Abstract
Purpose :
In the surgical setting, subretinal injections are typically accomplished via a transvitreal approach after pars plana vitrectomy (PPV). PPV is an invasive procedure with its own set of inherent risks, including but not limited to: cataract formation, endophthalmitis, and retinal tear or retinal detachment. We have developed a new method and device (Orbit Subretinal Delivery System; OSDS) for making microinjections into the subretinal space via a suprachoroidal pathway while leaving vitreous intact. Using a porcine model, we tested the ability of the OSDS to create subretinal blebs, and monitored the retention over time.
Methods :
In order to demonstrate the utility of the device we created 100 and 200 µl subretinal blebs of various diluents and assessed the physical characteristics including; intraocular pressure, bleb retention, and retinal anatomy after the surgery in 12 adult pig eyes. The procedure involved creating a sclerotomy to gain access to the suprachoroidal space, then cannulating with the OSDS. Once the cannula was in place, a microneedle was extended from the cannula through the choroid to access the subretinal space and create a bleb. OCT and fundus images were taken at 0, 30, and 60 minutes post injection to assess bleb retention.
Results :
Subretinal blebs were successfully created in 100% of the procedures. Bleb retention in the subretinal space at 1hr yielded positive results 92% of the time in live porcine eyes under direct fundus and OCT imaging. Bleb retention appeared to remain stable throughout the duration of observation. Average IOP measurements increased immediately after injection of diluent and receded slowly back to baseline pressure during the 1 hour observation time frame. Retinal perforation and leakage of diluent to the vitreous was avoided 100% of the time.
Conclusions :
The proposed OSDS and suprachoroidal surgical approach can consistently deliver fluid to the subretinal space; that fluid is retained subretinally after cannula withdrawal. The proposed OSDS is not dependent on vitrectomy for subretinal access but instead is designed to access the subretinal space from the suprachoroidal space. Elimination of vitrectomy could significantly improve the risk to benefit ratio for subretinal injection procedures such as those for gene therapies.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.