DALK offers higher rate of corneal endothelial survival than PK, study shows

Ophthalmol. 2009;116(12):2354-2360.

Deep anterior lamellar keratoplasty appeared more suitable for younger patients than penetrating keratoplasty, because preservation of the corneal endothelium allowed longer graft survivability, a study showed.

PK was more appropriate for older patients because graft survival appeared to coincide with patient life expectancy, the study authors said.

"For corneal diseases not involving the endothelium, deep anterior lamellar keratoplasty seems to be a promising therapeutic approach with higher long-term expected survival," they said.

The cohort study included 1,144 eyes of the same number of patients who underwent PK or DALK between 1992 and 2006. Mean patient age was 58.4 years. Patients were assigned to three groups; 701 patients with impaired endothelia underwent PK, 361 with normal endothelia underwent PK and 82 with normal endothelia underwent DALK.

Patients were examined frequently between 1 week and 15 years after surgery. The average follow-up interval was 40.5 months. Primary outcome measures were endothelial cell loss, time to graft failure and long-term graft survival. Investigators recorded data prospectively and analyzed them retrospectively.

Study data showed that an estimated 74% of grafts survived at 5 years and 64% of grafts survived at 10 years. Average endothelial cell density was 2,270 cells/mm² before surgery, 1,604 cells/mm² at 1 year, 1,321 cells/mm² at 3 years, 1,058 cells/mm² at 5 years and 865 cells/mm² at 10 years. Average endothelial cell loss was 29.7% at 1 year, 42.4% at 3 years, 52.7% at 5 years and 60.7% at 10 years.

Observed and predicted graft survival rates were higher in patients who underwent DALK than in those who underwent PK with normal endothelia, and higher in those with normal endothelia who underwent PK than in those with impaired endothelia who had PK, the authors said.