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Retinal neovascularization is a major cause of vision loss and blindness, and is a common complication of numerous retinal diseases, including proliferative diabetic retinopathy, retinopathy of prematurity, sickle cell retinopathy, and retinal vein occlusions. Early diagnosis can be highly beneficial to the treatment of angiogenesis-related eye diseases. Due the limitations of current ocular imaging methods, a hybrid imaging approach that can combine the advantages of current imaging technologies with additional functional and molecular information is highly desired in the field of ophthalmology. A multimodality imaging system with integrated optical coherence tomography (OCT), photoacoustic microscopy (PAM), and fluorescence microscopy (FM) has been developed to evaluate the angiogenesis in clinically relevant larger animal eyes. Real-time, high resolution in vivo imaging was performed in live rabbit eyes with vascular endothelial growth factor (VEGF)-induced retinal neovascularization. PAM images demonstrate a network of tortuous neovascularization on the retina peaking at 7 days post-injection. Blood vessels and irregular vascular structures can also be indicated by OCT B-mode imaging. Leakage of retinal neovascularization is demonstrated by fluorescein sodium with FM. Quantitative analysis of retinal neovascularization has been achieved by PAM. The experimental results demonstrate that this multimodality imaging system can noninvasively visualize retinal neovascularization in both albino and pigmented rabbits for characterization of retinal pathology. This work presents the first description of a multimodality PAM, OCT, and FM system for high resolution, real-time visualization of angiogenesis in rabbits, and could be an important step toward the clinical translation of the technology.
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