J Korean Ophthalmol Soc.  2012 Oct;53(10):1432-1437.

Comparison of Anterior and Posterior Elevation, and Sagittal Curvature between Keratoconus and Normal Cornea

• Lee JS
• Lee SW
• Lee SM
• Lee MH

Abstract

PURPOSE
To compare changes of anterior and posterior corneal elevation, and sagittal curvature according to the severity of keratoconus and to compare differences between keratoconus and normal cornea.
METHODS
A total of 81 eyes diagnosed with keratoconus and 20 eyes of normal subjects were evaluated with a Pentacam Scheimpflug camera. The keratoconus eyes were divided into 3 groups according to mean keratometer (K): mild (K < or = 47.0 diopters (D)), moderate (47.0 to 52.0 D), and severe (52.0 D> or =). The following parameters were obtained to evaluate the correlation of keratoconus: corneal thickness, anterior and posterior corneal elevation, and sagittal curvature.
RESULTS
Out of 81 keratoconus eyes, 56 eyes were mild, 12 eyes were moderate, and 13 eyes were severe keratoconus. The mean central corneal keratometer, anterior and posterior corneal elevation, and sagittal curvature of the keratoconus eyes were 49.7 D, 22.07 microm, 38.16 microm, 52.76 D and the values increased statistically compared to the normal eyes. Furthermore, the values increased significantly with the severity of keratoconus. ROC curve analysis showed the estimated meaningful value for anterior and posterior corneal elevation and sagittal curvature of keratoconus for diagnosis; there were no diagnostic values for corneal thickness and refractive power.
CONCLUSIONS
The index of 5.5 microm for mean anterior elevation, 12.5 microm for mean posterior elevation, and 44.5 microm for mean sagittal curvature using the Pentacam(R) are useful to diagnose keratoconus. Variation of anterior and posterior elevation, and sagittal curvature measured by Pentacam(R) are useful in understanding the process of keratoconus.

Keyword

Anterior elevation; Keratoconus; Pentacam; Posterior elevation; Sagittal curvature

MeSH Terms

Cornea
Eye
Keratoconus
ROC Curve

Figure

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  Figure 1 Comparison of parameters of Pentacam® (OCULUS, Germany) in keratoconic and normal eyes.(A) Keratometry. (B) Corneal thickness. (C) Anterior and posterior elevation. (D) Sagittal curvature.

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  Figure 2 Receiver operating characteristic (ROC) graph showing the sensitivity and specificity of the various corneal measurements. The closer the line to the left-hand side of the graph, the higher the sensitivity and specificity for keratoconus.

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