Quantitative anatomical differences in central corneal thickness values determined with scanning-slit corneal topography and noncontact specular microscopy.

Purpose: This study was designed to analyze the differences in central corneal thickness values determined with noncontact specular microscopy and scanning-slit corneal topography. The measurements were performed on the same eye.

Methods: We analyzed the central corneal thickness values of 93 patients (n = 93) by means of noncontact specular microscopy (Topcon SP-2000P noncontact specular microscope, Topcon Corp., Tokyo, Japan) and scanning-slit corneal topography (Orbscan Topography System II, Orbscan Inc., Salt Lake City, UT). One experienced physician performed 3 consecutive central corneal thickness measurements with both devices.

Results: The central corneal thickness values obtained by means of Orbscan pachymetry were 17 +/- 2.7 (range, 12-24) microm greater. A significant correlation was observed between scanning-slit corneal topography and noncontact specular microscopy (Pearson correlation coefficient, r = 0.976; P < 0.001).

Conclusions: Researchers should know of the existence of this difference between noncontact specular microscopy and Orbscan pachymetry when interpreting central corneal thickness values.