Abstract
Purpose :
Separation of photoreceptors from underlying retinal pigment epithelium, as occurs during retinal detachment (RD), causes photoreceptor cell death and vision impairment. While rodent and rabbit models of RD recapitulate aspects of the pathogenesis of human RD, the closer anatomic and physiological homology of nonhuman primates presents a potentially more translational model in which to evaluate novel therapies. In this study, anatomic and functional features of RD induced by subretinal delivery of viscoelastics were assessed in a primate model of sustained RD.
Methods :
Eyes of adult African green monkeys (Chlorocebus sabaeus, St. Kitts origin) received subretinal injections of either saline (n=3), sodium hyaluronate (n=6) or hydroxypropyl methylcellulose (n=3). Ophthalmic data were collected from baseline to Day 28 to assess the area of the detached retina by fundus images, retinal volume and thickness by OCT and electrophysiology recordings to study functional and physiological changes by multi-focal ERG (mfERG) and biomarker analyses.
Results :
Upon injection in the subretinal space, the viscoelastics induced retinal detachment and formation of an elevated circular bleb proportionate to injected volume. Over the course of two weeks, this was accompanied by increases in retinal volume and thickness in the bleb region in all three groups. Ophthalmoscopy and OCT revealed transient retinal detachment following subretinal saline delivery and a more sustained detachment following viscoelastic injection. At study terminus on Day 28, the bleb area had diminished to ~50% in many viscoelastic injected eyes, whereas the retinas had completely reattached in saline injected eyes by day 3. ERG analysis indicated depressed signal in the superior region (location of sub-retinal bleb), followed by return to baseline with bleb reattachment in saline eyes only, suggesting scotoma development secondary to loss of retinal function and/or hyperopic shift associated with displacement of the retina from the posterior wall.
Conclusions :
The study has demonstrated the feasibility of achieving transient or sustained retinal detachment in the nonhuman primate by the subretinal delivery of saline or viscoelastic, and that duration of detachment is correlated to the viscosity of the injected fluid. The study has additionally demonstrated the feasibility of quantifying anatomic, functional and physiological features of RD.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.