Near-Real Surgical Specimens (NRSS): A Novel Platform for Standardized Assessment of Suprachoroidal Drug Delivery

Purpose: Suprachoroidal (SC) drug delivery is a promising avenue for treating posterior segment ocular diseases. Current ex vivo models, primarily human cadaveric eyes, are limited by tissue variability and altered post-mortem fluid dynamics. We introduce near-real surgical specimens (NRSS), an engineered ocular tissue platform, to overcome these limitations and provide standardized, reproducible evaluation of SC drug delivery.

Methods: NRSS ocular models were engineered with biomimetic properties calibrated to fresh human tissue. Suprachoroidal injections of a contrast-enhanced balanced salt solution (100 µL) were performed in NRSS specimens (n = 8) using the Everads Suprachoroidal Injector, which features a 30-gauge needle and a non-sharp nitinol tissue separator for tangential blunt dissection into the suprachoroidal space (SCS). An integrated contrast imaging system enabled real-time visualization. Key parameters, including SC coverage patterns, interspecimen variability (coefficient of variation [CV]), and injection dynamics, were quantified and compared to published human cadaveric eye data.

Results: The NRSS platform demonstrated consistent SC coverage patterns. With the Everads Suprachoroidal Injector, injectate exhibited an initial posterior diffusion from the injection site, followed by postero-circumferential spread. NRSS specimens showed significantly reduced inter-specimen variability in SC coverage compared to reported cadaveric studies (CV: 6.8% for NRSS vs. 17.7% for cadaveric tissue; P < 0.01). Real-time visualization provided detailed insights into the dynamic characteristics of SC injection, including fluid flow patterns and tissue interactions not readily observable in static cadaveric models.

Conclusions: The NRSS platform offers a reproducible and standardized method for evaluating SC drug delivery, closely mimicking clinically relevant biomechanical properties. It enables direct visualization of injection dynamics and holds potential for customization to model pathologic conditions, providing distinct advantages over traditional cadaveric models for device testing, therapeutic assessment, and surgical training. The Everads Suprachoroidal Injector demonstrated effective and reliable access to the SCS in NRSS models with a characteristic posterior-first spread pattern.

Translational relevance: NRSS technology addresses critical limitations in current SC injection assessment models. It provides a robust, standardized platform for optimizing delivery devices, quantitatively evaluating novel therapeutics, and enhancing surgical training for SC procedures, thereby potentially accelerating the clinical translation of SC therapies.