Visual impairment of ischemic central retinal vein obstruction (CRVO) is sudden and severe.

Large areas of capillary non-perfusion (NPA) are often associated with risk of neovascularization.
Fluorescein Angiography (FA) is commonly used to monitor the development of NPA. But traditional FA is still not large enough to cover peripheral and posterior pole to visualize capillary nonperfusion in these areas, unless montage is utilized from multiple-position acquisitions. OCT Angiography (OCTA) is new developed technology with many advantages over FA. Non-invasive, high resolution, capability of segmentation, etc. However, scan area of most current OCTA is even smaller than FA, which becomes the biggest limitation of extensive application of OCTA, until……
TowardPi introduce 400KHz speed SS-OCT/OCTA covering 120° fundus with just one capture in only 15 seconds. From this case (Fig1), in addition to the severe capillary flow drop-out in peripheral and posterior, tortuosity and engorgement of all branches of the central retinal vein can be seen clearly as well.

Fig2 is choroid Sattler’s and Haller’s layers vessels, reconstructed by TowardPi’s new algorithm, one more breakthrough of OCTA technology. It demonstrated an independent circulation system of choroid, in spite of severe ischemic change in retina.

Powered by extremely fast speed (400,000 A-scan/sec) and optimized interval. Theoretically detection threshold of blood flow velocity is 30um/s (Fig3). Which is 167 times slower than bottom limit of healthy human eyes (around 5mm/s).

“Ultra-wide-angle OCTA images show the strong independent R&D capability of TowardPi technical team. It has an epochal significance in rewriting the existing clinical diagnosis procedure of retinal vascular diseases!” Images courtesy and endorsement by author: Prof. Lijun Shen, Zhejiang Provincial People's Hospital, Hangzhou, China

Editor: Dr. Jian Zhou (TowardPi Medical)