The eye is a complex sensory organ that enables visual perception of the world. The dysfunction of any of these tissues can impair vision. Conduction studies on laboratory animals are essential to ensure the safety of therapeutic products directly applied or injected into the eye to treat ocular diseases before eventually proceeding to clinical trials. Among these tissues, the cornea has unique homeostatic and regenerative mechanisms for maintaining transparency and refraction of external light, which are essential for vision. However, being the outermost tissue of the eye and directly exposed to the external environment, the cornea is particularly susceptible to injury and diseases. This review highlights the evidence for selecting appropriate animals to better understand and treat corneal diseases, which rank as the fifth leading cause of blindness worldwide. The development of reliable and human-relevant animal models is, therefore, a valuable research tool for understanding and translating fundamental mechanistic findings, as well as for assessing therapeutic potential in humans. First, this review emphasizes the unique characteristics of animal models used in ocular research. Subsequently, it discusses current animal models associated with human corneal pathologies, their utility in understanding ocular disease mechanisms, and their role as translational models for patients.

Eye drops represent 90% of all currently used ophthalmic treatments. Only 0.02% of therapeutic molecules contained in eye drops reach the eye anterior chamber despite their high concentration. The tear film efficiently protects the cornea, reducing access to the target. Thereby, the increase in the drug bioavailability and efficiency must come from the mucoadhesion optimization of the drug delivery system. The gold nanoparticles, used as a drug delivery system in this study, already showcased ultrastable and mucoadhesive properties. The goal was to study the gold nanoparticles’ ability to release two specific ophthalmic drugs, flurbiprofen and ketorolac. The parameters of interest were those involving the loading conditions, the gold nanoparticles properties, and the release experimental conditions. The drug release was measured using an in vitro model based on dialysis bags coupled with UV–visible spectroscopy. Gold nanoparticles showed an ability to release different molecules, whether hydrophobic or hydrophilic, in passive or active drug release environments. Based on these preliminary results, gold nanoparticles could represent a promising drug delivery system for ketorolac and flurbiprofen when topically applied through eye drops.

Effective drug delivery is essential in the treatment of ocular diseases. However, one of the main challenges remains the low bioavailability of drugs at target sites when administered as eye drops, which account for 90% of all ophthalmic treatments. New nanosystem-based delivery methods are needed to maintain adequate drug concentrations over time and improve therapeutic outcomes. To overcome obstacles to topical ocular drug delivery and improve their precorneal retention time for better therapeutic efficacy, gold nanoparticles have emerged as a promising approach to enhance drug bioavailability to the eye. It is therefore crucial to understand the biodistribution profiles of gold nanoparticles in the eye. In this study, in vivo ocular biodistribution is assessed in rabbits up to 24 h after administration of eye drops containing fully characterized polyethylene glycol-modified gold nanoparticles (AuNPs@PEG₂₀₀₀). The results provide a better understanding of the in vivo biolocalization of ultrastable AuNPs@PEG₂₀₀₀ in various ocular tissues and their potential use as drug delivery systems by demonstrating their in vivo mucoadhesive properties on the ocular surface. A significant amount of AuNPs@PEG₂₀₀₀ is particularly observed in the cornea after gold atom assay by ICP-MS, up to 6 h after exposure to the eye drop, despite the many physical and physiological barriers on the ocular surface. We believe that this AuNPs@PEG₂₀₀₀ accumulation in the cornea can be considered as an advantage for controlling long-term drug release rates. Thus, this residence time of AuNPs@PEG₂₀₀₀ holds promise for improving topically-applied ocular treatments in future drug delivery research.