Abstract
Purpose :
To compare foveal avascular zone (FAZ) area measurements produced by different optical coherence tomography angiography (OCTA) devices when imaging normal eyes.
Methods :
All eyes in this cross-sectional study underwent OCTA using two different OCTA devices: Spectralis HRA+OCTA (Heidelberg Engineering) and Nidek RS-3000 Advance device (Nidek, Gamagori, Japan). Using OCT en face angiograms, automatically segmented into the superficial retinal capillary plexus (SCP) and the deep retinal capillary plexus (DCP), two graders manually measured the FAZ area.
Results :
A total of 59 normal eyes from 33 subjects were included (17 males, 16 females; mean 26 ± 3 years of age).
Mean FAZ areas were 0.327 ± 0.091 mm2 at the SCP and 0.568 ± 0.173 mm2 at the DCP measured at Nidek RS 3000, 0.299 ± 0.085 mm2 at the SCP and 0.349 ± 0.079 mm2 at the DCP measured at Spectralis. The two devices’ measures were significantly different both at the SCP and at the DCP (p< 0.0001, for both).
The intra-operator agreement was excellent with both devices at the SCP [ICC= 0.96 (95% CI: 0.93 to 0.98) with Nidek RS-3000 and 0.97 (95% CI: 0.93 to 0.98) with Spectralis]. At the DCP, it was good with Spectralis [ICC: 0.85 (95% CI: 0.62 to 0.93), fair with Nidek RS-3000 [ICC= 0.64 (95% CI: 0.33 to 0.81)].
The inter-operator agreement was excellent for Spectralis [ICC= 0.97 (95% CI: 0.93 to 0.98), good for Nidek RS-3000 [ICC= 0.93 (95% CI: 0.57 to 0.98) at the SCP. It was good at the DCP with both devices [ICC: 0.74 (95% CI: 0.52 to 0.87) with Nidek RS3000; and 0.81 (95% CI: 0.63 to 0.91) with Spectralis].
Conclusions :
OCTA is a reliable method for the quantification of FAZ area, particularly when measured in the SCP. However, FAZ area measurements obtained with different OCTA devices are different. These differences appear to be primarily attributable to the analysis algorithms used to set SCP and DCP. These findings should be taken in consideration when planning a follow-up of patients with retinal vascular diseases that affect capillary plexuses.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.