These rates have been decreasing over the last decade and this has been ascribed to improved eye banking procedures. However, surgeons need to be made aware of the microbiological condition of the received donor tissue. This may include information regarding the risk of tissue contamination, the decontamination steps and measures taken during processing, the storage procedure, the antibiotics that may have been used and the results of any microbiological tests that may have been performed (see section on corneal storage).

Tissue Evaluation Aspects

Enucleation allows for a more extensive anterior segment evaluation by a slit lamp, while examination in situ examination is often limited by the use of a penlight. This examination is important to determine if there has been previous anterior segment surgery or if there is any pathology of the eye that may not have been identified through the donor screening process. However, the examination of the excised cornea in the eye bank laboratory is possible by the slit lamp. The endothelium is the primary layer responsible for the maintenance of corneal hydration and transparency. Tests to assess the functional capacity of the endothelium cannot be applied during eye banking as they affect corneal viability. Therefore, one has to rely on the morphology of the endothelium to reflect its functional reserve and routine inspection of the endothelium is nowadays part of the donor evaluation. Assessment of the cornea by biomicroscopy of the endothelium also provides a quantifiable means of determining suitability for use and helps to increase the donor supply by objectively assessing corneas that may otherwise be arbitrarily excluded for transplantation beforehand on the basis of, for example, age or post-mortem time. While studies linking graft outcome with morphometric parameters of the endothelium are lacking, models to calculate cell loss over extended periods after penetrating keratoplasty have been presented [7, 8]. They provide a rationale for accepting a minimum donor cell density. Many eye banks consider about 2,000 cells/mm2 to be a minimum in cases of where transplantation of the endothelium is involved. In addition, an endothelial layer with considerable polymegathism or pleomorphism and/or the presence of guttae is considered indicative of a cornea that may be functionally deficient or compromised [9]. Ultimately, however, the final decision regarding use rests with the surgeon for each individual patient transplant procedure undertaken while taking the Eye Bank’s evaluation report into account.

Corneal Storage

For the whole eye, the most common storage method is moistened pot or moist chamber storage at 2–6°C, introduced in 1937 [1]. Today this technique is usually a temporary holding or transport method that precedes corneoscleral button excision.

Today the prevailing storage methods are those of placing the corneoscleral button in a modified tissue culture medium. The cornea is then stored hypothermically at 2–6°C, a method introduced in 1974 by Mc Carey and Kaufman, or