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An evaluation of keratometry in 6-year-old children
Son C Huynh1, Tung Q Mai, Annette Kifley
1Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, Australia.
Insights
Both the IOLMaster and RK-F1 AutoRef-Keratometer show high repeatability for pediatric keratometry. However, slight systematic differences exist between the instruments, impacting corneal power measurements in children.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Pediatric Optometry
Background:
- Accurate keratometry is crucial for monitoring refractive development in children.
- Assessing the repeatability and comparability of different keratometry devices is essential for reliable longitudinal studies.
Purpose of the Study:
- To evaluate the repeatability and comparability of keratometry measurements obtained from the IOLMaster and RK-F1 AutoRef-Keratometer in a pediatric population.
- To determine systematic differences between these two instruments for assessing corneal power in children.
Main Methods:
- Analysis of keratometry data from 447 six-year-old children participating in the Sydney Myopia Study.
- Calculation of 95% limits of repeatability (LR) and 95% limits of agreement (LA) for both instruments.
- Comparison of corneal power measurements along the flattest and steepest meridians.
Main Results:
- Both IOLMaster and RK-F1 demonstrated high repeatability for repeat measurements on individual instruments.
- No systematic differences were found for repeat measurements within each device.
- Significant systematic differences were observed between the IOLMaster and RK-F1, with the IOLMaster yielding steeper readings.
Conclusions:
- The IOLMaster and RK-F1 are highly repeatable for pediatric keratometry, suitable for tracking corneal curvature changes over time.
- Clinicians and researchers should be aware of the small but significant systematic differences between these instruments when comparing measurements.
- These findings support the use of either device for monitoring refractive development, with careful consideration of inter-device variability.
Purpose:
To evaluate the repeatability and comparability of keratometry measured by both the IOLMaster and RK-F1 AutoRef-Keratometer in children.
Methods:
Keratometry results from a sample (n = 447) of 6-year-old children who were examined in the Sydney Myopia Study were analyzed. Corneal power was analyzed along the flattest and steepest meridians to determine if there were any systematic differences between repeat measurements or between the two instruments. The 95% limits of repeatability (LR) and 95% limits of agreement (LA) (mean difference +/- 1.96 x standard deviation of differences) were calculated.
Results:
There were no systematic differences in repeat measurements for each instrument. For the IOLMaster, mean difference of the flattest corneal meridian was -0.01 (D) (P = 0.3, 95% LR, -0.22, 0.21 D) and of the steepest corneal meridian, 0.01 D (P = 0.3, 95% LR, -0.35, 0.38 D). For the RK-F1, mean difference of the flattest corneal meridian was -0.02 D (P = 0.3, 95% LR, -0.25, 0.21 D); and of the steepest corneal meridian, 0.00 D (P = 0.9, 95% LR, -0.39, 0.39 D). Systematic differences, however, were found between the two instruments. The IOLMaster gave significantly (P < 0.0001) steeper readings than the RK-F1 for both the flattest corneal meridian, 0.29 D (95% LA, -0.08, 0.66 D), and the steepest corneal meridian, 0.18 D (95% LA, -0.29, 0.65 D).
Conclusions:
Keratometry was highly repeatable for both the IOLMaster and RK-F1 instruments when used in young children. These instruments would be suitable for use in monitoring changes of corneal curvature over time. Small significant systematic differences in keratometry between the two instruments were also found.