Precut corneal grafts yield positive visual outcomes in keratoplasty

Lead study author foresees a growing number of eye banks meeting a rising demand for high-quality grafts.

Marianne O. Price

Precut corneal grafts and surgeon-dissected tissue provided similarly strong outcomes after Descemet’s stripping automated endothelial keratoplasty, according to a study.

Marianne O. Price, PhD, and colleagues reported that the difference in endothelial cell loss between precut and surgeon-dissected corneal grafts was statistically insignificant at 6-month and 12-month follow-up. No patients suffered endothelial decompensation or graft failure, they said.

The most important finding was that trained eye bank technicians are qualified to precut corneal grafts, Dr. Price said in a telephone interview with Ocular Surgery News.

Surgeons were formerly reluctant to relinquish cutting duties to technicians, she said.

“This study demonstrated that the eye bank technicians can do a good job on [the] dissection step,” Dr. Price said. “It’s not controversial anymore. The eye banks are providing thousands of precut grafts.”

An optical coherence tomography image of a precut graft used in Descemet’s stripping automated endothelial keratoplasty. Image: Price Vision Group

She said she expects a growing number of eye banks to meet a burgeoning demand for high-quality precut grafts.

The study was published in the American Journal of Ophthalmology. The authors noted that no previous randomized studies have validated the use of precut tissue for Descemet’s stripping automated endothelial keratoplasty (DSAEK).

Study design and methods

The randomized, prospective, double-masked clinical trial included 40 recipients with a mean age of 71 years. All patients underwent DSAEK at one center; one eye bank provided precut tissue.

Researchers harvested 20 pairs of corneas and randomly assigned them to patients undergoing DSAEK. One cornea from each pair was sent to an eye bank for precutting, and the other cornea was dissected by the surgeon at the time of surgery.

A graft being precut in an eye bank for use in Descemet’s stripping automated endothelial keratoplasty. Image: Iowa Lions Eye Bank

“That eliminated virtually all of the donor variables because each group had the same range of donor ages, death to preservation, death to use and approximately equivalent endothelial cell counts,” Dr. Price said.

Eye bank technicians and surgeons used the CB microkeratome (Moria) to dissect corneas.

Ultrasonic pachymetry was used to measure the central corneal thickness of each donor cornea. If central corneal thickness was more than 575 µm, a 350-µm microkeratome depth plate was used. In cases in which central corneal thickness was less than 575 µm, a 300-µm plate was used.

Unlike surgeons, eye bank technicians were able to inspect precut grafts, Dr. Price said.

“They inspect it with a slit lamp, and they also repeat the endothelial cell count to make sure that there hasn’t been extensive endothelial damage during the cut,” she said. “That’s something the surgeon doesn’t have an opportunity to do in the operating room.”

Precut donor corneas were immersed in Optisol-GS solution (Bausch & Lomb) for shipping. All precut corneas were transplanted the day after being dissected at the eye bank, the authors said.

In all cases, the donor lenticule was folded over a drop of viscoelastic into a taco configuration and inserted into the recipient eye with a single-point fixation forceps. A 5-mm scleral tunnel incision was used in cases that only involved DSAEK. A 5-mm clear corneal incision was used in cases that combined DSAEK and cataract removal.

The same surgical technique was used in all cases. “It was important in this study for us to have the same surgical technique for the precut tissue and the surgeon cut tissue and to make the cutting the only variable that differed between the two groups,” Dr. Price said.

Outcomes and complications

Five eyes with pre-existing retinal disease were excluded from analysis of best corrected vision. At 6-month follow-up, all eyes had best corrected visual acuity of 20/60 or better; 12 of 16 eyes with surgeon-dissected grafts and 16 of 19 eyes with precut grafts attained BCVA of 20/40 or better, the authors reported.

Both groups had a mild hyperopic shift, but neither had a statistically significant increase in mean refractive cylinder. Eyes implanted with IOLs were excluded from spherical equivalent refraction analysis because often the lens was intended to produce a refractive change, the authors said.

Mean endothelial cell loss was 32% at 6 months and 34% at 12 months. Each group had two early graft dislocations; grafts were successfully reattached with a second air bubble. Both groups had similar central corneal thickness at 6 months and 12 months, the authors said.

The study had a few limitations, such as the use of precut tissue only on the following day and the use of a single eye bank. The authors said a larger patient sample would be required to definitively determine if dislocation rates of precut and surgeon-dissected tissue were comparable. However, previous studies suggested that graft dislocation is not a major concern with precut tissue.

For more information:

• Marianne O. Price, PhD, can be reached at Cornea Research Foundation of America, 9002 N. Meridian St., Suite 212, Indianapolis, IN 46260; 317-814-2990; fax: 317-814-2806; e-mail: mprice@cornea.org. Dr. Price has no direct financial interest in the products discussed in this article, nor is she a paid consultant for any companies mentioned.

Reference:

• Price MO, Baig KM, Brubaker JW, Price FW Jr. Randomized, prospective comparison of precut vs. surgeon-dissected grafts for Descemet stripping automated endothelial keratoplasty. Am J Ophthalmol. 2008;146:36-41.

• Matt Hasson is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses on regulatory, legislative and practice management topics.