Each human eye bank eye, obtained less than 36 hours post mortem through Bio Implant Services, Leiden, and the Cornea Bank of the Netherlands Ophthalmic Research Institute, Amsterdam, was mounted on a custom made eye holder).

Through a paracentesis, the anterior chamber was completely filled with air. A 4.0 mm peripheral corneal incision was made, and with a custom made spatula set, a stromal pocket was dissected across the cornea at 80% stromal depth, using the air-to-endothelial interface as a reference plane for dissection depth. A plastic strip was inserted into the pocket, and a corneo-scleral rim was gently excised from the globe. The rim was mounted endothelial side up onto a punch block, and with a 7.0 or 7.5 mm punch trephine a full-thickness corneal button was excised.

Note: The first two patients showed postoperative pachymetry readings of less than 500 um, following stromal dissection of the donor and recipient cornea at the same stromal depth. Thinning of the donor posterior tissue after surgery may be explained by the fact that relatively more post mortem hydration, i.e. swelling is present in the posterior than anterior cornea. Thus, the actual depth of dissection in a post mortem cornea may be deeper than intended. For example, a dissection made at 80% depth in a post mortem, swollen cornea may equal a 90% dissection depth in a physiologically hydrated cornea. Thus, in donor corneas a dissection may be made at 80% depth, to obtain an eventual recipient corneal thickness of approximately 550 (m.

For the technique described in Chapter 4, the button was placed endothelial side down onto a custom made, spoon-shaped glide covered with visco-elastic substance (Hydroxypropylmethylcellulose, Ocucoat, Storz, Clearwater, FL, USA). Then the anterior lamella and the plastic strip at the lamellar interface were removed, so that a posterior lamellar disc was in situ on the glide.

For the technique described in Chapter 5, the posterior lamellar disc was placed stromal side down onto a custom made inserter, and the endothelium was covered with visco elastic to protect the endothelium during the implantation of the donor tissue.

Endothelial cell counts
Preoperative endothelial cell counts were obtained by counting the number of endothelial cells in a standard size grid, with light microscopy. Postoperative donor endothelial cell counts were obtained from the central cornea by non-contact specular microscopy (Topcon SP2000p, Tokyo, Japan). For each measurement, three endothelial photographs were taken at the central cornea. Photomicrographs were analyzed (Imagenet 2000, Topcon, Tokyo, Japan) and manually corrected, before cell densities were calculated by the software and averaged.