Comparability Test between Time Domain Optical Coherence Tomography (TD-OCT) and Multiple Spectral Domain OCT (SD-OCT) Devices

Abstract

Purpose: : We have developed a novel method that successfully identifies TD-OCT (Stratus OCT; Carl Zeiss Meditec, Inc., Dublin, CA (CZMI)) circle scan locations within spatially isotropic (evenly sized and spaced) three-dimensional (3D) SD-OCT scan volumes. The purpose of this study was to compare the performance of our method on SD-OCT devices that provides spatially isotropic and anisotropic volumes.

Methods: : Twelve healthy subjects (12 eyes) had 1 central and 8 displaced peripapillary TD-OCT circle scans. The same eyes had ONH centered 3D cube scans with SD-OCT devices: Cirrus HD-OCT (spatially isotropic, 200x200 samplings in 6x6 mm; CZMI), RTVue (spatially anisotropic, 513x101 samplings in 4x4 mm; Optovue, Fremont, CA), and Spectralis (spatially anisotropic, 512x193 samplings in 6x6 mm; Heidelberg Engineering, Heidelberg, Germany). The analogous circle location of the TD-OCT was detected within the SD-OCT volume scan using software of our own design. Mixed effect models were used to estimate the distance between the TD-OCT Circle scan center and corresponding SD-OCT matched scan center. A subset analysis was performed using only scans where the entire TD-OCT scanning circle was within 4x4 mm scanning window (41 scans).

Results: : The differences [95% confidence interval] in the center location of the scanned circle between TD-OCT and Cirrus, RTVue, and Spectralis were 87.28 [65.04-109.53] µm, 246.87 [207.00-286.74] µm, and 97.58 [71.85-123.31] µm, respectively. The difference was not statistically significantly different between Cirrus and Spectralis, but RTVue showed statistically significantly larger differences in comparison to both Cirrus and Spectralis. The subset analysis showed similar results.

Conclusions: : Our backward comparability technique is robust for SD-OCT comparison of TD-OCT scans across different scan design.

Keywords: imaging/image analysis: clinical