Processing Corneas for Grafting

Abstract

This chapter describes all of the important steps between the procurement and storage of corneal tissue intended for grafting, that is, the criteria and contraindications for tissue donation, donor screening, tissue retrieval, macroscopic examination of the donor eye, tissue decontamination, and the preparation of corneoscleral discs or corneal lamellae for subsequent storage. Corneal transplantation (keratoplasty) is, with respect to the risk of disease transmission, a very safe procedure. Today, detailed screening of donor tissue is obligatory, and standards for donor evaluation and testing are typically defined by national legislation. Contraindications to ocular tissue transplantation encompass major communicable diseases such as AIDS, hepatitis B, hepatitis C, degenerative disorders of the brain, and specific malignancies (i.e., lymphoma, leukemia). Whole eye enucleation and in situ excision are the two main approaches to corneal tissue retrieval. The surface of any ocular tissue intended for transplantation must be decontaminated at least once before tissue storage, such as before in situ excision or after enucleation, generally using a polyvinylpyrrolidone-iodine solution. Similarly, a macroscopic assessment of the whole eye has to be performed with the aim of excluding unsuitable tissue from transplantation. While in situ cornea excision is closely associated with hypothermic storage, enucleation often precedes the storage of a cornea in organ culture. Corneoscleral discs for penetrating keratoplasty or various types of lamellae, particularly for posterior lamellar keratoplasties, may be routinely processed in eye banks.