Is -3.50 Myopia Bad?
Short answer: −3.50D is moderate myopia, and it deserves attention — especially in children. The axial length at this prescription (roughly 25.2–25.7mm) is approaching the range where progression monitoring and management become important priorities.
Where -3.50 sits in the risk spectrum
Myopia severity is better understood through axial length (the physical length of the eye in millimetres) than through the diopter number alone. Two people can have the same prescription from different amounts of axial elongation — and axial length is what determines long-term structural risk, not the diopter number itself.
| Prescription | Approx. axial length | Structural risk category |
|---|---|---|
| -1.00D | ~24.2mm | Low |
| -2.00D | ~24.7mm | Low–Moderate |
| -3.00D | ~25.2mm | Moderate |
| -4.00D | ~25.8mm | Moderate–High |
| -5.00D | ~26.1mm | High |
| -6.00D | ~26.6mm | High (IMI threshold) |
| -8.00D | ~27.5mm | Very High |
| -10.00D | ~29.0mm | Extreme |
AL–refraction mapping is approximate (±2–3D individual variation). Based on Flitcroft 2012; Tideman et al. 2016. Your row is highlighted.
Clinical perspective
Axial length at −3.50D is approximately 25.2–25.7mm. While still below the high-myopia structural threshold, the rate of change at this level matters significantly. A child at −3.50D progressing 0.50D/year is on a trajectory for high myopia by their mid-teens without management.
For parents: what this means for a child at -3.50
If your child has reached −3.50D and is under 14, myopia management should be an active conversation with their optometrist — not something to revisit at the next prescription change.
What to do at -3.50
Management is indicated for children at this level with ongoing progression. The treatment modality depends on age, lifestyle, and prior response.
Calculate your exact progression rate
Enter age and two axial length measurements. Get progression rate, AL percentile, and projected prescription at age 18 — with and without treatment.
Check progression now →This page is for educational purposes and does not constitute medical advice. Diopter-to-axial-length conversions are approximations (±2–3D individual variation). MyopiaTracker is a decision-support tool — not a diagnostic device. Consult a qualified optometrist or ophthalmologist for personalised advice.