Reliability of Entire Corneal Thickness Mapping in Normal Post-Laser in situ Keratomileusis and Keratoconus Eyes Using Long Scan Depth Spectral Domain Optical Coherence Tomography.

PURPOSE

To investigate the repeatability and reproducibility of mapping the entire corneal thickness using spectral domain optical coherence tomography (SD-OCT).

METHODS

Thirty normal eyes, 30 post-laser in situ keratomileusis (LASIK) surgery eyes, and 30 keratoconus eyes were analyzed. A custom-built long scan depth SD-OCT device was used to obtain entire corneal images. Ten-millimeter-diameter corneal thickness maps were generated by an automated segmentation algorithm. Intraclass correlation coefficients of repeatability (ICC1) and reproducibility (ICC2), and coefficients of repeatability (CoR1) and reproducibility (CoR2), were calculated to quantify the precision and accuracy of corneal pachymetry measurements using the Bland-Altman method.

RESULTS

For SD-OCT measurements in healthy subjects, CoR1 and CoR2 were less than 5.00 and 5.53 μm. ICC1 and ICC2 were more than 0.997 and 0.996. For SD-OCT measurements in LASIK patients, CoR1 and CoR2 were less than 5.09 and 5.34 μm. ICC1 and ICC2 were more than 0.997 and 0.996. For SD-OCT measurements in keratoconus patients, CoR1 and CoR2 were less than 11.57 and 10.92 μm. ICC1 and ICC2 were more than 0.995 and 0.996.

CONCLUSIONS

The measurements of corneal pachymetric mapping by long scan depth SD-OCT can be assessed over the entire corneal area with good repeatability and reproducibility.