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DALK results prove safe

DALK procedure provides stable long-term visual and refractive outcomes

Dermot McGrath

Posted: Friday, December 1, 2017

Deep anterior lamellar keratoplasty (DALK) provides safe and stable long-term visual and refractive outcomes, with reduced rates of endothelial cell loss and a lower risk of graft rejection compared to penetrating keratoplasty (PK), Vincent Borderie MD told delegates attending the 8th EuCornea Congress in Lisbon.
“DALK decreases the long-term endothelial cell loss, which results in a significant increase in long-term graft survival. There is also a lower incidence of glaucoma with DALK compared to PK, so I think the take-home message is that DALK is really a safer procedure than PK,” he said.
Dr Borderie, in practice at the Quinze-Vingts Hospital in Paris, France, said that many surgeons hesitate 
before making the transition to DALK for corneal 
stromal disorders.
“There is a learning curve with DALK. It is a difficult technique to master, it is time-consuming and it can be stressful for the surgeon,” he said.
Despite these hurdles, improvements in DALK techniques over the past decade, as well as greater surgical familiarity with that particular approach, are resulting in a greatly reduced conversion rate to PK procedures, said Dr Borderie.
While a variety of different DALK techniques are available, including dry dissection, hydrodissection, “big bubble”, air needle and cannula DALK, Dr Borderie said that in his experience the best results are obtained using Dr Anwar’s “big bubble” technique to treat bare Descemet’s membrane.
When the big bubble approach is not feasible, manual dissection of the stroma is still a viable option, said Dr Borderie.
“The most interesting development in this respect in recent years involves the use of intraoperative OCT, which allows the surgeon to control the depth of dissection and assessment of bare Descemet’s membrane,” he said.
One of the key advantages of DALK is that it removes the central corneal stroma while leaving host corneal endothelium and Descemet’s membrane intact, said 
Dr Borderie. This results in less endothelial cell loss and ultimately a reduced risk of immune rejection.
In one prospective study of 690 consecutive keratoplasties (448 PKs and 242 lamellar keratoplasties) for stromal disorders carried out between 1993 and 2013 by one surgeon, the graft survival was 93% for lamellar procedures and around 75% for PK after 240 months, said Dr Borderie.
Another retrospective study by Dr Borderie of 142 consecutive DALK cases compared to 142 PK cases found an average five-year postoperative endothelial cell loss of 22.3% in the DALK group and -50.1% in the PK group. The long-term, model-predicted graft survival and endothelial densities were higher after DALK than after PK, he said.
While DALK graft failures still occur due to infection and trauma, new technologies such as femtosecond-assisted DALK should help in the near future to reduce the failure rate even further, he concluded.

Vincent Borderie: vincent.borderie@upmc.fr