Longer Interscan Times in OCT Angiography Detect Slower Capillary Flow in Diabetic Retinopathy

Yoshihiro Kaizu; Shintaro Nakao; Tomomi Soda; Juun Horie; Iori Wada; Muneo Yamaguchi; Atsunobu Takeda; Koh-Hei Sonoda

doi:10.1016/j.xops.2022.100181

Longer Interscan Times in OCT Angiography Detect Slower Capillary Flow in Diabetic Retinopathy

Ophthalmol Sci. 2022 Jun 13;2(3):100181. doi: 10.1016/j.xops.2022.100181. eCollection 2022 Sep.

Authors

Yoshihiro Kaizu¹, Shintaro Nakao^{1

2

3}, Tomomi Soda^{2

3}, Juun Horie⁴, Iori Wada¹, Muneo Yamaguchi¹, Atsunobu Takeda¹, Koh-Hei Sonoda¹

Affiliations

¹ Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
² Department of Ophthalmology, National Hospital Organization, Kyushu Medical Center, Fukuoka, Japan.
³ Clinical Research Institute, National Hospital Organization, Kyushu Medical Center, Fukuoka, Japan.
⁴ Canon Inc., Tokyo, Japan.

Abstract

Purpose: To investigate the detection of slower retinal capillary blood flow using commercial OCT angiography (OCTA) with a longer interscan time in diabetic retinopathy (DR).

Design: Observational, prospective, cross-sectional study.

Participants: A total of 62 eyes from 39 subjects with diabetes mellitus and 10 eyes from 9 healthy subjects.

Methods: Commercial spectral domain-OCT was used to obtain 3 × 3-mm fovea-centered OCTA images of all eyes with 3 different interscan times (4.3, 5.7, and 8.6 ms). For each interscan time, OCTA imaging was performed 5 consecutive times, and a ×5 averaged image was obtained. Capillary flow density and visualization of retinal capillaries in the superficial and deep capillary plexuses (SCPs and DCPs, respectively) were compared between the 3 averaged images from the 3 different interscan times.

Main outcome measures: Capillary flow density and visualization of foveal capillaries in 3 images with different interscan times.

Results: Forty-five eyes of 34 patients were analyzed. There was no significant difference in the flow density of the SCP and DCP between the 3 images with different interscan times in all the DR stages. Some capillaries including microaneurysms that could not be observed at 4.3 ms could be observed at 5.7 or 8.6 ms. There were significantly more capillaries with difference points between the 3 images in the group with DR than in the group without DR (P < 0.01). The morphology of some microaneurysms also changed with longer interscan times.

Conclusions: OCTA with longer interscan times revealed slower flow points in capillaries and more accurate visualization and morphology of microaneurysms in DR.

Keywords: AOSLO, adaptive optics scanning laser ophthalmoscopy; Capillary dropout; DCP, deep capillary plexuses; DME, diabetic macular edema; DR, diabetic retinopathy; Diabetic macular edema; FA, fluorescein angiography; FAZ, foveal avascular zone; GA, geographic atrophy; IPL, inner plexiform layer; Microaneurysms; NDR, no DR; NPDR, nonproliferative DR; OCTA, optical coherence tomography angiography; PDR, proliferative DR; SCP, superficial capillary plexuses; SD-OCT, spectral domain optical coherence tomography; VISTA; VISTA, variable interscan time.