Abstract
Purpose: :
To compare corneal topography in keratoconus with corneal topographers which employ three different technologies.
Methods: :
Subjects included in the study were fifteen eyes of 36 patients with keratoconus (keratoconus suspect: 6, mild: 13, moderate: 22, and severe: 9). Topographic measurements was made using Placido-based (TMS-4), Scheimpflug-based, (Pentacam HR), and optical coherence tomography-based (SS-1000) cornea topographers for the subjects. Rate of agreement for the appearance of axial power maps and axial power at the center were compared among three instruments. Central corneal thickness using Pentacam HR was compared with that using SS-1000.
Results: :
The rate of agreement among three instruments for appearance of axial maps in keratoconus suspect, mild, moderate, and severe were 90%, 88%. 85%, and 68%, respectively. There were no significant differences in central axial power or central corneal thickness for keratoconus suspect to moderate cases. Although there was a good correlations in central axial power between Pentacam and SS-1000 (r= 0.96) in severe keratoconus, central axial power with TMS-4 was significantly lower than those with the others (P <0.001, ANOVA repeat measure), and there was a significant difference in central corneal thickness between Pentacam (399±27) and SS-1000 (355±32).
Conclusions: :
Three different corneal topographers may indicate consistent results at least in axial power maps or corneal thickness for keratoconus suspect to moderate keratoconus. However, the topographic data are not always in agreement among three devices in severe keratoconus.
Keywords: keratoconus • refraction • cornea: clinical science