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Corneal aberrations measured with a high-resolution Scheimpflug tomographer: repeatability and reproducibility
Colm McAlinden1, Jim Schwiegerling, Jyoti Khadka
1From the Department of Ophthalmology (McAlinden), Singleton Hospital, Swansea Bay University Health Board, Swansea, United Kingdom; College of Optical Sciences (Schwiegerling), University of Arizona, and Department of Ophthalmology & Vision Sciences (Schwiegerling), University of Arizona, Tucson, Arizona, USA; Institute for Choice (Khadka), UniSA Business School, University of South Australia, Healthy Aging Consortium (Khadka), South Australian Health and Medical Research Institute, Adelaide, and Australian College of Optometry (Pesudovs), Carlton, Victoria, SA2 8QA Australia.
The Pentacam HR offers precise elevation and wavefront aberration measurements, with the cornea fine mode yielding the best results. Be mindful of posterior elevation aberration precision, especially for specific Zernike terms.
Area of Science:
- Ophthalmology and optometry
- Optical metrology
Background:
- Accurate measurement of corneal aberrations is crucial for refractive surgery and diagnosing eye conditions.
- The Pentacam HR is a widely used device for anterior segment analysis, but its precision requires thorough evaluation.
Purpose of the Study:
- To evaluate the measurement precision of elevation and wavefront aberrations using the Pentacam HR device.
- To compare the precision across different measurement modes (25-picture, 50-picture, cornea fine).
Main Methods:
- 100 participants' eyes were scanned twice using the Pentacam HR in three measurement modes by one observer.
- A second observer performed scans in the 25-picture mode for reproducibility assessment.
- Repeatability and reproducibility were quantified using the within-subject standard deviation (Sw) from a 1-way ANOVA.
Main Results:
- High precision was observed for higher-order aberration root mean square (RMS) repeatability limits (0.03 μm) across all modes for both elevation and wavefront.
- Most anterior, posterior, and total corneal wavefront Zernike terms showed high precision (repeatability limit of 0.03 μm).
- The cornea fine mode demonstrated the highest precision, while posterior elevation Zernike terms in the 25-picture scan were least repeatable (1.50 μm).
Conclusions:
- The Pentacam HR provides highly precise aberration measurements, particularly with the cornea fine mode and wavefront aberrations.
- Users should be aware of potential precision limitations with posterior elevation aberrations, especially for specific Zernike terms.
- Overall, the device exhibits excellent repeatability and reproducibility for RMS and Zernike aberrations when accounting for tilt and misalignment.
