopes are between 0.68 and 0.97 D/year, meaning that each later year of onset is associated with between 0.68 and 0.97 less myopia at the final recorded refraction. For six of the seven non-East Asian studies, the slopes are substantially flatter, with slopes between 0.23 and 0.50 D/year. By contrast, the slope for the Finnish study was 0.87 D/year. Increasing age of final recorded refraction tended to be associated with higher levels of myopia. 

Conclusions: Among East Asians, delaying the onset of myopia by 1 year has the potential to lower the final myopia level by 0.75 D or more-equivalent to 2-3 years of myopia control with existing modalities. The benefit is lower, but meaningful, among non-East Asians. 

[Link to abstract]