Study: Early graft failure more likely with DALK than PK

Invest Ophthalmol Vis Sci. 2009;50(12):5625-5629.

Deep anterior lamellar keratoplasty for keratoconus showed a markedly higher early failure rate than penetrating keratoplasty, according to a large study conducted in the United Kingdom.

The higher early failure rate for deep anterior lamellar keratoplasty (DALK) correlated with surgeon experience, the study authors said.

"It is possible, therefore, that this difference in graft survival between DALK and PK in the U.K. data will decrease as surgical experience improves," they said. "The trend in graft survival after the two procedures will be investigated in future analyses."

The study included 2,372 initial grafts for keratoconus reported between 1999 and 2005; of these, 1,917 grafts were for PK and 455 grafts were for DALK. Follow-up data on 2,152 transplants (91%) were collected and analyzed.

Study data showed that DALK grafts failed at twice the rate of PK grafts (P = .006). In addition, 19% of DALK failures and 2% of PK failures occurred within the first 30 days after surgery.

Excluding early failures, DALK and PK grafts had similar survival rates at 3 years after surgery — 92% and 94%, respectively.

DALK failures primarily stemmed from graft and interface opacification, while irreversible rejection accounted for most reported PK failures, the authors said.

Patients who underwent DALK and PK had mean logMAR best corrected visual acuity of 0.24 at 2 years; 33% of PK patients and 22% of DALK patients had best corrected visual acuity of 6/6 at 2 years. Significantly more DALK patients were myopic, the authors said.