Deep lamellar keratoplasty results comparable to or better than PKP, surgeon says

The deep lamellar approach produces transparent corneal grafts with optimal visual results and the advantage of retaining patient’s own endothelium.

Issue: March 1, 2004

ByMichela Cimberle

Lamellar trephination about 2/3 of recipient cornea.	Cross incision of the cornea with sclerotome knives.
Lamellar dissection in the four delimited quadrants.	Linear peripheral incision down to Descemet’s membrane.
Stromal dissection with a gliding rotating movement by means of a blunt spatula.	Recipient Descemet’s membrane layer.
Double running 10-0 nylon suture.	Intraoperative complication management: Small peripheral Descemet’s perforation is fixed with a single 10-0 nylon suture.
Same case as in Figure 8, 1 month later.	(All figures courtesy of Fernando Trimarchi, MD.)

Results of deep lamellar keratoplasty in more than 500 cases performed by one surgeon confirm that the technique has visual outcomes comparable to or better than penetrating keratoplasty and the advantage of preserving the patient’s own endothelium.

“The few of us who have treated a very large number of patients can now state with absolute confidence that DLKP is indicated in all the cases of stromal damage in presence of a healthy endothelium,” said Fernando Trimarchi, MD, of Pavia University Eye Clinic, Italy.

He has been performing this technique since 1998, and some of his patients are now approaching 6 years of follow-up.

Straightforward procedure

Prof. Trimarchi carries out DLKP with a blunt spatula without the use of liquids or air bubbles.

He begins by delimitating the area of the graft with a circular trephination. Inside this area, two perpendicular incisions are performed, penetrating 2/3 of the stromal thickness and dividing the corneal button into four quadrants. The four segments are then removed with a diamond knife.

“At this point I penetrate deeper into the stroma with a blunt knife until I reach the Descemet’s membrane, which can be recognized by its translucency. Using a blunt spatula and circular movements, I create a semicircular tunnel, which is then opened with Vannas scissors, and from there I progressively separate the stroma from the Descemet’s plane,” he explained.

He believes that this straightforward procedure is safer and that the risk of perforation is lower than with the use of air or liquids.

“Other surgeons report a 30% rate of perforation with the use of viscoelastics. M. Anwar with the technique of big bubble reports 9% of perforation. I have reached with my technique about a 4% rate of perforation,” he pointed out.

Moreover, in case perforation occurs, it is easier to take remedial measures using this technique, Prof. Trimarchi said.

“In some cases I have been able to suture the perforation, start again in a different position and carry out the procedure without converting it into penetrating keratoplasty. With needle and visco, this would not be possible, and once the perforation occurs there is nothing you can do but shift to a different procedure,” he said.

Advantages

The results of patients undergoing DLKP were systematically compared with those undergoing penetrating keratoplasty, and results favor the lamellar procedure, according to Prof. Trimarchi.

The main advantage is the possibility of maintaining the patient’s endothelium, he said. This is particularly important in young keratoconus patients because in many cases surgeons resort to corneal grafting.

“The procedure fully respects the endothelium. One year after surgery, the endothelial cell count is 2,208 cell/mm², which means that the average decrease in endothelial cell density is less than 10%. This compares favorably with the endothelial cell count 1 year after [PKP], which is about 1,300 cell/mm². Moreover, with a lamellar grafting there is no risk of endothelial rejection, and healing is much faster,” Prof. Trimarchi said.

For many years, lamellar keratoplasty had been abandoned for corneal transplantation. This was due to the poor visual results obtained after it was first developed in the 1960s and ’70s, he said.

“Visual acuity was low because the interface between the donor’s lamella and the recipient’s cornea was irregular and, like frosted glass, was not sufficiently transparent,” Prof. Trimarchi explained.

In those days, however, dissection was performed more superficially within the stromal tissue, he said. With the deep lamellar technique, the stroma is loosely attached to Descemet’s membrane, and the excision can be carried out evenly and easily, which obtains a smooth surface and better visual results.

“Mean visual acuity at 12 months is near 20/25, and in a good number of patients it achieves 20/20. These results are better than those of penetrating keratoplasty, where mean visual acuity is around 20/32,” Prof. Trimarchi said.

Contrast sensitivity was also evaluated over 1 year. Results with DLKP and PKP were not significantly different, which confirmed the transparency of the lamellar graft.

Mean astigmatism was low, in the range of 3 D, he said.

Few complications

Complications are rare, according to Prof. Trimarchi. Even the risk of perforation should not be a concern; a skilful surgeon can prevent it in most cases, and if it occurs, the surgeon can handle it successfully, he said.

“In case of microperforation, all you need to do is inject an air bubble into the anterior chamber and carry on as normal. With larger perforations, if you use the technique I suggested, you can easily apply a suture and find a different point from where you can carry out the dissection of the lamella. Macroperforations are rare. I only had three cases in 508 patients. The only thing you can do is convert the procedure into penetrating keratoplasty,” Prof. Trimarchi said.

Postoperative complications include stromal inflammation and stromal rejection.

“Stromal rejection is not as severe as endothelial rejection and is easily treated with topical corticosteroids. It occurred in 40 of my patients,” he said.

New vascularization occurred in 23 patients. They were all cases of corneal trauma, and none were keratoconus.

“Looking at these results, there is no reason why DLKP should not be used in all the cases where the endothelium is healthy. It can be performed at all stages of keratoconus, even at the third stage if the surgeon has sufficient experience with the procedure,” he said.

He added that surgical time is reasonably short if the surgeon has had sufficient training.

“Now it takes me 30 to 40 minutes at the most,” he said. “It has become routine surgery, and in many cases, if the patient lives near enough to the clinic, I do it in day hospital regimen.”

Source: Trimarchi F.

For Your Information:

Fernando Trimarchi, MD, is head of Pavia University Eye Clinic. He can be reached at Clinica Oculistica, Dipartimento di Scienze Sensoriali, Università di Pavia, I.R.C.C.S. Policlinico S. Matteo, P.le Golgi 19, 27100 Pavia, Italy; 39-0382-526213; fax : 39-0382-527006; e-mail: trimarch@unipv.it.

References:

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Tsubota K, Kaido M, Satake Y, Bissen-Miyajima H, Shimazaki J. A new surgical technique for deep lamellar keratoplasty with single running suture adjustment. Am J Ophthalmol. July 1998;126(1):1-8.

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Krumeich JH. Choose DLKP whenever you can, surgeon says. Ocular Surgery News. 2001;12:45-46.

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