DSEK technique evolves with experience

As more surgeons learn about DSEK, they are developing better methods of unfolding donor tissue and ensuring fixation.

Francis W. Price Jr.

Unfolding a graft properly during Descemet-stripping lamellar endokeratoplasty and ensuring that the graft is well attached are nuances of this complex procedure that ophthalmologists are beginning to understand better.

Francis W. Price Jr., MD, an early practitioner of the procedure, recently performed Descemet-stripping lamellar endokeratoplasty, or DSEK, at the German Congress of Ophthalmic Surgeons in Nuremberg where he demonstrated his technique.

Dr. Price, an OSN Cornea/External editorial board member, performed the surgery using topical anesthesia to demonstrate that although the maneuvers can be more difficult under these conditions, they are still manageable.

“I usually recommend for the first few cases that people use a retrobulbar block,” Dr. Price told Ocular Surgery News during a telephone interview. “This makes it so there is less chance of movement or squeezing on the patient’s part; it makes it easier for the surgeon.”

He added that there is no need for general anesthesia at any point during the learning of this procedure.

“There’s increased risk with general anesthesia, increased cost, and patients can get sick afterwards,” he said.

Larger numbers of surgeons are performing the procedure, which will hopefully lead to advances in how it is done, Dr. Price said.

Dr. Price noted that DSEK is also often referred to as DSAEK, with the “A” standing for “automated.”

Donor tissue preparation

One of the most recent advances in DSEK, applied by Dr. Price in Nuremberg, was the introduction of a microkeratome for preparing the donor tissue for implantation.

In the past, dissections were done by hand, which meant less control and a poorer quality interface, Dr. Price said. Using a microkeratome makes the interface smoother, which improves visual recovery. It also allows the surgeon to select the best thickness.

“That’s the only way I think anybody should be doing it now unless they don’t have access to a microkeratome,” Dr. Price said.

Using a microkeratome limits the types of artificial anterior chamber that may be used for donor preparation, Dr. Price said.

“The artificial anterior chamber has to have a track or some kind of mechanism for the microkeratome to sit on, so that’s why if you are going to use a microkeratome preparation, then you are pretty much locked into a microkeratome and an artificial anterior chamber that are made by the same company,” Dr. Price explained in the interview.

Dr. Price said he uses the Moria ALTK microkeratome and artificial anterior chamber system.

“Moria has a very nice artificial anterior chamber. I think it’s probably one of the most forgiving ones to put the donor on,” he said.

Variations on the technique

The general surgical technique that Dr. Price uses for DSEK is to create a scleral tunnel and remove the diseased endothelium and Descemet’s membrane of the recipient cornea with the aid of trypan blue. This helps visualize the complete removal of the endothelium inside the cornea, Dr. Price explained.

Once this has been done, the internal lamella is removed from the donor cornea and folded endothelium-on-endothelium in order to protect the cells from any damage during insertion. The tissue is then inserted and unfolded using balanced salt solution. Air is used to push the graft into place.

Ophthalmologists may use this basic structure as a starting point and create their own methods. According to Dr. Price, where he uses a scleral tunnel, others may use a clear corneal incision to insert the graft.

Some surgeons also elect to fold the graft twice for insertion rather than use the standard method of folding it like a taco, allowing them to use a 3-mm incision rather than the standard 5-mm incision, Dr. Price said.

“We’re pretty sure that every time you fold the tissue you’re killing some endothelial cells, so it’s going to be interesting to see how the cell counts differ between these different techniques,” Dr. Price said. “We are going to really get some different approaches and see which way works the best.”

Pearls for unfolding the graft

No matter which technique is used, one of the primary concerns during surgery is making sure that the graft unfolds well and that it is secure in the cornea.

One impediment to proper unfolding can be an anterior chamber that is too shallow. Many times this is due to a cataractous lens that crowds the chamber.

“Normally, if it were a case that I was planning to do, I would take the cataract out ahead of time or at the same time, but preferably ahead of time,” Dr. Price said.

Grafts can also unfold the wrong way if the surgheon is not careful.

“You cannot take your eyes off of [the graft] after you put it in because if you don’t watch it, it could unfold the wrong way and then you will have the endothelial side up,” he said.

Having the correct tissue thickness is also important to proper unfolding, Dr. Price said.

“If the tissue is too thin, sometimes it doesn’t want to unfold just because it doesn’t have enough stromal fibers to bend back into position,” he said.

When problems unfolding the tissue occur, Dr. Price said he will fixate the graft to the cornea at one side and pull it open from the other, making sure to only touch the stromal side of the graft.

Avoiding dislocations

Given that DSEK is a sutureless procedure, grafts can dislocate for a variety of reasons, according to Dr. Price.

Cases in which the wound is not strong and tends to leak are susceptible to dislocations because the tissue is soft, Dr. Price said.

“With a soft eye, when you just blink and squeeze your eyes, you push in the cornea more and that can cause the donor to come off,” he said.

A slick posterior surface of the recipient cornea makes it harder for donor tissue to stick or attach. Dislocations can occur postoperatively no matter what techniques are used. But Dr. Price said the key in his experience is to make sure there is no trapped fluid between the donor tissue and the recipient.

Dr. Price said he began applying two new steps to the procedure to get rid of excess fluid.

“I used a Lindstrom LASIK roller … to move the tissue around in the eye, but also to massage out some of the fluid, and we also make a little incision through the recipient down to the interface, and periodically we drain fluid out of that,” he said.

Dr. Price makes these incisions with a flat-tipped diamond blade from Mastel to open up the incision without having to go too deep.

“If you have a tip on the end, you have to keep pushing it in further and further to get it very wide open, and that can dislodge the donor,” he said.

He then uses a silhouette of this diamond blade to torque the incision without cutting it open more.

“Now that we have hundreds of people doing [DSEK], people are going to come up with different nuances, changes in technique, and we’re going to get better ways to do it,” he said.

For more information:

• Francis W. Price Jr., MD, can be reached at Price Vision Group, 9002 N. Meridian St., Suite 100, Indianapolis, IN 46260; 317-844-5530; fax: 317-844-5590; e-mail: fprice@pricevisiongroup.net. Dr. Price is a consultant for IntraLase.

• Jared Schultz is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses geographically on Europe and the Asia-Pacific region.