Will they need glasses?
Myopia (nearsightedness) is highly heritable but strongly modulated by environment. Tell us about both parents and your child's ancestry / lifestyle, and we'll estimate lifetime risk and most likely age of onset.
Shifting outdoor time to 2+ hr/day and screen time to under 2 hr/day drops the lifetime risk to 7% — that's about 7 percentage points lower. The Sherwin 2012 meta-analysis found roughly 2 hours/day outdoors halves the risk of incident myopia in children.
| Parental baseline (0 myopic parents) | 12% |
| Onset / severity bump | ×1.00 |
| Ancestry multiplier | ×1.00 |
| Outdoor time | ×1.00 |
| Screen time | ×1.15 |
| Lifetime myopia probability | 14% |
Why high myopia matters. Above -6.00 D, the eye is elongated enough to raise the lifetime risk of retinal detachment, glaucoma, and myopic maculopathy — the latter is now a leading cause of vision loss in East Asia. Annual eye exams from age 3 are the cheapest, highest-leverage intervention. If your child does become myopic early, ask the pediatric ophthalmologist about low-dose atropine (ATOM 2 / LAMP trials) or dual-focus contact lenses / orthokeratology (MOSAIC) — both can slow progression by 30–60%.
This is a population-level risk model, not a diagnosis. Myopia is genuinely polygenic (200+ loci identified in GWAS) and we're collapsing all of that into a few user-friendly inputs. Two children of identical parents and ancestry can land in very different places.
What we use: parental-myopia twin-cohort baselines (~12% / 25% / 42% lifetime risk for 0 / 1 / 2 myopic parents), an ancestry-specific multiplier, an onset-and-severity bump (earlier-onset parents = higher child risk), and multiplicative environment factors. Outdoor-time effect size is calibrated to Sherwin 2012; screen-time effect is intentionally modest because the literature is mixed.
What we don't do: claim any specific child's outcome, replace a cycloplegic refraction, or factor in a polygenic risk score. High myopia (>-6 D) carries real clinical risk — annual eye exams from age 3 are cheap and high-leverage. Talk to a pediatric ophthalmologist if myopia appears before age 10 or progresses faster than ~0.50 D/year.
Sources: Morgan IG, Ohno-Matsui K, Saw SM. Myopia. Lancet 2012;379:1739-48. Sherwin JC et al. The association between time spent outdoors and myopia in children and adolescents. Ophthalmology 2012;119:2141-51. Pärssinen O, Kauppinen M. Risk factors for high myopia: a 22-year follow-up. Acta Ophthalmologica 2019. ATOM 2, LAMP, and MOSAIC trials on myopia control.