Endothelial keratoplasty has come a long way since the inception of the idea of a posterior lamellar transplant instead of full thickness penetrating keratoplasty. With better understanding of the mechanism and increased surgical experience it has become the procedure of choice for management of corneal decompensation.
DLEK(1956-99) Deep Lamellar Endothelial Keraotoplasty. Involves replacing the posterior stroma-DM-Endothelial complex of the host with the donor lenticule.
DSEK/DSAEK(2004) Descemet’s Stripping (Automated) Endothelial Keratoplasty. Melles et al introduced this technique of stripping the host DM followed by transplanting donor stroma-DM-Endothelial lenticule, which is around 100-130μ thick and is attached to the denuded stroma with air tamponade after injecting in anterior chamber.
Depending on the technique of preparation of lenticule by Manual dissection (DSEK) or by using an automated keratome, it is termed as DSAEK.
For insertion of the lenticule, two techniques are described depending on whether the lenticule is ‘pulled in’ the anterior chamber using various glides (Busin/Endoglide) or ‘pushed in’ the AC using sheets glide.
After insertion of the lenticule, it is attached to the recipient stroma with an air tamponade maintaining the orientation being enotheium down while taking care of least manipulation and trauma to the endothelium. Donor lenticule detachment appears to be the most common complication requiring surgical intervention (rebubbling with air) with fairly good attachment rate of ≈74%.
DMEK Descemets’ Membrane Endothelial Keratoplasty. In this technique DM is stripped from the donor corneoscleral button, trephined to a proper size to form a roll, which is injected in the AC through a 3mm incision. DM-Endothelial role is opened in AC maintaining the orientation and attached with the help of air. Since the optically active donor stroma is not transplanted, it provides a faster vision recovery, better final visual activity and potentially low rejection rates. But being technically more challenging it has high dislocation and primary failure rates. Also there is a risk of tissue loss due to DM tear while preparing the graft.
PDEK Pre Descemets’ Endothelial Keratoplasty. The donor roll is prepared by pneumatic dissection between the posterior stroma and the pre descemets’layer (Dua’s layer). This gives 15-20μ more thickness to the DM-endothelium complex and ease of handling during transplantation.
Also with increasing understanding of the endothelial cell migration physiology, Non transplant method DWEK (Descemetorhexis Without Endothelial Keratoplasty) is being proposed to describe the surgical removal of Descemet membrane (DM) without subsequent endothelial transplantation in the treatment of Fuchs Endothelial Corneal Dystrophy.
DMET Descemet Membrane endothelial Transfer - descemetorhexis with a “free-floating” graft secured in the main incision leading to subsequent corneal clarity is a new concept which is being studied now by harnessing the ability of corneal endothelial cells to migrate and proliferate.
Dr. Chirag Mittal
MBBS, DNB, FLVPEI
Cornea & Ant. Segment
Centre for Sight, Delhi