DXEK heralds a new era in corneal transplantation

May 31, 2007

The shift to descemetorhexis with endokeratoplasty (DXEK), which is synonymous with Descemet stripping endothelial keratoplasty, represents "an exciting period in corneal surgery with the move from sutures to sutureless corneal transplantation," according to Thomas John, MD, Loyola University at Chicago, Maywood, IL, United States.

The shift to descemetorhexis with endokeratoplasty (DXEK), which is synonymous with Descemet stripping endothelial keratoplasty, represents "an exciting period in corneal surgery with the move from sutures to sutureless corneal transplantation," according to Thomas John, MD, Loyola University at Chicago, Maywood, IL, United States.

When choosing the trephine diameter, Dr. John advised that surgeons adhere to the diameter. Exceeding the disc diameter will result in problems with unfolding the disc. When cutting the donor disc, the screws should be tightened twice. Loose screws, Dr. John noted, will cause tissue slippage, resulting in an uneven cut and thickness of the donor disc.

He also noted that use of the 300-µm head eliminates the need for pachymetry without perforation. When punching the donor disc, the tissue should be stained because the absence of staining can cause eccentric trephination.

Dr. John recommended a 5-mm wound. A wound that is under 3.5 mm causes endothelial cell damage because of decreased space and the resultant tissue compression. Dr. John advised achieving good hemostasis, without which heme can enter the interface and compromise vision.

In addition, one of the most important factors in this surgery is remaining in the correct plane when removing Descemet's membrane. An improper plane causes stromal membrane damage, a compromised interface, and resultant poor visual acuity.

He also recommended the use of a stromal scrubber. This instrument increases the disc attachment by roughening the edges of the disc. All ophthalmic viscoelastic device (OVD) (Healon, Advanced Medical Optics) should be removed from the anterior chamber before disc transplantation. All OVD also should be removed from the taco fold as well.

The donor disc is conventionally implanted in a 60/40 fold with 20% of the endothelium exposed. Folding the tissue in an 80/20 fold increases the endothelial exposure to 60%, Dr. John said. The less endothelium that is exposed, the lower the chances are of endothelial damage. When inserting the taco, air that is injected in a steady controlled manner will avoid flipping of the taco.

Finally, Dr. John advising using a large air bubble to hold the disc in place during implantation. A small air bubble accelerates detachment. The diameter of the air bubble should be greater than the donor corneal disc.