Efficacy, safety data support recommendation to embrace anterior lamellar keratoplasty

San Francisco-In eyes with normal endothelium requiring corneal transplantation, deep anterior lamellar keratoplasty (DALK) using Anwar’s big-bubble technique can result in visual acuity outcomes that are at least as good as those experienced after penetrating keratoplasty (PKP) and with the advantage of causing fewer complications than the full thickness procedure, said Donald H. Tan, MD, deputy director and head, corneal service, Singapore National Eye Centre, and head and professor of ophthalmology, National University of Singapore.

Dr. Tan reported results from a comparison of outcomes in a series of 206 eyes, including 103 eyes that underwent PKP, 52 eyes that had DALK using manual dissection, and 51 eyes having DALK using the big-bubble technique. The three groups were matched by age, race, and diagnosis.

A comparison of vision outcomes based on improvement in Snellen acuity showed a significant advantage comparing PKP with DALK with the manual technique but no difference between the PKP group and eyes that had big-bubble DALK, he said. Analysis of percentages of eyes attaining 20/20, 20/30, or 20/40 acuity showed superior outcomes in eyes having DALK with the big-bubble technique relative to the other two procedures. Visual acuity results were similar looking at a subgroup of eyes with keratoconus, he added.

"We think DALK with the big-bubble technique gives better graft alignment than conventional PKP, and this may explain why it can result in better visual outcomes," Dr. Tan said.

Safety results favored DALK. Endothelial cell loss at 3 years was only 7.7% in the eyes that had DALK with the big-bubble technique compared with 38% in the PKP group. Rates of steroid-related complications, including IOP increase and cataract, also were lower in the DALK group because of shorter-term corticosteroid use. Graft failure rate in the PKP group was about 35%, he said.

Reviewing the literature on this topic, however, Dr. Tan said that not all studies have yielded results consistent with his own series in terms of visual acuity outcomes.

"Obviously, outcomes with DALK are technique-dependent," he concluded.