Abstract
Purpose :
The ability to compare retinal and nerve fiber layer thickness measurements (TM) over multiple imaging sessions and to evaluate disease progression in glaucoma over time is of importance for disease management. As optical coherence tomography (OCT) systems advance the acquisition speed, it is crucial to understand how measurements acquired using multiple generations of OCT may be compared. The purpose of this study is to investigate the clinical data equivalency between two spectral domain OCT systems, operating at 27kHz and 100kHz axial scan rates in a normal population.
Methods :
In order to compare the image quality, we initially performed a benchtop study using phantom test eyes, five CIRRUSTM 6000 (ZEISS, Dublin, CA), and six CIRRUSTM HD-OCT 5000 (ZEISS, Dublin, CA) devices. The test eye was designed to mimic the human retina layers. The image background noise (BN) and layer brightness (LB) of scans were compared. Furthermore, normal subjects (N=15) were enrolled in this study to clinically evaluate TM. One eye per subject was scanned using two Macular Cube 512x128 and two Optic Disc Cube 200x200 scans on two CIRRUS 5000 and three CIRRUS 6000 devices. Acquired datasets were then analyzed using the native analysis software and a total of 31 TM parameters of retina and nerve fiber layer were evaluated.
Results :
In the phantom study, we observed that BN and LB of all CIRRUS 6000 devices fall within those of CIRRUS 5000 devices. In the clinical study, the mean differences for all TM were found to be small with the largest difference of 4.3 micron (see Figure 1). The 90 percent confidence intervals of the mean differences are within the pre-established limits. Clinical data equivalency is further demonstrated by deming regression analysis and high R2 values (>0.923) (see Figure 1 / 2a). We found a strong correlation between both groups of devices in the Bland-Altman plots (see Figure 2b).
Conclusions :
Our findings demonstrated that images acquired on both devices were considered equivalent despite the differences in acquisition speed. The image quality metrics such as LB, BN and TM were found to be equivalent within the pre-established limits.
This is a 2020 ARVO Annual Meeting abstract.