Endothelial keratoplasty: Graft survival and endothelial cell loss at 5 years and beyond

Fort Lauderdale, FL-Long-term data on deep lamellar endothelial keratoplasty (DLEK) show that most donor tissue remains clear past the 5-year follow-up. Data from a newer procedure, Descemet’s stripping automated endothelial keratoplasty (DSAEK), also are promising and indicate an earlier plateau of endothelial cell loss, said Mark A. Terry, MD, director of corneal services, Devers Eye Institute, Portland, OR.

Dr. Terry presented data on 36 eyes that had undergone DLEK between 2000 and 2003 and had been followed past the 5-year visit. He also reviewed data on cases performed more recently using DSAEK.

In DLEK, a pocket is cut from the back of the cornea, along with stroma; the tissue is placed in the bed or pocket with the edges tucked in. In contrast, in DSAEK a thin piece of donor tissue containing only the endothelial cell layer is placed on the back surface of the recipient’s cornea.

Surgical trauma is the number one cause of graft failure in endothelial keratoplasty; other causes include graft dislocation, graft rejection, and rebubbling. Dr. Terry and colleagues looked at these factors in their first 36 cases of 9-mm incision DLEK; the dislocation rate was 2.8% (1/36), and the primary graft failure rate was zero.

Data from various studies places the endothelial cell loss rate from DSAEK up to 50%, although the loss rate in larger studies is about 25% to 35%. Looking at data on 285 initial cases performed by Dr. Terry and several colleagues, he found that the cell loss rate in that series was 30% at 6 and 12 months and 31% at 24 months.

With the longest follow-up data for DSAEK being from 2 to 3 years, Dr. Terry reviewed DLEK cases to assess long-term outcomes. Of the initial 36 cases of large-incision DLEK at 5 years, 5 patients had died and 5 were lost to follow-up. One eye had late endothelial failure at about 15 months and was successfully regrafted. The outcome for the group overall was 35/36 clear grafts at the time of the last follow-up. Twenty-five eyes remain available for follow-up beyond 5 years.

For small-incision DLEK, 121 eyes are at 2 years, 32 are at 5 years, and 4 at 6 years; more data will be available on these patients in the future, Dr. Terry said.

For large-incision DLEK, analysis of cell loss over time out to 7 years showed continued loss until the 5-year mark, when the loss reached a plateau. For patients receiving small-incisions, dramatic cell loss occurred in the first year or two, while a plateau began to appear at around the 3-year point.

“We compared the two and found that the 5-mm small-incision group had a dramatic drop-off compared with the large-incision group, but then it started to equalize as we got out to 4, 5, and 6 years,” Dr. Terry said.

Comparing DLEK with DSAEK, a dramatic difference in endothelial cell loss occurred over time. In DLEK, patients experienced cell loss between 2 and 5 years before it leveled off. In DSAEK, data show that a plateau is reached as early as 6 months. It is too soon to say whether this trend will change, resulting in additional cell loss. Preliminary results, however, do not suggest this outcome, Dr. Terry said. Further follow-up will determine whether optimism about DSEAK is warranted.