The Normal Emmetropic Eye
A healthy eye matches its length to its optical power.
- 23-24mm: Typical axial length (placeholder reference range)
- ~0 D: Refractive state (placeholder emmetropia)
- at focus: Retina position (placeholder alignment)
- birth+: Onset age (placeholder growth window)
Emmetropization
Eye growth normally self-calibrates focus onto the retina.
Progressive Axial Elongation
Excess axial growth stretches the globe beyond normal limits.
- 24-26mm: Myopic range (placeholder progression band)
- near work: Growth driver (placeholder risk factor)
- 6-16 yrs: Typical age (placeholder onset window)
- 0.1-0.4mm: Annual growth (placeholder yearly rate)
Scleral stretching
The posterior sclera thins and stretches over time.
Focal Point Anterior to Retina
Light rays cross to a point before reaching the retina.
- myopic: Defocus type (placeholder optical term)
- ~2.5 D: Shift per mm (placeholder diopter rule)
- minus lens: Correction (placeholder optical fix)
- blur far: Symptom (placeholder complaint)
Ray convergence
Rays converge early then diverge before hitting the retina.
Blurred Distance Vision
A defocused blur circle replaces a sharp retinal image.
- grows w/ D: Blur circle (placeholder size rule)
- often clear: Near vision (placeholder contrast)
- reduced acuity: Far vision (placeholder symptom)
- glasses/CL: Fix (placeholder correction)
Retinal image quality
Blur circle size scales with how far focus misses the retina.
Elongation Rate as a Progression Marker
Faster yearly elongation predicts higher long-term myopia risk.
- >0.25mm/yr: Fast progressor (placeholder threshold)
- <0.10mm/yr: Slow progressor (placeholder threshold)
- 6-12 yrs: Peak risk age (placeholder window)
- biometry: Monitoring tool (placeholder method)
Tracking growth
Repeated axial length measurements reveal the progression trend.