J Korean Ophthalmol Soc.  2004 Jun;45(6):928-935.

Diagnostic Criteria for Keratoconus Using Orbscan II Slit Scanning Topography/Pachymetry System

• Choi HJ
• Kim MK
• Lee JL

Abstract

PURPOSE
To investigate new diagnostic criteria of keratoconus using Orbscan II Slit Scanning Corneal Topography/Pachymetry System. METHODS: Eighty eyes of 45 patients with keratoconus and 100 randomly selected eyes of 50 patients without any ophthalmologic problem were enrolled in this study. Anterior elevation from BFS, posterior elevation from BFS, Sim K (maximum), and thinnest pachymetric value were evaluated using Orbscan II. Values outside 2 standard deviations from the mean value of each parameter were estimated to the upper or lower limits in diagnosing keratoconus. RESULTS: There were significant differences of all parameters of Orbscan II between the keratoconic eyes and the control (p<0.001). Keratoconus could be diagnosed with 86.3% sensitivity and 99.0% specificity when 3 or more criteria were satisfied and with 96.3% sensitivity and 99.0% specificity when 2 or more criteria were satisfied out of the following 4 criteria; anterior elevation from BFS > 23.3 micro meter, posterior elevation from BFS > 49.8 micro meter, Sim K (maximum) > 47.0 D, thinnest pachymetric value < 455.0 micro meter. CONCLUSIONS: Orbscan II can provide useful information in the diagnosis of keratoconus with high sensitivity and specificity.

Keyword

Diagnosis of Keratoconus; Keratoconus; Orbscan II

MeSH Terms

Diagnosis
Humans
Keratoconus*
Sensitivity and Specificity