This page provides answers to frequently asked questions related to the handling, evaluation, transport, storage, and processing of corneal tissue and associated storage media. The aim is to ensure best practices are followed consistently to maintain tissue quality and patient safety.

The cornea is not sterile and is collected in a microbiologically non-controlled environment. To safely decontaminate without damaging the endothelium, the procedure should be performed before incision and extraction. The recommended method is to decontaminate the eye bulb with 5% povidone-iodine prior to the procedure.
Alternatively, if the entire eye bulb is procured from the donor, an additional decontamination with 5% povidone-iodine can be performed at the eye bank before cornea excision.

It is recommended to assess the cornea condition immediately upon arrival to determine transplant suitability. Corneas deemed unsuitable for transplant should be redirected for non-transplant uses or discarded. According to the European Eye Bank Association “slit lamp examination is mandatory and, if possible, the endothelium shall be examined to estimate endothelial cell density (ECD).” [EEBA Technical Guidelines for Ocular Tissue (TGOT), Rev.11, §2.3].

Additionally, endothelium mortality can be monitored following staining with viable dye Trypan Blue.

It is suggested to rinse the cornea by gentle immersion into PSS-L rinsing solution prior to examination.

The validated and suggested method is to transport the cornea in a refrigerated medium at 2-8°C using Corneal Chamber. If it becomes necessary to adopt a different method and Tissue-C is used directly after retrieval, it is preferable to transport the cornea at room temperature minimizing the transport time as much as possible; however, it is essential to transfer the cornea into a second vial of Tissue-C upon arrival at the eye bank. This step is crucial to prevent prolonged exposure to debris and contaminants present in the initial vial, which, among other factors, originates from the non-sterile environment during tissue retrieval, thereby significantly reducing the risk of contamination.

Before use, thaw the solution in the refrigerator (2–8°C) overnight, or at room temperature (20-25°C) for up to 4 hours until complete thawing, or in a water bath at 37±2°C for up to 30 minutes. After thawing, stir the solution
The 37°C water bath poses risks of temperature fluctuation and vial contamination. Always sanitize vials with isopropanol before use.
If alternative thawing methods are used, it is important to ensure the temperature does not exceed the recommended maximum and that the thawing time is validated. This is necessary to avoid damaging the storage medium.

No, refreezing is not permitted. After thawing, store the medium in a refrigerator for up to 24 hours before use is allowed.

This method is strongly discouraged due to contamination risk. A sterile corneal floating component (Cornealfloat) is provided to keep the cornea suspended safely within the medium.

The validated minimum volume is 80 mL of Tissue-C.

Trypan Blue can be used to assess corneal quality but must be used carefully. Our validated protocol is 0.25% Trypan Blue concentration in saline for 30 seconds (never exceeding 60 seconds).

The cornea should be stored and transported at room temperature.

1. Donor cornea disinfection performed by immersing the tissue in 40 mL of 1% iodine solution for 3 minutes under a laminar flow hood, followed by a rinse in normal saline, has been shown to reduce contamination rates from 73% to just 4%.
2. Pels and Vrensen concluded that immersion of human donor eyes in 5 mg/ml PVP-I solution for 2 minutes significantly reduces microbial contamination of donor corneas without relevant penetration of iodine into the corneal layers.
3. Decontaminating measures such as the treatment with povidone-iodine and the addition of antibiotics to the preservation medium decrease the frequency of microbial growth.
4. An aseptic setting for donor enucleation similar to a surgical procedure seems not to influence the outcome of germ colonization. The most effective step to decontaminate donor eyes is to use 0.75% povidone iodine solution for at least 3 minutes.
5. Among antiseptics, PVPI has the distinctive property of acting on bacteria, fungi, and viruses. When used at a concentration of 5 mg/ml (0.5%) for two minutes, it reduces eye contamination by half without causing corneal damage. Even a 5 minutes immersion time results in bacterial decontamination rates of 86% to 100% with a confidence level of 95%.
6. Because corneal tissues from deceased donors usually bear microbial and/or fungal contaminants, a standard decontamination procedure is mandatory before enucleating the ocular globe or exciding the corneoscleral button to reduce the contamination rate. Methods of the study: 5% povidone–iodine (Oftasteril) solution for 2 minutes.

1. Badenoch P, Alfrich S, Wedding T, Coster D. Decontamination Method for Donor Corneas. Br J Ophthalmol. 1988;72:225-227.
2. Pels E, Vrensen GFJM. Microbial decontamination of human donor eyes with povidone-iodine: Penetration, toxicity, and effectiveness. Br J Ophthalmol. 1999;83(9):1019-1026.
3. Zanetti E, Bruni A, Mucignat G, Camposampiero D, Chiara Frigo A, Ponzin D. Bacterial Contamination of Human Organ-Cultured Corneas. Cornea. Published online 2005.
4. Laubichler P, Arend N, Vounotrypidis E, et al. Comparing Different Decontamination Procedures in Harvesting Human Donor Cornea. Curr Eye Res. 2016;41(9):1173-1177.
5. de Faria e Sousa SJ, de Faria e Sousa SB. Eye bank procedures: Donor selection criteria. Arq Bras Oftalmol. 2018;81(1):73-79.
6. Vignola R, Giurgola L, Colabelli Gisoldi RAM, Gaudio M, D’Amato Tóthová J, Pocobelli A. Monitoring the microbial contamination of donor cornea during all preservation phases: A prospective study in the Eye Bank of Rome. Transpl Infect Dis an Off J Transplant Soc. 2019;21(2):e13041.