Microvasculature Imaging by Wide Field Dual-Beam Optical Coherence Angiography

Abstract

 

Purpose

 

Noninvasive three-dimensional retinal micro-vasculature imaging will be a suitable disease diagnosis tool that will detect layer-discriminated alterations and can be used as periodic monitoring. This paper demonstrates wide field-of-view (FOV), non-invasive, three-dimensional microvasculature imaging of human eyes by dual-beam optical coherence angiography (DB-OCA).

 

Methods

 

Single eye of 1 subject (26 yo, male) without any abnormalities and 1 eye of 1 subject (70 yo, male) diagnosed as polypoidal choroidal vasculopathy (PCV) were examined by DB-OCA. High-sensitivity and high-speed blood flow detection in micro-vessels was performed by high-speed spectral-domain OCT with dual probing beams at 840 nm wavelength. The two probing beams scan the same location on the retina with long time delay, and the displacement due to slow blood flow in micro-vessels is detected. This system is operated at 123,000 axial scans per second per each beam. Three-dimensional blood flow distributions were acquired. Depth-resolved vasculature images were provided from these distributions. For wide field imaging, several different locations of the posterior part of the eye have been scanned up to 40 × 40° and mosaics of DB-OCA images are provided to visualize microvasculature in wide field.

 

Results

 

In 1 eye without abnormalities, about 27 × 40° of FOV is covered by the mosaic of vasculature image. Complex retinal capillary bed around the fovea and radial capillary pattern in the retinal nerve fiber layer around the optic nerve head were observed. In 1 eye of PCV patient, mosaic of vasculature was obtained, which covers about 27 × 32° of FOV (Fig. 1). Abnormal blood flow signals were observed at some part of the retinal pigment epithelium (RPE) detachment. They were located between the RPE and the Bruch’s membrane. Micro-vessels of abnormal vascular network are clearly visualized.

 

Conclusions

 

Wide-field DB-OCA visualizes three-dimensional microvasculature non-invasively with FOV comparable to those of standard posterior imaging instruments. Non-invasive three-dimensional microvasculature angiography will be suitable for monitoring and/or screening retinal vascular diseases.

 

 

The posterior part imaging of a PCV patient. (a) The fundus photograph, (b) mosaic of ICGA, (c) mosaic of DB-OCA, and (d) a part of mosaic of DB-OCA at the yellow box (13.3 × 13.3°).

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 436 blood supply • 688 retina