Purpose
To demonstrate that the new Cirrus-5000 Angio-prototype is capable to achieve both quantitative and qualitative evaluations of retinal vasculature features for human subjects with Diabetic Retinopathy.
Methods
A Cirrus-5000 instrument was modified to allow OCT angiography imaging. The system could provide two scanning modes for imaging ocular vasculature, a 6 mm x 6 mm with 350 by 350 A-scans and a 3 mm x 3 mm scan with 245 by 245 A-scans to achieve higher resolution. Both scanning modes could be finished ~ 4 seconds. The microvasculature data obtained from OCT intensity cube were segmented into three layers (superficial, deeper and outer retinal layers) and color encoded into different colors (red, green and blue respectively). The color composite image could be used to indicate the relative depth positions of vasculature features.<br /> A DR subject and a normal subject were recruited and imaged. Fluorescein angiography imaging and OCT angiography imaging were both performed on the DR subject, and the normal was imaged only with OCTA. Visual comparison was performed between the FA and OCTA images and features of interest were correlated. A vessel density calculation method was applied on both DR and normal OCT angiography images.
Results
OCT angiography revealed much clearer microvascular details compared to the FA image. Many vasculature features were well observed in the OCT angiography image. Microaneurysm, capillary drop out and capillary tortuosity could be detected through OCT angiography without using imaging dye. Unlike FA images, the OCT angiography image provided depth resolved information.<br /> The vessel density results of normal and DR subjects clearly demonstrate that the vessel density of DR subject is lower than normal subject, which is primarily due the capillary drop out of DR subject.
Conclusions
The Cirrus-5000 Angio-prototype is capable of achieving non-invasive detailed depth resolved microvasculature map for DR retinal vasculature evaluation. The images delivered by Cirrus-5000 Angio-prototype have good correlation with FA images, quantitative analysis is also possible.