Effect of cryopreserved amniotic membrane on the development of adhesions and fibrosis after extraocular muscle surgery in rabbits.

PURPOSE: To histopathologically evaluate the effect of cryopreserved human amniotic membrane (AM) transplant on preventing the development of postoperative adhesions after extraocular muscle surgery. METHODS: Ten albino rabbits were used. The superior rectus muscles were bilaterally resected. In right eyes, the muscle was wrapped with cryopreserved human AM (group AM). In left eyes, the muscle was not wrapped with AM and served as a control group (group C). The rabbits were killed, and the eyes were enucleated 6 weeks after surgery to perform histopathological examination. RESULTS: On histopathological examination, the AM was present in eight eyes, surrounded by periamniotic inflammation, with no adhesions detected between rectus muscle and sclera, conjunctiva and Tenon's capsule in the segment where the AM was present, but detected elsewhere. Adhesions were detected in the other two eyes of group AM, in which the AM was absent, and in all group C eyes. When comparing eye pairs of each rabbit, AM eyes showed significantly less adhesions between the muscle and sclera (p = 0.009) and between the muscle and Tenon's capsule and conjunctiva (p = 0.008), in the region of AM application, and significantly more foreign body inflammation (p = 0.031), than C eyes. The differences between AM and C eye pairs, in terms of conjunctival inflammation and vascularity and muscle fibrosis, were insignificant (p > 0.05). CONCLUSIONS: Cryopreserved AM is effective in reducing postoperative extraocular muscle adhesions. Its application is, therefore, recommended during strabismus reoperations.

Effect of lyophilized amniotic membrane on the development of adhesions and fibrosis after extraocular muscle surgery in rabbits.

PURPOSE: To histopathologically evaluate the influence of lyophilized human amniotic membrane transplant on the development of postoperative adhesions and fibrosis after extraocular muscle surgery. METHODS: Ten albino rabbits were used. The superior rectus muscle was resected 4 mm in both eyes. In right eyes, the superior rectus muscle was wrapped with lyophilized (air-dried, freeze-dried) human amniotic membrane (group AM). In left eyes, the superior rectus muscle was not wrapped with amniotic membrane, and served as a control group (group C). The rabbits were sacrificed and the eyes were enucleated 6 weeks after surgery to perform histopathological examination. RESULTS: Two rabbits died 1 week after surgery and were excluded. Histopathological evaluation of both eyes of the remaining 8 rabbits was done. The amniotic membrane was not seen in all eyes. On comparing eye pairs of each rabbit, right eyes showed significantly less conjunctival inflammation (p = 0.034), but insignificantly less foreign body inflammation (p = 0.625), adhesions between sclera and muscle (p = 0.206), muscle fibrosis (p = 1.000), and conjunctival hyperemia (p = 0.059) as compared to left eyes. CONCLUSIONS: Lyophilized amniotic membrane insignificantly reduces postoperative adhesions and fibrosis, when used to wrap the operated upon extraocular muscles, limiting the benefit of this membrane in strabismus surgery.