Purpose: To investigate the feasibility of using spectral domain optical coherence tomography (SD-OCT), infra-red and multicolor fundus imaging for monitoring the safety and efficacy of therapeutics delivery into the extravascular spaces of the choroid (EVSC).
Methods: Two hundred and fifty microliters containing Indocyanine Green (ICG), sodium fluorescein, iron oxide nanoparticles (IONPs) or 15 million human bone marrow stromal cells (hBMSCs) were injected using a novel minimally-invasive adjustable-depth blunt injector into the EVSC of New Zealand White rabbits, 3.5 mm posterior to the limbus. SD-OCT, infra-red and multicolor fundus imaging and histology analysis were performed to assess injection safety and efficacy.
Results: Infra-red wide angle (102°) imaging demonstrated that injected therapeutics covered over 80% of the posterior eye surface across the EVSC. Multicolor imaging demonstrated that injected dyes were localized in the matrix between the choroidal blood vessels. SD-OCT analysis revealed no retinal detachment, choroidal hemorrhages or inflammation up to 10 week following cell transplantation. These findings were supported by histology analysis.
Conclusions: Multimodal imaging including infra-red and multicolor fundus imaging as well as SD-OCT enables longitudinal monitoring of safety and efficacy of therapeutics delivery into the EVSC. Moreover, these imaging techniques enable to quantitatively determine the distribution of injected therapeutics in the EVSC.
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