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Comparison of three computerized videokeratoscopy systems with keratometry
R C Moura1, B L Bowyer, S X Stevens
1Federal University of Sao Paulo, Brazil.
Cornea
|October 2, 1998
Summary
Computerized videokeratoscopy systems show reproducible results within each device. However, significant differences exist between systems, meaning their clinical data should not be interchanged.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Optometry
Background:
- Computerized videokeratoscopy is crucial for corneal topography analysis.
- Evaluating the reproducibility and inter-system agreement of these devices is essential for clinical applications.
Purpose of the Study:
- To compare the reproducibility of three commercial videokeratoscopy systems (EyeSys, TechnoMed C-Scan, PAR Corneal Topography System [CTS]) using normal eyes and calibrated objects.
Main Methods:
- Three videokeratoscopy systems and a manual keratometer were used.
- Calibration spheres and 20 eyes from 10 normal subjects underwent 10 serial examinations on each system.
- Average keratometry (K) within the central 3.0 mm was compared between systems and with manual keratometry.
Main Results:
- All videokeratoscopy systems demonstrated good correlation with each other and manual keratometry for calibration objects.
- EyeSys showed the strongest correlation with manual keratometry (35%), followed by PAR-CTS (25%) and C-Scan (5%).
- Significant differences (p < 0.05) were found between systems when analyzing clinical data, with average K differences <0.35 D.
Conclusions:
- While individual videokeratoscopy systems provide reproducible measurements, significant inter-system variability exists.
- Results from different topography systems should not be assumed to be interchangeable in clinical studies.