Purpose:
Chorio-capillaries (CCs), pre-capillary arteries and post-capillary venules have a dense and complex three-dimensional structures. We propose adaptive optics optical coherence angiography (AO-OCA) which enables high-resolution and volumetric imaging. This paper is aims at demonstrating high-resolution in vivo chorio-capillaries imaging by AO-OCA.
Methods:
Three eyes of 3 healthy subjects were involved in this study. The eyes were scanned by a custom built AO-OCA. AO-OCA is a Doppler optical coherence tomography (OCT) equipped with adaptive optics. Owing to the OCT detection and adaptive optics, it provides a cellular level three-dimensional retinal tomography. At the same time, owing to the Doppler function, the Doppler OCT is capable to visualize microscopic vasculature three-dimensionally. Volumetric measurements were performed for the subjects with a scanning size of 0.8 deg x 0.8 deg at a speed of 5.6 volumes/s, and 9 sequential volumes were obtained in a single session. High-sensitive Doppler volumes were obtained by inter-B-scan Doppler processing. The CCs were segmented with an approximately 15 μm thickness beneath the retinal pigment epithelium (RPE). In addition, 137 sessions were performed for one eye and a large field of view mosaic was created.
Results:
Strong Doppler signals were observed at very thin layer beneath the RPE for all eyes in the B-scan images. This may indicate blood flow in CCs. By comparing en-face projections of the CCs between intensity OCT and Doppler tomography, it was found that the Doppler tomography detects particular capillaries or capillary-like patterns but not in the intensity images for all eyes, as shown in Figs. (a) and (b). The large field image also showed strong Doppler signals at CCs in the B-scan images and characteristic patterns in en-face Doppler images, as shown in Figs. (c) and (d).
Conclusions:
Doppler AO-OCA was found to be capable to visualize CCs structures. This system could be useful for in vivo and non-invasive micro angiography of posterior eye.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • choroid • blood supply