Accumulating evidence provides encouraging data with inserter

October 1, 2009

A disposable Descemet stripping automated endothelial keratoplasty (DSAEK) donor inserter has several advantages that suggest it offers a safer alternative to conventional donor folding techniques.

San Francisco-A proprietary disposable Descemet stripping automated endothelial keratoplasty (DSAEK) donor inserter (Tan EndoGlide, Network Medical Products) has several potential advantages that suggest it offers a safer alternative to conventional donor folding techniques, and it has been associated with encouraging results in initial clinical experience, reported Donald T.H. Tan, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.

"Reducing endothelial damage remains the major challenge in endothelial keratoplasty today," said Dr. Tan, medical director, Singapore National Eye Centre. "With taco folding techniques, the endothelial cell loss rate is in the range of 30% to 35%, and the rate of primary graft failure has been reported to be as high as 45%.

"Surgeons using the Busin glide [KeraMed] with a pull-through technique have also reported endothelial cell loss rates in the range of 25% to 28%," said Dr. Tan, who also is professor of ophthalmology, National University of Singapore. "Preliminary results from studies in human eye-bank eyes showed endothelial cell damage rates were reduced from 32% with taco folding to 9% using the Sheets glide technique and to only 5.3% using the [new disposable inserter]."

Technique

Before it is inserted into the new device, the donor lenticule is prepared by coating its endothelial surface with a small amount of viscoelastic. Then it is loaded in a double-coiled fashion into the transparent plastic insertion chamber.

The chamber is sealed with a backplate and attached to a handle that is used to insert the flat capsule portion into the anterior chamber through a 4- to 4.5-mm incision.

With an anterior chamber maintainer in place and using an endoforceps in a pull-through technique, the lenticule is withdrawn from the cartridge into the eye, taking care that the forceps grips only the stromal surface. The donor automatically uncoils, with gentle shaking of the forceps, and once positioning of the lenticule is completed, a small air bubble is placed into the anterior chamber to ensure the donor stays up against the cornea.

"Using the [new disposable inserter], there is no risk for iris prolapse or contact between the donor tissue and the incision, and in theory, the double-coiling of the lenticule should reduce endothelium-to-endothelium contact," Dr. Tan said. "In addition, the procedure is completed in a closed eye system so that the anterior chamber remains stable throughout, and since the lenticule is held with the endoforceps after it is removed from the inserter, the surgeon retains full control over the graft while it is being oriented within the anterior chamber."

He presented several cases performed using the new disposable inserter, including the first two that were combined phacoemulsification-DSAEK procedures. At 1 month, the grafts were clear, the two patients had unaided vision of 20/30 and 20/40, respectively, and the endothelial cell loss rate was less than 14% in both eyes.

Currently, eye bank studies are being performed to collect more data on endothelial cell loss associated with use of the new disposable inserter, including comparisons with other recently developed inserters.

In addition, a 100-patient, institutional review board-approved clinical trial is under way, and further revisions in the device design are being considered, including the creation of a smaller version.