Specialist shows how to prevent and treat complications in DSAEK

Glide insertion technique helps with the placement of the graft, and air filling with an inferior iridectomy helps to prevent pupillary block.

Massimo Busin

Descemet’s stripping automated endothelial keratoplasty is widely replacing penetrating keratoplasty in patients with a diseased endothelium, according to a specialist.

When correctly performed, the technique leads to optimal visual rehabilitation, with few complications and a low rate of graft rejection, Massimo Busin, MD, said at a meeting earlier this year.

“The idea of doing posterior lamellar grafts goes back to the years when I trained with Dr. Kaufman in 1981,” Dr. Busin said. “We used to perform epikeratophakia, which basically consisted in suturing a tissue lens in front of the eye to change the curvature and, therefore, the refractive power of the cornea. I thought this concept of using tissue lenticules could be extended to different purposes, like replacing a diseased endothelium.”

He experimented in rabbit eyes with a technique that is similar to what is done nowadays with DSAEK. The crucial difference was in the fixation of the graft.

“We sutured the grafts, and this caused a lot of manipulation and damage to the tissue. That’s why we stopped our experiments and never applied the technique to human eyes,” Dr. Busin said.

A few years later, Gerrit Melles, MD, developed his technique and showed that the donor lamella could be fixated with the pressure of a bubble of air.

Safest way to do surgery

DSAEK requires a learning curve, but when it is performed well, it works, Dr. Busin said. Graft preparation can cause limited problems, and if anything goes wrong, it is almost always because of the insertion, the unfolding and the fixation of the graft.

“The mistake most surgeons do is to deal with the graft as if they were dealing with an IOL,” he said. “But we are not dealing with a soft piece of plastic that unfolds spontaneously. We are inserting a piece of floppy tissue that has living cells that can be damaged and requires maneuvers to be placed into position.”

For best, less traumatic placement of the graft, Dr. Busin developed his glide insertion technique. He started with a rudimentary device, but the idea was to roll the graft edge-to-edge, with the endothelium inside to prevent contact with the delicate internal layer during insertion. Only the stroma was touching the edges of the wound.

Soon after, special instruments were developed to facilitate these maneuvers. The Busin glide (Moria) is loaded with the donor lamella, which is then pulled across the anterior chamber by Busin forceps (Moria) inserted at the opposite side, through a temporal paracentesis.

Under continuous irrigation through an anterior chamber maintainer, a deep chamber is kept, and the lamella unfolds spontaneously. During surgery, Dr. Busin uses no viscoelastic because remnants could infiltrate in between the donor and recipient, which would prevent adhesion.

Using this method, cell loss at 1 year averages 23%, but in comparison with conventional PK, less loss occurs in the longer term, he said.

Preventing intraoperative complications

“When injecting the air bubble, if you use a complete air fill, be careful because you can have a pupillary block,” Dr. Busin said.

To prevent this, he combines air filling with an inferior iridectomy, which should be performed with scissors.

“The cut must be a big one, and laser iridectomy is not enough,” he said.

Dr. Busin recommended checking patients a few hours after surgery to make sure that this complication has not occurred; however, a complete air fill is the best way to avoid dislocation.

Special precautions must be taken with patients previously implanted with anterior chamber IOLs. According to Dr. Busin, Kelman-type lenses should be removed because of the danger of endothelial cell loss.

“I remove the lens and change it with a posterior chamber lens, sulcus fixated. Otherwise, I remove the lens, do the DSAEK and re-implant the anterior chamber lens later,” he said.

Iris claw lenses are less problematic and do not need to be removed. However, Dr. Busin said there was a case in which the enclavation was lost. One week after DSAEK, he changed the lens, which was possible without problems for the graft.

Phakic eyes, which are a minority, are not a problem when a pull-through technique is used.

“You can avoid any contact with the lens because the pupil is constricted. You can also place the access tunnel for the forceps slightly above or below the pupil. So if anything drops, it will touch the iris and not the lens,” he said.

A series of patients followed for more than 1 year showed no progression of lens opacity. In eyes with previous glaucoma surgery, there are potential risks of increased pressure with the air injection, reaction to steroids, and graft detachment and graft failure.

“There are still unanswered questions, but in the cases I treated so far, I’ve had no complications. Unless they are phakic or steroid responders, I keep these patients, like all the other patients, on one drop of steroids for life,” Dr. Busin said.

Post-traumatic eyes are also delicate cases because they may require a lot of manipulation, which can lead to bleeding. Extra care must be used, particularly at the dissection stage.

Dealing with postoperative complications

Dr. Busin said the most important sign of a successful procedure is corneal clarity 1 day after surgery. However, corneal opacity is not necessarily a sign of tissue damage.

In most cases, the cause is a double chamber, in which the graft is not properly attached to the posterior corneal surface. This may be because of insufficient air filling, hypotony and poor wound closure, or residual viscoelastic trapped in between the two layers.

“In most cases, a double chamber is clearly visible at the slit lamp, but sometimes it is not. I advise to try to rebubble the eye in all cases where the graft is not clear, even days after the initial surgery. If the maneuver is successful, the cornea will be perfectly clear the next day,” Dr. Busin said.

Late detachment occurs rarely, but always consider the possibility of a double chamber and rebubble the eye. Partial detachment is usually because of an attempt to drag the tissue into position. This maneuver creates folds that prevent adhesion. Debris is a possibility, especially if a scleral tunnel approach is used.

“That’s why I prefer a clear cornea approach,” Dr. Busin said. – by Michela Cimberle

• Massimo Busin, MD, head of the department of ophthalmology at Villa Serena Hospital, can be reached at Via Del Camaldolino 8, 47100 Forli, Italy; e-mail: mbusin@yahoo.com. Dr. Busin received royalties from Moria for the glide and forceps developed to deliver the DSAEK graft carrying his name.