How Viable is the Endothelium of Optisol–GS Stored Human Corneas Left at Room Temperature (23 degree C) for 72–96 hours vs. 4 degree C Stored Corneas?

Abstract

Abstract: : Recently in eye bank circles the question has arose if denial of refrigeration would adversely affect the viability of the corneal endothelium and thus the suitability for transplantation of Optisol–GS stored human corneas if they were allowed to remain at room temperature for several days before transplantation. Purpose. To determine if corneal endothelial viability is compromised in Optisol–GS stored eye bank corneas left at room temperature for 3–4 days. Methods. After receiving Optisol–GS stored human corneas (n=20) from the Georgia Eye Bank (age range 48–74 yrs), one of each pair was placed on a lab bench (at 23ºC) for 72 to 96 hours. The fellow cornea was stored for the same amount of time at 4ºC. For the 72 hr group (n=10 corneas), the mean±SD age was 63.4±5.4 yrs, the mean±SD death to enucleation time was 4.7±1.2 hrs, and the mean±SD storage time (not including experimental time) was 8.0±2.3 days. For the 96 hr group (n=10), the mean±SD age was 65.4±11.8 yrs, the mean±SD death to enucleation time was 5.9±3.5 hrs and the mean±SD storage time was 6.6±2.9 days. After their experimental (72 or 96 hrs) storage time, each cornea was bisected and half was removed for scanning (SEM) and transmission (TEM) electron microscopy while the remaining half was stained for 45–60 minutes using a live cell/dead cell stain (Molecular Probe, Eugene, OR). Photos were taken with a fluorescent microscope and assembled into a montage where live cells stain green and dead cells stain red. Dead cells were identified and analyzed using NIH Image software to determine % damage. Mean±SD were calculated for each cornea along with p values. Results For the 72 hr group, the 4ºC corneas show 2.3±1.6 % damage vs. 2.7±2.5 % for 23ºC corneas. In the 96 hr group, 4ºC corneas have 11.1±5.3 % damage vs. 15.7±8.5 % for 23ºC corneas. There is no significant difference in % damage when comparing 4ºC data with 23ºC data in either storage time. However, the % damage at 96 hrs is significantly increased at both 4ºC and 23ºC when compared to 72 hrs (p= 0.008 at 4ºC and p= 0.012 at 23ºC). SEM and TEM show minimal damage at 72 hrs especially at 4ºC with more damage at 23ºC with some endothelial cell edema and junctional breakdown. At 96 hr, electron microscopy reveals greater endothelial damage including more dead or dying cells especially at 23º C. Conclusions Lack of refrigeration up to 72 hours for Optisol–GS stored human corneas seems to be fairly well tolerated by the corneal endothelium. However, past 72 hours significantly more damage occurs decreasing endothelial viability.

Keywords: cornea: endothelium • cornea: storage • cornea: basic science