Purpose
In-vivo assessment of choroidal neovascularization (CNV) is currently done via optical coherence tomography (OCT) and fluorescein/ICG angiography, and recently, the novel technology of OCT angiography (OCT-ang) - a system capable of measuring retinal blood flow. The purpose of this study is to explore whether OCT-ang accurately correlates with histological neovascularization in an experimental model of murine laser induced CNV.
Methods
Twenty adult pigmented mice of mixed background were anesthetized and subjected to laser induced CNV following pre-established protocols. Four laser lesions were applied around the optic nerve to induce rupture Bruch's membrane; laser applications that did not result in a bubble formation indicating rupture of Bruch’s membrane were excluded from analysis. Animals were imaged with OCT-ang at varying intervals between 1 to 28 days post laser injury in order to visualize the development & regression of CNV. Histological samples were obtained at the corresponding intervals - eyes were paraformaldehyde-fixed and stored in phosphate buffered saline at 4oC. The choroid was dissected, stained with isolectin B4 and flat mounted to visualize the CNV. These images were compared to OCT-ang images obtained the same day.
Results
Comparing the images obtained from OCT-ang to the immunostained flat mount shows consistency between the two modalities. The vessels visualized by the OCT-ang are representative of the vessels visualized via immunostaining of the choroidal flat mount (see figure). We observed that the OCT-ang images have better contrast between background and neovascular images. Further analysis of the various time points is underway to identify the earliest detectable lesion on OCT-ang.
Conclusions
OCT angiography of CNV correlates well with the true choroidal morphology as viewed in choroidal vascular flat mount. Since the murine laser induced CNV model is a widely accepted model for human neovascular AMD, this technology holds promise for in vivo detection & management for neovascular AMD.