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Wavefront analysis
Anatomy & Optics
Key Points
- •The Hartmann-Shack sensor is the most widely used wavefront aberrometer - measures the wavefront exiting the eye using an array of lenslets and a CCD camera
- •Wavefront aberrations are decomposed into Zernike polynomials - each representing a unique aberration mode (defocus, astigmatism, coma, trefoil, spherical aberration, etc.)
- •RMS error is the summary measure of wavefront deviation; normal HOA RMS for 6 mm pupil is ~0.3–0.5 μm
- •Strehl ratio >0.8 indicates clinically insignificant aberrations (Maréchal criterion); post-LASIK eyes typically have Strehl ratios of 0.1–0.3
- •Wavefront-guided ablation corrects both LOA and HOA; wavefront-optimised ablation only reduces induced spherical aberration (maintains asphericity)
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- Definition
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- Aetiology and causes
- Pathogenesis
- Classification
- Risk factors and associations