Corneal topography using the Holladay Diagnostic Summary

To describe new software developments in videokeratography and illustrate their application in patients with corneal disease or patients who have had keratorefractive surgery.

The Holladay Diagnostic Summary provides 4 maps and 15 corneal parameters for the clinician. The maps include 2 refractive power maps on standard and auto scales, a profile difference map for determining the corneal shape relative to normal asphericity, and a distortion map to display the optical quality of the cornea. The 15 corneal parameters provide quantitative information about the cornea for a 3.0 mm pupil; e.g., effective refractive power, regular astigmatism, asphericity, and predicted corneal acuity. The maps and parameters are used to analyze a calibration ball and five clinical examples.

Patients with diseases such as keratoconus or patients who have had keratorefractive surgery have characteristic changes in the 4 maps and the 15 corneal parameters.

When true refractive power maps, a profile difference map, a distortion map, and 15 corneal parameters are analyzed, characteristic changes are found that can help clinicians recognize and monitor corneal disease and refractive surgery and correlate these changes with patients' visual symptoms.