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August 1989

Accuracy and Precision of Keratometry, Photokeratoscopy, and Corneal Modeling on Calibrated Steel Balls

Author Affiliations

From the Department of Ophthalmology, Emory University School of Medicine (Drs Hannush and Waring and Mss Crawford and Gemmill), and the Department of Epidemiology and Biostatistics, Emory University (Messrs Lynn and Nizam), Atlanta.

Arch Ophthalmol. 1989;107(8):1235-1239. doi:10.1001/archopht.1989.01070020301043

• Surgical manipulation of corneal shape requires an accurate and precise method of measuring anterior corneal curvature from apex to limbus. We evaluated the accuracy and precision of the Bausch & Lomb Keratometer, Kera Corneascope, and Computed Anatomy Corneal Modeling System by measuring comparable locations on four calibrated steel test balls. The Keratometer and Corneal Modeling System were more accurate and precise than the Corneascope. No statistically significant difference was found between the Keratometer and Corneal Modeling System with respect to accuracy or precision. In addition, the accuracy and precision of all 31 rings of the Corneal Modeling System were studied. Rings 2 through 26 were read accurately and precisely within ±0.25 diopter on three of the four balls. Values on the steepest ball were within ±0.37 diopter.

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