Corneal transplants are the most common transplantation procedures in medicine, and it is well-established that a successful corneal transplant outcome depends primarily on the presence of a viable corneal endothelium (Nishimura et al., 1999). Corneal endothelial cells (ECs) regulate stromal hydration by using Na+/K+-ATPase pumps to regulate water balance. Without the pump mechanism, bare stroma swells to several times its thickness, resulting in disruption of stromal fibers, increased light scatter, and decreased corneal transparency (Bonanno, 2012). Corneal endothelium is not capable of regeneration, thus making preservation of the endothelium during tissue storage and transplantation critical for optimization of surgical outcomes (Bonanno, 2012). Therefore, the main objectives of a corneal storage system are to maintain EC viability and to preserve corneal structure.

In the United States, donor corneas are typically preserved in a unicameral chamber containing Optisol-GS (Bausch & Lomb; Rochester, NY, USA) under hypothermic conditions (2–8 °C) prior to transplantation (America, 2018; Armitage, 2011). Although this method allows for storage up to 14 days, 96 % of grafts are used within 7 days of recovery (Armitage, 2011; Lass et al., 2015). In contrast, European practices often involve organ culture media at 31 °C, extending storage time up to four weeks (Armitage, 2011). Despite various explorations into media compositions and storage methods, the standard for corneal storage in the United States has remained largely unchanged since the widespread adoption of Optisol-GS in the early 1990s (Kaufman et al., 1991).

It is well-established that cold storage negatively impacts EC viability and corneal structure. The number of viable ECs decreases over time at 4 °C (Komuro et al., 1999). Cell death leads to the breakdown of the epithelial barriers that preserve stromal thickness; therefore, as storage time increases, stromal thickness increases, and corneal transparency is compromised (Komuro et al., 1999). According to Nishimura et al., corneal grafts with late endothelial failure, which is the major cause of graft failure after five postoperative years, fail from low initial EC density rather than from an increased rate of chronic postoperative cell loss (Nishimura et al., 1999). Additionally, it has been shown that endothelial cell characteristics in donor tissue, such as maturity, has significant impact on transplantation success rate (Kitazawa et al., 2023). Therefore, preserving endothelial viability during storage and transplanting less edematous corneal grafts should have protective effects on the endothelium after transplantation (Nishimura et al., 1999).

In the current corneal storage model, the entire graft is submerged in the same preservation media for the duration of storage (Wojcik et al., 2021). However, the corneal epithelium and endothelium exist in distinct physiological microenvironments and have different metabolic requirements. The epithelium serves as a protective external barrier, continuously exposed to environmental insults, and regenerates frequently with high cell turnover (lifespan of 7–10 days), leading to increased metabolic demands (Sridhar, 2018). In contrast, the endothelium faces the anterior chamber and has limited regenerative ability (Sridhar, 2018). Notably, current corneal storage vials do not reflect this separation, as both layers are submerged in the same media.

Our group has developed a novel dual-chamber corneal storage vial (DCV) consisting of two compartments separated by the corneal graft itself. One compartment contains preservation media in contact with the endothelium, while the other is in contact with the epithelium. The DCV can serve as a platform for discovery and innovation, including potential applications in media customization. Prior to conducting such studies, the safety of separating the compartments and reducing media volumes must be established. This study aims to evaluate the safety and efficacy of the DCV in preserving human corneal grafts compared to the standard single-chamber vial (SCV).