Retinochoroidal Blood Flow is Demonstrated in an Orthotopic Vascularized Whole Eye Transplant Model

Abstract

Purpose : Approximately 39 million people worldwide are blind. Whole eye transplantation (WET) could potentially provide a viable optical system to patients with irreversible vision loss. We have developed an orthotopic model for whole eye transplantation in the rat. Previous doppler optical coherence tomography and gadolinium enhanced magnetic resonance imaging studies have suggested that retinal blood flow can be established after WET. Given that the viability of the retina is crucial to functional visual return, we sought to investigate the structural integrity of the retinal and choroidal vasculature after WET with fluorescein angiography (FA).

Methods : Exams under anesthesia (EUAs) and color fundus and fluorescein angiography (FA) imaging were performed in right eyes of 7 Brown Norway rats prior to transplantation. These eyes served as controls (n=7). The eyes were orthotopically transplanted to Brown Norway recipients (n=7) and transplanted and contralateral eyes underwent the same testing at 1 and 3 weeks after WET. Ophthalmologists with retina specialization performed EUAs, evaluated images and documented retinochoroidal findings.

Results : FA imaging revealed that all transplanted eyes exhibited complete arterial, venous and choroidal filling at 1 week after WET. Imaging of 4 of 7 transplanted eyes at 3 weeks postoperatively confirmed complete filling of retinochoroidal vasculature; the remaining 3 transplanted eyes had corneal opacities that prohibited imaging. There was no leakage in the retinal vasculature in the transplanted eyes at 1 and 3 weeks after WET. Mild focal choroidal hyperfluorescence was noted in transplanted eyes of 3 of 7 animals, with improvement in one of these eyes by week 3. 5 of 7 transplanted eyes exhibited mild to moderate retinal vessel narrowing in both color fundus and FA images. No abnormal optic disc hyperfluorescence was seen in the transplanted eyes at either time point.

Conclusions : FA results have confirmed retinochoroidal blood flow in a rat model of WET. In all transplanted eyes, complete vascular filling and an absence of retinal vessel leakage were noted, the latter indicating that the structural integrity of inner blood retinal barrier can be maintained after WET. The mild choroidal hyperfluorescence and the vascular attenuation observed in this study will be investigated in future studies.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.