## 4 Discussion
The authors proposed that the maintenance of cornea transparency and the prevention of stromal edema are related to the high osmolarity of the solutions, which was around 365 mOsm/kg in Optisol-GS. The Chen medium (CM) differs from Optisol-GS mainly by the presence of \(\beta\)-hydroxybutyrate in its composition, a ketoacid that has been found to stimulate corneal endothelial cell proliferation. [PERSON] et al. [38] compared CM and Optisol-GS stored corneas for 48 h, reporting no significant difference in the corneal thickness. However, this study investigated a relatively short time of preservation, limiting the generalization to the needsof most eye banks. Later, [PERSON] et al. [31] observed no difference in corneal thickness from baseline in CM stored corneas after one week of storage, but this parameter increased dramatically from 1 to 2 weeks of storage [31; 38]. While longer preservation times need to be investigated to appropriately compare the adequacy of CM compared with Optisol-GS, two different clinical trials have identified very similar clinical outcomes after using Chen medium or Optisol-GS in penetrating keratoplastics with preservation under 7 days [39; 40]. Presently, Optisol-GS does not include any antifungal additive. In addition, its colorimetric indicator, phenol red, does not reliably detect _C. albicans_ contamination. The Eye Bank Association of America (EBAA) medical advisory board did not recommend antifungal supplementation of corneal storage media, partly because of insufficient evidence regarding efficacy and safety. In this context, [PERSON] et al. [28] investigated the inclusion of voriconazole and amphotericin B as additives to Optisol-GS in reducing _C. albicans_ and _C. glabrata_ contamination under normal storage conditions. Their findings suggest that a low concentration of amphotericin B might be a safe and efficacious addition to storage media, even though more extensive studies are necessary to confirm these data [41]. In this sense, another medium containing an antimyotic tablet is Kerasave, which presented 2.5 ug/mL of amphotericin B and which was recently studied by [PERSON] et al. [30], in a comparison that evidenced properties comparable with Optisol-GS in terms of corneal preservation at 2-8 \({}^{\circ}\)C for 14 days. The final approval by the FDA for Kerasave is still pending, as it has been delayed during the COVID-19 pandemic. As an important exception, Cornea Cold was the cold storage medium that presented better results in all qualitative parameters and tests compared with Optisol GS, from 1 to 14 days. According to [PERSON] et al. [13], the usual assessments employed to evaluate preservation media are subjective since there is still no standardized protocol for corneal preservation at eye banks, making it difficult to recommend a specific media for conservation before surgery. Therefore, the authors propose the standardization of the evaluation of cornea quality through a quantitative overall quality (QQ) assessment that integrates different comparative parameters such as thickness, transparency, viable endothelial cell density (VECD), and morphology on a four-point numerical scale, including longer preservation times up to 28 days, widely used in the technique of organ culture at 31 \({}^{\circ}\)C [13]. With such methodology, the authors identified similar OQ rates for Cornea Cold with a one-week delay compared with Optisol-GS and, therefore, proposed a maximum storage time of 21 days. Such a longer preservation time proposed for Cornea Cold could theoretically be beneficial for long-route international transportation of surplus corneas to countries with higher demand for human corneal tissues. The authors also propose that the main advantage of Cornea Cold is the maintenance of thinner tissues with high transparency, which could allow for better observation and manipulation for earlier visual rehabilitation.