Pre-myopia is a formal clinical category defined by the IMI — not just 'not yet myopic.' The IMI 2025 Digest substantially updates the evidence for identifying high-risk children and intervening before onset.
"A refractive state of an eye of ≤+0.75 D and >−0.50 D in children where a combination of baseline refraction, age, and other quantifiable risk factors provide a sufficient likelihood of the future development of myopia to merit preventative interventions." — IMI 2025 Digest, Tahhan N et al., Invest Ophthalmol Vis Sci. 2025;66(12):27 (PMC12448141)
The most impactful clinical moment in a child's myopia journey is the period before myopia develops. The IMI 2025 Digest makes this explicit: delaying myopia onset by even 1 year may have greater lifetime benefit than multiple years of progression control with current modalities. A child who becomes myopic at age 7 has far more growth years ahead than one who becomes myopic at 12 — and is far more likely to reach high myopia (≥−6.00D) with its associated lifetime complications.
Yet the final clause of the pre-myopia definition — "to merit preventative interventions" — has historically been the most neglected in clinical practice. The IMI 2025 Digest explicitly notes this omission and reports that the evidence for direct intervention in pre-myopic children is now strong enough to act.
Cycloplegic spherical equivalent refractive error is the single strongest predictor of future myopia onset in children — stronger than parental myopia, outdoor time, or near work history. "Hyperopic reserve" refers to the protective buffer of remaining hyperopia that an age-appropriate child should have. As this reserve depletes — the eye grows longer and the refraction approaches zero — the risk of crossing into myopia escalates rapidly.
The IMI's +0.75D upper threshold was based on the CLEERE study (US, multi-ethnic, 4,512 children aged 6–11). However, the IMI 2025 Digest explicitly states that Chinese children appear to need a greater hyperopic reserve than European children to avoid becoming myopic. A study of over 870,000 Chinese children by Chen et al. (J Glob Health 2023) found that myopia risk increased rapidly when spherical equivalent refraction fell below +1.50D — regardless of age and sex. This +1.50D threshold is now cited in the IMI 2025 Digest as an ethnicity-relevant reference value for Asian populations.
A key conceptual update in the IMI 2025 Digest is the distinction between risk factors (background characteristics associated with higher probability of myopia) and predictive factors (measurable at a specific point in time and used to estimate near-term risk). This distinction matters clinically:
A child with many background risk factors but a strongly hyperopic refraction for their age may have a lower near-term risk than a child with fewer risk factors but a low hyperopic reserve. The IMI 2025 Digest emphasises that predictive models incorporating current refraction are more clinically useful than checklists of risk factors alone.
Outdoor time: The strongest and most consistently supported preventive intervention. The IMI 2025 Digest cites a Taiwan RCT in pre-myopic children aged 7–11 where outdoor recess promotion reduced myopia incidence from 37.8% to 19.6%. Multiple systematic reviews confirm relative reductions in myopia incidence of 16.5–50% with outdoor time interventions. Recommended: ≥90 minutes per day, and ideally ≥120 minutes (Taiwan national programme target).
Low-dose atropine: The IMI 2025 Digest reports that children receiving 0.05% atropine were half as likely to become myopic in a 2-year RCT compared with placebo. Low-dose atropine (0.01%) is also now being evaluated for onset delay in pre-myopes, though evidence is more limited at this concentration for this indication. The IMI notes emerging evidence supporting this use.
RLRL therapy: Emerging evidence cited in the IMI 2025 Digest supports RLRL therapy for delaying myopia onset in high-risk children, though long-term data and safety evidence remain limited outside China.
HAL spectacles: A 2024 RCT in Chinese pre-myopic children found that HAL spectacles slowed axial elongation in low-hyperopic children (plano to +2.00D) compared with single-vision lenses over 12 months. This positions HAL lenses as a potential early intervention tool even before myopia onset.