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Short-term repeatability of hand-held keratometry measurements
J A Shin1, R E Manny, R N Kleinstein
1Southern California College of Optometry, Fullerton, USA.
Summary
The Alcon Auto-Keratometer offers repeatable corneal curvature measurements in children. Averaging two readings ensures reliable results within +/-0.50 D for refractive error studies.
Area of Science:
- Ophthalmology
- Optometry
- Pediatric Eye Care
Background:
- Corneal curvature is a key factor in refractive error development.
- The Alcon Auto-Keratometer is used in the CLEERE Study to measure corneal curvature in schoolchildren.
- Previous research validated the Alcon Auto-Keratometer's accuracy but not its repeatability.
Purpose of the Study:
- To assess the repeatability of the hand-held Alcon Auto-Keratometer for measuring anterior corneal curvature.
- To determine the optimal number of readings for achieving reliable measurements.
- To establish the short-term agreement of the instrument in a pediatric population.
Main Methods:
- Sixty children participated in the study across two optometry clinics.
- Two sets of five hand-held keratometry measurements were taken on each child's right eye.
- Measurements were repeated at least 10 minutes apart by the same investigator at each site.
Main Results:
- Mean differences in corneal curvature measurements between occasions were not statistically significant.
- Averaging the first two readings significantly improved repeatability, especially for the steep meridian.
- The 95% limits of agreement for the average of two readings were within +/-0.39 D for meridians and +/-0.24 D for vector components.
Conclusions:
- The Alcon hand-held keratometer demonstrates good repeatability for corneal curvature measurements.
- A short-term agreement within +/-0.50 D is achievable.
- Manually averaging two consecutive measurements is essential for obtaining reliable results.