Abstract
Purpose :
Potential spaces in anatomy refer to the area between apposed organs or tissues and can represent “druggable” targets, including the epidural space, used to deliver anesthetics, and the suprachoroidal space (SCS), currently undergoing clinical trial with several therapeutics. In clinical trials, optical coherence tomography (OCT) imaging has demonstrated acute and transient opening of the SCS in preclinical and clinical studies. This imaging study characterized the biomechanical response of injection into the SCS in comparison to intravitreal (IVT) injection.
Methods :
Suprachoroidal and IVT injections were performed in ex vivo porcine eyes and the biomechanical response was visualized using the imaging modalities: external photography, spread visualization via ultraviolet (UV) with fluorescence, internal endoscopy, and cryo-freeze sectioning under microscopy. Suprachoroidal injections were performed with the SCS Microinjector®. IVT injections were performed with a 1-mL syringe and standard 30-G needle. Tissues change, injectate spread, and globe behavior were analyzed for both therapeutic delivery methods.
Results :
Imaging modalities demonstrated differences between suprachoroidal and IVT injection in distribution of injectate, tissue change, and globe behavior. When evaluated under UV light, suprachoroidal injection of fluorescing particles showed spread circumferentially and posteriorly. No injectate spread was visible with IVT injection, as fluorescence is muted by the pigmented choroid and RPE. Cryofreezing and section showed suprachoroidally injected injectate spread posteriorly toward the macula, between sclera and choroidal tissues. IVT injection showed a bolus of injectate located in the vitreous. Endoscopic footage of an ex vivo porcine suprachoroidal injection show a localized depression of the choroidal tissues when the procedure is begun, followed by SCS expansion as fluid is injected. Corresponding imaging during IVT delivery demonstrated differences in spread of injectate within the globe.
Conclusions :
In contrast to intravitreal delivery, suprachoroidal drug delivery results in acute opening of the SCS, supporting the potential to target affected tissue layers in chorioretinal disorders.
This is a 2021 ARVO Annual Meeting abstract.