Amniotic membrane transplantation safe and effective in ocular surface reconstruction

Amniotic grafting is well tolerated, never rejected, and represents a favorable substrate for conjunctival tissue regeneration.

ByMichela Cimberle

NAPLES, Italy – The use of human amniotic membrane for ocular surface reconstruction is finding increasing consent among surgeons.

“In comparison with other biologic tissues used as reconstructive grafts, the amniotic membrane presents some undoubted advantages,” said Claudia Martello, MD, of Venice-Mestre Hospital, at the meeting of the Italian Ophthalmologic Society. “It is thinner and better tolerated by the patient and it never becomes necrotic. It is not a substitute of the conjunctiva, but rather a substrate where conjunctival cells migrate and regenerate, forming new and healthy tissue.”

The amniotic membrane is the deeper layer of fetal membrane. It is avascular, multilayered tissue with anti-angiogenetic, anti-tumoral and anti-inflammatory properties. Since it does not produce antigens of histocompatibility, the membrane is never rejected by the receiving tissues.

“Also, the beneficial effects of reducing inflammation and neovascularization persist after the membrane has been absorbed,” Dr. Martello pointed out.

Amniotic membrane preparation, storing

The studies of the Venice-Mestre Eye Clinic are coordinated by Elisabetta Bohm, MD, head of the clinic, and carried out in cooperation with one of the main institutions for eye banking in Italy, also located in Venice. The placentas were obtained after caesarean delivery under sterile conditions, from mothers who signed an informed consent.

“Donor selection is performed by criteria additional to the Medical Standards of the Eye Bank Association of America,” said Diego Ponzin, MD, of the Veneto Eye Bank. “Donors are tested for HIV, hepatitis B and C, TPHA, cytomegalovirus and toxoplasma IgM. They must also demonstrate the absence of fetal abnormalities and familiar genetic diseases. Serologic examinations are repeated 6 months after donation. The placenta is washed with sterile saline and the amniotic membrane is carefully detached from the underlying chorion. It is then rinsed, cut into patches and laid, epithelial side-up, onto a cellulose nitrate filter. The filters are then inserted into cryovials filled with cryopreservation medium and stored in liquid nitrogen fumes at approximately –140° C until surgery. Samples for microbiologic testing are taken from each step of the process. Fresh and post-storage samples of amniotic membrane are studied histologically, to exclude the presence of inflammatory and neoplastic cells, and to evaluate the architecture of the tissue.”

Three successful cases

Dr. Martello mentioned three cases of amniotic membrane transplantation. The first case was a 78-year-old male affected by bilateral pemphigoid associated with corneal ulcer and entropion. “We resected the conjunctiva in the upper and lower eyelid up to the fornix, and replaced it with amniotic membrane tissue. The nylon suture was removed after 15 days. During a period of 2 months we observed the progressive absorption of the membrane and the reconstruction of the fornix. The entropion was corrected thereafter,” she said.

The second patient was a 57-year-old male with monolateral ankyloblefaron from chemical burns. The skin of the upper eyelid adhered to the nasal corneal limbus. “We debrided the upper eyelid and the conjunctiva from the scar adhesions, which extended over 180°. Then we reconstructed the internal canthus and the entire fornix with amniotic membrane,” Dr. Martello said. Silk sutures were removed from the fornix after 1 week, nylon sutures after 15 days.

The third case was a 62-year-old male with recurrent pterygium and corneal leukoma. “In this patient, the opacity was so widespread and the head of the pterygium so deeply infiltrated to the Descemet’s membrane level that we had to perform a lamellar keratoplasty. At the same time, we resected the entire conjunctiva and replaced it with amniotic membrane tissue. Sutures were removed after 2 weeks. The amniotic membrane was progressively absorbed and replaced by new, healthy conjunctival tissue,” Dr. Martello said.

In all cases the amniotic membrane was applied with the epithelial layer facing upwards and the patients were treated with local antibiotic and steroid drops and with artificial tears for 20 days.

Appearance of amniotic membrane.	In one case, a 78-year-old male patient was affected by bilateral pemphigoid associated with corneal ulcer and entropion.
The scars were debrided, the conjunctiva resected and the amniotic membrane implanted.	At 2 months postop a new fornix had formed.
In a second case, a 57-year-old patient had monolateral ankyloblefaron from chemical burns.	The skin of the upper eyelid was separated from the corneal epithelium, the adhesions were debrided and the internal canthus and fornix were reconstructed with amniotic membrane.
Postoperatively a new fornix has formed, with no synechiae.	In a third case, a 62-year-old patient had a recurrent pterygium.
The conjunctiva was resected, a lamellar keratoplasty reformed and amniotic implantation performed.	Postoperatively the internal canthus has reformed and conjunctival tissue has regrown.

For Your Information:

Claudia Martello, MD, and Elisabetta Bohm, MD, can be reached at Ospedale Umberto I, Via Circonvallazione 50, Mestre-Venezia, Italy; +(39) 041-2607407; fax: +(39) 041-2607146. Dr. Martello has no direct financial interest in any of the products mentioned in this article, nor is she a paid consultant for any companies mentioned. Diego Ponzin, MD, can be reached at Fondazione Banca degli Occhi del Veneto, Via Felisatti 11, Mestre, Italy; +(39) 041-989777; fax: +(39) 041-985255. Dr. Ponzin has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.