In Vitro and Ex Vivo Models for Ophthalmic Drug Delivery

The development of effective ophthalmic drug delivery systems is challenged by the eye’s complex anatomy, dynamic barriers, and unique physiology, which limit drug penetration and complicate preclinical evaluation. While in vivo animal models have traditionally assessed ocular pharmacokinetics and safety, their use faces ethical, economic, and translational limitations. Consequently, in vitro and ex vivo ocular models have become essential for mechanistic studies, formulation screening, and device optimization, offering controlled, reproducible, and scalable alternatives. However, challenges remain in model standardization, physiological relevance, and predictive accuracy, especially in translating findings to human clinical outcomes.Advances in tissue engineering, microfluidics, and biomaterials have enabled sophisticated ocular models that better replicate the microarchitecture and function of specific eye compartments. Technologies such as 3D bioprinting and organ-on-a-chip systems simulate corneal, conjunctival, and anterior segment environments, facilitating detailed investigation of drug-tissue interactions, release kinetics, and biocompatibility. Despite these innovations, critical gaps persist in validating these models against human in vivo data, particularly regarding immune responses, long-term safety, and prediction of therapeutic efficacy for advanced drug delivery systems. The absence of consensus on model selection, endpoints, and benchmarking hinders regulatory acceptance and broader adoption.This Research Topic aims to advance the field by focusing specifically on the development, validation, and translational application of in vitro and ex vivo models for ophthalmic drug delivery, emphasizing their predictive value for human outcomes. The collection prioritizes studies that rigorously benchmark model performance, address standardization and reproducibility, and provide mechanistic or translational insights beyond basic formulation testing. Contributions integrating advanced biomaterials or microengineering approaches are welcome if they directly enhance model fidelity or validation. Submissions should present clear methodological advances, validation data, or translational relevance, extending beyond generic formulation screening or device prototyping.Topic of interest include, but are not limited to:- Development and benchmarking of in vitro and ex vivo models for corneal and anterior segment drug delivery, with quantitative comparison to in vivo or clinical data- Application of microengineered platforms (e.g., organ-on-a-chip, 3D bioprinting) to simulate ocular barriers and drug transport- Standardization, reproducibility, and validation frameworks for ocular model use in drug delivery research- Mechanistic studies of drug-tissue interactions, release kinetics, and biocompatibility using validated ocular models- Modeling and assessment of immune responses and inflammation relevant to ocular drug delivery- Translational case studies demonstrating predictive value of ocular models for human pharmacokinetics or therapeutic outcomes Topic editors: Raj Thakur, Maud Gorbet Source: https://www.frontiersin.org/research-topics/86954/in-vitro-and-ex-vivo-models-for-ophthalmic-drug-delivery