Abstract
Purpose: :
To compare the central corneal thickness (CCT) measurements obtained by slit-lamp optical coherence tomography (SL-OCT) with those obtained by ultrasound, specular microscopy, and Orbscan. The aim of the study was to compare the accuracy of SL-OCT in measuring CCT compared to other modalities and to study the correlation between them.
Methods: :
Thirty two eyes of 32 subjects with no known ocular disease and best-corrected visual acuity of 20/20 were enrolled in this prospective study. All subjects underwent a complete eye exam. The CCT measurements were obtained using Heidelberg SL-OCT, Konan Noncon Robo specular microscopy, Bausch and Lomb Orbscan and Tomey AL-3000 ultrasound (U/S) pachymetry. Three measurements were made with each instrument by the same operator in all the subjects. Paired t-test was used for comparisons between all instruments.
Results: :
Mean CCT was 546.36 µm by SL-OCT as compared to 548.15 µm (P=0.17), 557.60 µm (P<0.0001), and 550.95 µm (P=0.13) by U/S pachmetry, specular microscopy, and Orbscan (with correction factor), respectively. All modalities had a strong correlation with SL-OCT measurements (Pearson correlation coefficients).
Conclusions: :
This comparative study suggests that SL-OCT can be used interchangeably with ultrasound pachymetry or Orbscan (with correction factor). However, it should not be used interchangeably with specular microscopy as a tool for the measurement of corneal thickness.
Keywords: imaging/image analysis: clinical • topography • anterior segment