Purpose
Anti-VEGEF is an effective treatment of exudative macular diseases. However, it requires repeated injections and hence, also frequent fluorescein angiography (FA) or indocyanine green angiography (ICGA) imaging. Since FA and ICGA are invasive, a non-invasive alternative is great interest. This paper demonstrates a new imaging modality, multi-contrast OCT (MC-OCT) for noninvasive monitoring of the exudative macular diseases.
Methods
Two eyes of age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) were involved. Intravitreal ranibizumab injection (IVR) was performed 3 times (AMD) and 1 time (PCV). MC-OCT was performed after the 1st and the 3rd IVR (AMD) and after the 1st IVR (PCV). Color fundus, FA, ICGA, and fundus auto-fluorescence were also performed. The MC-OCT is a custom-build system with 1.06 μm probe wavelength. It has a high-penetration to the choroid with a depth resolution of 6.2 μm. A high-measurement speed of 100,000 A-lines/s enables high-dense volumetric scan for 6.6 s with a 6.0 mm × 6.0 mm area. By a single scan, 3-D tomographies of conventional OCT, power Doppler OCT, and degree-of-polarization-uniformity (DOPU) are obtained. The power Doppler OCT provides non-invasive 3-D angiographies. DOPU is known to be low at the retinal pigment epithelium (RPE), so it provides specific contrast to RPE.
Results
For the AMD case, power Doppler OCT visualized abnormal flow at the pathologic region before the 2nd IVR. The abnormal Doppler flow was reduced after two times of IVR. En face projection of the power Doppler OCT and mid-phase ICGAs showed high similarity. Low DOPU cluster was found at the pathologic region before the 2nd IVR, it would a segmented RPE. This segmented RPE still existed after the 3rd IVR despite of the restoration of structural abnormality. In the PCV case (Figure), clear abnormal Doppler flow was observed beneath the RPE detachment before IVR. This Doppler signal corresponded to abnormal vessels appeared in ICGA. Both of the abnormal Doppler flow and abnormal vessels in ICGA were reduced after IVR. In the pathologic region, DOPU showed partial absence of PRE, which was collocated with FA leakage.
Conclusions
The Doppler flow image and RPE contrast well corresponded to ICGA and FA. MC-OCT is expected to be utilized for the optimization of IVR.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
550 imaging/image analysis: clinical •
412 age-related macular degeneration