102. Orbital Vascular Variations in a Rabbit Model of Retinoblastoma Treatment

Authors: Michael Joseph Feldman, MD

Retinoblastoma (RB) is the most common ocular malignancy in children. Neuroendovascular approaches to chemotherapy administration have revolutionized the RB treatment paradigm. The New Zealand White rabbit (NZWR) was developed as a small-animal experimental model of intra-arterial chemotherapy (IAC) for retinoblastoma treatment. The NZWR has dual ophthalmic arteries (OA): the external OA (EOA) arises from the external carotid artery and the internal OA (IOA) from the internal carotid artery. We describe the technique that we have refined for OA catheterization in rabbits, and describe the angiographic variations in the NZWR OA supply and potential implications for IAC delivery in children.Methods: We developed a novel technique to perform angiography of the external and internal carotid arteries and superselective angiography of the EOA and IOA in NZWR using transfemoral access and a microwire/microcatheter system that mimics our human IAC paradigm. IOA and EOA dominance was angiographically determined prior to selective OA catheterization.
114 NSWRs underwent successful carotid angiographic evaluation and OA catheterization (161 total eyes evaluated, 112 right, 49 left). EOA was dominant in 73% (118/161), and IOA was dominant in 17% (27/161). Co-dominance was seen in 10% (16/161). Of the rabbits with bilateral OA catheterization, 25/47 (53%) had bilaterally dominant EOA.
Successful catheterization of the OA in the NZWR can be accomplished with nuanced technique mimicking that used in humans. The external OA is the dominant arterial supply in the majority of NZWR eyes. These findings allow for successful reproduction of OA catheterization studies of IAC for retinoblastoma in NZWR. These findings also give insight into the utility of various ICA and ECA directed IAC techniques in humans. Importantly, NZWR OA catheterization offers the potential for improved experience in an infrequently performed and high-risk endovascular technique. This model also will allow for refinement of chemotherapeutic cocktails and administration in RB.