LIMBAL ALLOGRAFT

ive symblepharon patients, including two that failed multiple prior reconstructions, were successfully treated with a novel approach in which keratolimbal allografts were used to cover conjunctival defects, Nancy Lee MD, ophthalmologist at Kaiser Permanente in San Diego, California, US, told the 2014 American Society of Cataract and Refractive Surgery symposium in Boston.

In all five cases ocular motility was restored and diplopia in primary gaze resolved, Dr Lee reported. No symblepharon recurrences onto the keratolimbal graft segments were observed, though mild recurrences up to the edges of the grafts were seen in two patients. Subsequent placement of additional keratolimbal segments resulted in restoration of full range of ocular motion, she said.

The results suggest that keratolimbal allograft segments are a robust tissue alternative to amniotic membrane or mucosal autografts traditionally used for treating symblepharon, Dr Lee said. The keratolimbal allografts, similar to those used to treat limbal stem cell deficiency, created an effective mechanical deterrent to symblepharon reformation. That they also contained healthy limbal and conjunctival stem cells may also have helped prevent symblepharon recurrences by contributing to a healthy ocular surface, Dr Lee said.

Sticky problem

Symblepharon occurs when trauma, disease or allergy cause adhesion of the palpebral conjunctiva of the eyelid to the bulbar conjunctiva of the eyeball. A frequent result is limitation of ocular movement, which may lead to clinically significant diplopia in primary and/or lateral gaze.

Surgical treatment involves release of symblepharon with resection of associated subconjunctival fibrotic tissue followed by reconstruction of the ocular surface. If not enough conjunctiva is left at the site to cover the entire surface defect, amniotic membrane, conjunctival autograft, or oral or nasal mucosal autografts are typically used to cover the remainder.

However, recurrences are common, even when adjuvant therapies such as intraoperative mitomycin C, symblepharon ring spacers and postoperative subconjunctival steroid injections are employed, Dr Lee noted. Autografts also present issues of tissue availability and potential complications at the donor site.

The technique Dr Lee reported was conceived by Marjan Farid MD, her co-author and preceptor at UC-Irvine, she said. Tissue preparation is similar to limbal cell transplant, using a 7.5mm punch. The central button is discarded and the corneal scleral rim sectioned. The posterior lamella is excised with crescent blades, and corneal edges tapered. The segments are then custom tailored to cover the conjunctival defect without overlapping and secured with fibrin glue. Typically multiple segments are used.

Symblepharon resulted from trauma in all five patients Dr Lee treated. Two had failed repeated prior treatment, including autografts and subconjunctival steroids, but have now recovered with no recurrence at 12 and 18 months' follow up.

“We have achieved functional and anatomical success in all of our patients so far,†she said.

Nancy Lee: nancyleemd@gmail.com