electron and light microscopic study of the interface in deep lamellar keratoplasty with the big-bubble technique

purpose: to determine the dissection level during deep lamellar keratoplasty (dalk) using the big-bubble technique by light microscopy (lm) and transmission electron microscopy (tem). methods: descemet’s membrane (dm) and stromal tissue of 4 keratoconic eyes were removed because of inadvertent intraoperative dm perforation during dalk which was converted to penetrating keratoplasty. these specimens were divided in two halves, one half was fixed in 10% formalin for lm, and the other half was fixed in 2.5% glutaraldehyde for tem. results: lm examination of the corneal stromal and dm specimens, disclosed scattered round empty spaces consistent with air bubbles within the stroma, and pas-positive membrane with adherent endothelia on one side and scant amounts of posterior stroma including keratocytes on the other side. conclusion: separation of stromal corneal tissue from dm during dalk using the big-bubble technique for keratoconic eyes occurs within the deep stromal tissue near dm.