J Korean Ophthalmol Soc.  2012 May;53(5):618-625.

Comparison of Corneal Curvatures Obtained with Different Devices

• Kim S
• Chung SK

Abstract

PURPOSE
To evaluate device efficacy using the corneal curvature value.
METHODS
Prospectively, 35 patients (70 eyes) were enrolled in the present study. Three sets of corneal curvature values were obtained using the autorefractor (RK-F1(R)), manual keratometer (OM-2(R)), partial coherence interferometry keratometer (IOL Master(R)), wavefront analyzer (KR-1W(R)), and videokeratography (Orbscan II(R)). Repeatability of each device was evaluated by coefficient of variation, standard deviation, and intraclass correlation coefficient. RM-ANOVA on ranks was used to compare the differences in corneal curvatures among the devices. The Bland-Altman plot was performed to assess measurement agreement among the devices.
RESULTS
The coefficient of variation values from each device ranged from 2.92% (IOL master(R)) to 3.06% (Orbscan II(R)), and the values of intraclass correlation coefficient ranged from 0.965 (KR-1W(R)) to 0.997 (IOL master(R)). Compared with the manual keratometer, there was a maximum corneal curvature difference of 1.23 D in KR-1W(R), while the other devices had differences less than 0.82 D.
CONCLUSIONS
When assessing corneal curvature, the repeatability values were similar among the 5 devices, although a difference greater than 1 D was observed when comparing the KR-1W(R) to the manual keratometer.

Keyword

Corneal curvature; Keratometry

MeSH Terms

Corneal Topography
Humans
Interferometry
Prospective Studies

Figure

• 

  Figure 1 Bland-Altman plots showing differences in corneal curvature measurements between devices. The upper and lower dashed lines indicate 95% limits of agreement and the solid line indicates the mean.

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