Development of 3D‐printed devices for the study of transscleral drug delivery on freshly excised whole porcine eyes

Purpose: Ex vivo ocular models are a valuable tool for quick screening ophthalmic formulations through permeation and retention studies. We hereby present a 3D‐printed set‐up consisting of a combination of two devices, allowing for the ex vivo study of transscleral drug delivery with fresh whole swine eyes. Methods: The two devices were drafted on a CAD (computer aided design) software and 3D printed with three different printing techniques: selective laser sintering (SLS), fused deposition modelling (FDM) and masked stereolithography (MSLA). The first device was designed to guarantee the contact between drug formulation (liquid or semisolid) and the scleral surface in a defined permeation area for up to 24 h. The second device was then designed to maintain up to three ocular bulbs at constant temperature (37°C) and humidity values. Results: MSLA 3D printing technique was selected due to its versatility, superior print detail and a low unitary cost. In addition, the other two explored techniques delivered relatively porous prints that do not guarantee the required water and air tightness of the devices. The first device was optimized in order to maximize adherence onto the scleral surface and thus anatomically adjusted to porcine scleral curvature. Firm anchorage onto the ocular surface was achieved through a ring‐shaped vacuum chamber easily controlled with a syringe. The second device allowed to immobilize the ocular bulb during the experiment, preserve ocular hydration, and maintain a fixed working temperature by placement into a water bath. Conclusions: The developed ex vivo set‐up, based on the whole porcine eye, could be suitable to perform permeation and accumulation studies of transscleral applied ocular formulations.