Purpose:
Optical microangiography (OMAG) is a recently developed 3D non-invasive imaging technique capable of providing detailed microvasculature map at capillary level resolution within the scanned tissue volume, up to an imaging depth of ~2 mm. OMAG is a variation of optical coherence tomography. This study aims to demonstrate the utility of OMAG in imaging capillary level microvasculatural network within retina and choroid.
Methods:
A custom-built OMAG system was used to image 5 eyes of 5 normal subjects. The system was running at 850 nm central wavelength (SLD), 140,000 axial scan per second. The scan protocol was 4 x 4 mm square containing 512 x 512 A-scans. The total imaging time for a 3D imaging of 4x4 mm2 area on the retina was ~2 s. The data processing was performed off line, which provided in parallel the conventional volumetric OCT microstructure image and microcirculation image for retina and choroid. From microstructural image, the retinal and choroidal thickness was measured at para- and peri- fovea region. The microcirculation image was used to visualize/measure the density of capillary vessels.
Results:
Detailed/dense microvasculature network was observed for all 5 eyes. And its appearance was similar among the subjects, and correlated well with the descriptions found in the standard textbook. Because of depth-resolved imaging capability, OMAG can optically slice the microvasculature network at different landmarked layers within retina and choroid (see Figure).
Conclusions:
The capability of OMAG to image the microvasculature network is superior to any other non-invasive imaging technique. The demonstrated results promise the future clinical applications for IMAG in ophthalmology.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • neovascularization