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DALK with acellular corneal tissue may reduce graft rejection risk
Deep anterior lamellar keratoplasty yielded a higher long-term graft survival rate with acellular glycerol-preserved corneal tissue than with fresh corneal tissue, a study found.
Acellular glycerol-cryopreserved corneal tissue (GCCT) was particularly more effective than fresh corneal tissue (FCT) in high-risk cases presenting with corneal neovascularization or inflammation, the study authors said.
“GCCT offers an outstanding advantage of a significantly higher long-term graft survival rate with no graft rejection and is preferable over FCT in DALK for high-risk corneas,” Wei Chen, MD, PhD, the corresponding author, told Ocular Surgery News in an email interview.
Cryopreserved acellular tissue lacks antigen-presenting cells and others that spur graft rejection, Chen and colleagues said.
Additionally, GCCT is available at a significantly lower cost than FCT and may help alleviate global shortages of donor corneal tissue, Chen said.
“This approach has great significance in developing countries, where cornea collection programs and infrastructure for eye banking are deficient,” he said. “In the United States alone, the use of glycerol as a means of preservation could increase the cornea donor pool by 7,000 to 8,000 corneas annually.”
Patients and methods
The prospective, randomized study, published in the American Journal of Ophthalmology, included 68 eyes of 68 patients with a mean age of 48.2 years who underwent DALK with FCT or GCCT.
Thirty patients had herpes simplex virus keratitis, 15 had bacterial keratitis, 14 had fungal keratitis and nine had thermal burns.
Removal of residual stromal tissue via manual dissection aided by hypotonic liquid allowed direct visualization of the dissection and resulted in a decreased Descemet’s membrane micro-perforation rate of just five out of 68 eyes, Chen said.
“Hypotonic liquid induces visible edema of residual stroma fibers due to osmotic pressure, helping the surgeon to hook them for complete removal,” he said. “This technique allows direct visualization of the dissection and avoids the opacity resulting from injection of air or viscoelastic materials.”
A full-thickness graft without endothelium and Descemet’s membrane and with a diameter 0.25 mm greater than the host bed was affixed with 16 interrupted 10-0 nylon sutures.
Snellen best corrected visual acuity and microscopy were assessed 1 week and 1, 3, 6, 12 and 24 months postoperatively.
Visual acuity, graft survival
Study results showed that 57.6% of eyes in the GCCT group and 54.8% of eyes in the FCT group had postoperative BCVA of 20/40 or better at final follow-up; the difference was not statistically significant.
No cases of graft rejection occurred in the GCCT group; 10 cases of stromal rejection occurred in seven eyes in the FCT group.
The rejection-free graft survival rate at 2 years was 100% in the GCCT group and 78.8% in the FCT group; the between-group difference was statistically significant (P = .006). The graft survival rate was 100% in the GCCT group and 93.9% in the FCT group; the difference was not statistically significant.
Rejection rates varied according to indications for surgery, Chen said. – by Matt Hasson
- Li J, et al. Am J Ophthalmol. 2011;doi:10.1016/j.ajo.2011.05.002.
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- For more information:
- Wei Chen, MD, PhD, can be reached at School of Ophthalmology and Optometry, Wenzhou Medical College, 270 Xueyuan West Road, Wenzhou, Zhejiang, 325027, People’s Republic of China; email: chenweimd@hotmail.com.
Disclosure: Chen has no relevant financial disclosures.