Recent Advances in Alternate Corneal Models for Ophthalmic Safety Testing and Efficacy Studies: A Special Focus on...

Accurate assessment of ocular toxicity, drug safety, and therapeutic efficacy remains a significant challenge due to the complex anatomy and physiology of the human cornea. Furthermore, conventional two-dimensional (2D) cell cultures and animal models have key limitations. Recent advances in alternative corneal models-three-dimensional (3D) tissue-engineered constructs, organ-on-chip platforms, corneal organoids, and bio-printed systems have transformed ophthalmic research by offering improved physiological relevance and translational value. These advanced models better recapitulate the multilayered architecture, biomechanical properties, fluid dynamics, and cellular microenvironment of the native cornea, enabling more accurate investigation of drug penetration, toxicity, wound healing, and disease mechanisms. In alignment with current National Institutes of Health (NIH) initiatives promoting the replacement, reduction, and refinement of animal research and the promotion of New Approach Methodologies (NAMs), this review examines emerging corneal models that collectively represent a paradigm shift in ophthalmic research. We first outline conventional in vivo and in vitro corneal models to provide historical context and their limitations, followed by a discussion of next-generation technologies. These include cornea-on-chip systems that integrate microfluidics to represent tear flow, blinking, and biomechanical forces; corneal organoids derived from pluripotent stem cells that offer self-organizing, human-specific platforms for disease modeling and safety assessment; and advances in 3D bioprinting enabling the fabrication of mechanically adjustable corneal constructs. The review also highlights the importance of bioinformatics/artificial intelligence in predicting ocular responses and complementing experimental platforms. Collectively, we emphasize that these alternative, emerging technologies support ethical science, improve translational accuracy, and meet federal regulations while reducing animal testing.