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Interferometry and coherence in ophthalmology
Anatomy & Optics
Key Points
- •Interference occurs when two coherent waves superimpose - constructive (in phase → bright) and destructive (out of phase → dark) interference produce measurable fringe patterns
- •Temporal coherence relates to monochromaticity; spatial coherence relates to source size. OCT exploits low temporal coherence (broadband source, short coherence length ~10 μm) for high axial resolution
- •OCT uses low-coherence interferometry: interference occurs only when reference and sample path lengths match within the coherence length → depth-resolved tissue imaging at 5–10 μm axial resolution
- •IOL Master uses partial coherence interferometry (PCI) for non-contact axial length measurement with ±0.01–0.02 mm accuracy, superior to ultrasound A-scan
- •Laser interferometry and PAM assess macular function through media opacities by projecting interference fringes or a miniature Snellen chart directly onto the retina
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- Definition
- Epidemiology
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- Pathogenesis
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