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Corneal Confocal Microscopy: A Novel Non-invasive Technique to Quantify Small Fibre Pathology in Peripheral Neuropathies
Published on: January 3, 2011
Performance in specular reflection and slit-imaging corneal topography.
Boy Braaf1, Michiel Dubbelman, Rob G L van der Heijde
1Rotterdam Ophthalmic Institute (ROI), The Rotterdam Eye Hospital, Rotterdam, The Netherlands.
Summary
Corneal topographers show clinically relevant differences in measuring anterior radius of curvature and total corneal astigmatism. Specular reflection devices offer superior precision compared to slit-lamp instruments for corneal shape analysis.
Area of Science:
- Ophthalmology
- Optometry
- Biomedical Optics
Background:
- Accurate corneal shape and aberration measurement is crucial for refractive error correction.
- Different topographical instruments (Placido-based, Scheimpflug-based) have varying performance characteristics.
Purpose of the Study:
- To compare the performance of two specular reflection topographers (Keratron, VU) and two slit-lamp imaging instruments (Orbscan II, Topcon SL-45) in measuring corneal shape and aberrations.
- To assess the clinical relevance of observed differences for various ophthalmic applications.
Main Methods:
- Corneal height maps of anterior and posterior surfaces were acquired from 34 subjects using all four instruments.
- Corneal shape parameters (radius of curvature, asphericity) and wave aberrations (Zernike convention) were calculated.
- Ray tracing was employed for aberration determination.
Main Results:
- Clinically relevant differences were found in anterior corneal radius of curvature and anterior corneal astigmatism measurements.
- Significant differences were also observed for posterior radius, total corneal astigmatism, and central corneal thickness (CCT).
- Specular reflection topographers demonstrated superior precision (at least double) compared to slit-lamp instruments.
Conclusions:
- Corneal topographers are largely interchangeable for standard spectacle and contact lens fitting, except for anterior radius of curvature.
- Subtle differences in total corneal astigmatism and CCT are clinically relevant for advanced procedures like customized corneal refractive surgery.
