Correlation of macula thickness parameters in healthy subjects acquired using SDOCT structural-only and angiography all-in-one scans

Abstract

Purpose : With the introduction of optical coherence tomography angiography (OCTA) in clinical OCT devices, one must acquire two separate scans (structural OCT and OCTA) in order to access both the wealth of angiography information and structural metrics such as macula thickness. This is also required to be able to compare the macula thickness parameters with prior scans of the same eye. The purpose of this study is to demonstrate that an all-in-one OCTA scan can provide comparable structural metrics to those acquired using the structural-only scan.

Methods : In this study we designed and implemented a prototype all-in-one OCTA 6x6 mm scan (490 A-scans/B-scan, 490 B-scans, 2 repetitions) in CIRRUS^TM 6000 AngioPlex (ZEISS, Dublin, CA). B-scans acquired using this prototype OCTA scan were down-sampled to 200x200 A-scans per cube using nearest neighbor interpolation method, in order to compare with structural B-scans acquired using Macula Cube 200x200.
Ten healthy subjects (N=10) were scanned using the prototype scan and Macula Cube 200x200 under an IRB-approved study. The macula thickness analysis was applied on both datasets and the resultant values were compared using Bland-Altman plots.

Results : Figure 1 shows examples of angiography en face, structural en face, and OCT B-scans acquired using these two scan types. The all-in-one OCTA 6x6mm scan provides superior angiography en face and OCT B-scan image quality compared with Macula Cube 200x200 scan. Figure 2 shows the Bland-Altman plots for four inner quadrants (superior, nasal, inferior, temporal) and the central region of the ETDRS grid. The analysis shows good correlation (r²>0.92) and low coefficient of variance (CV<1.3%) in all regions.

Conclusions : Our results demonstrate good correlation between macula thickness parameters acquired using a structural OCT scan and an all-in-one OCTA scan. This finding can potentially eliminate the need for acquiring multiple OCT/A scans in order to obtain both angiography and structural metrics, while maintaining data equivalency with prior scans of the same eye.

This is a 2021 ARVO Annual Meeting abstract.

 

Figure 1: Examples of all-in-one OCT Angiography 6x6 mm scan and Structural OCT 6x6 mm scan.

 

Figure 2: Bland-Altman plots for macula thickness in inner superior, nasal, temporal, and inferior quadrants as well as the central region. Meas. A: Structural OCT 6x6 mm scan; Meas. B: All-in-one OCT Angiography 6x6 mm scan.