Abstract
Purpose :
To evaluate the agreement between different commercially available instruments and UltraSound Pachymetry(USP) on measurements of Central Corneal Thickness (CCT).
Methods :
An observational, cross-sectional study. Two-hundred and eighteen eyes of 109 healthy patients were enrolled, and sequentially examined by means of USP, Swept-Source Optical Coherence Tomography (SS-OCT Casia), Spectral-Domain Optical Coherence Tomography (SD-OCT Optovue), Non-Contact Specular Microscopy (NCSM) and Rotating Scheimpflug Camera (RSC). The sequence of examination was randomized, except for USP, the last to be performed. With each instrument, the same examiner acquired 3 consecutive CCT measurements per eye, and the average value was used for the analysis. Linear correlations between CCT values acquired with different instruments and USP were computed, to test the strength of measurement associations. Bland-Altman plots were drawn to describe measurement agreement between optical instruments and USP.
Results :
Mean CCT values (±SD) were 549.82 ± 29.95, 552.34 ± 27.74, 538.28 ± 26.88, 525.18 ± 29.02, and 563.58 ± 52.73 μm, respectively for USP, RSC, SS-OCT Casia, SD-OCT Optovue and NCSM. Figure 1 shows the correlation coefficients (r) of SS-OCT Casia, SD-OCT Optovue, RSC, NCSM vs. UPS were 0.914, 0.882, 0.902 and 0.398, respectively (p<0.001 for all the correlations). When evaluating the Bland-Altman plots, as illustrated in Figure 2, SD-OCT Optovue showed the highest mean difference of CCT measurements against USP (+24.63 µm), while the lowest mean difference was achieved by RSC (-2.53 µm). Intermediate values were obtained by NCSM and SS-OCT Casia (-13.77, +11.54 µm respectively).
Conclusions :
The results support the use of optical methods as a viable alternative to USP pachymetry. Of the tested instruments, RSC proved as the best alternative to USP, with a strong correlation of measurements (r=0.902) and a good agreement (mean difference with USP: -2.53 µm). Furthermore, SS-OCT Casia showed a good correlation with the USP gold standard.
This is a 2021 ARVO Annual Meeting abstract.