Optimizing procedures for ocular radiation injury studies in the tree shrew

Radiation exposure to the eye during cancer treatment can lead to ocular radiation injury (ORI), a devastating condition that can have a profound and permanent impact on vision-related quality of life. Rodent models do not have adequate ocular anatomy to accurately simulate human ORI, and modeling in non-human primates is limited by logistical and ethical concerns. To improve future translational research investigating ways to treat or prevent ORI, we developed protocols for a tree shrew model of ORI. Northern tree shrews (Tupaia belangeri) were obtained by our laboratory. Custom housing and handling methods were developed, including custom body suits to maintain the tree shrew's body temperature during procedures. Radiation delivery was optimized to accurately deliver radiation, and imaging was performed to observe fundus changes from ORI. Optimization of tree shrew handling, housing, anesthesia approaches, radiation delivery, and clinically-relevant ocular imaging permitted successful induction and assessment of ORI in tree shrews. With these protocols, tree shrews can be used as a highly relevant model organism with key anatomic features similar to humans to study ORI.