Abstract
Purpose :
In healthy eyes, variations of intraocular pressure (IOP) are regulated by a careful balancing of aqueous production and drainage; the dynamics of which have been extensively studied using anterior segment perfusion models. However, to the best of our knowledge, no reports have assessed retinal viability within these systems. In this study, we established a whole globe perfusion system which maintains constant IOP and fluid convection in porcine and human eyes in order to assess retinal cell morphology and survival for upwards of 48 hours.
Methods :
Physiological regulation is mimicked by monitoring IOP, and adjusting the infusion rate of surrogate aqueous and culture medium in order to maintain a pre-set IOP value. Physiological temperature and pH are also maintained. Ocular integrity was monitored by continuous measurement of fluid infusion rate, pressure, and outflow facility. Retinal tissue viability was assessed using cell-specific markers and TUNEL staining via confocal microscopy.
Results :
The system maintained a constant pressure of 18 mmHg in both porcine and human eyes for upwards of 48 hours, under physiologically relevant infusion rates between 1-5 µL/min. Confocal microscopy indicated that retinal tissue markers of perfused eyes remain detectable in both species. Furthermore, non-perfused human and pig eyes exhibited a dramatically disrupted morphology compared to perfused samples and positive controls. At 48 hours, perfused pig eyes demonstrated significantly reduced apoptosis compared to unperfused eyes in the GCL (40.17 ± 5.32 vs. 62.75 ± 16.72 cells/mm, p < 0.001), INL (69.50 ± 4.02 vs. 119.17 ± 1.97 cells/mm, p < 0.001), and the ONL (41.58 ± 2.07 vs. 59.58 ± 2.17 cells/mm, p < 0.002).
Conclusions :
Our perfusion system shows promise as a whole eye organotypic model to study retinal cell interactions under physiological and pathological pressure dynamics. Furthermore, as physiological convectional fluid flow is established, our system may be useful as a tool to address intraocular drug distribution.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.