The effect of amniotic membrane grafting on healing and wound strength after strabismus surgery in a rabbit model.

Background: Amniotic membrane grafts (AMGs) are used, with mixed results, as a platform for ocular healing and to reduce pathologic scarring. This study evaluated wound tensile strength and histopathologic changes after strabismus surgery with AMGs in 20 New Zealand white rabbits.

Methods: All subjects underwent 4 mm inferior rectus hang-back recessions to both eyes. The right eyes served as controls. Ten left eyes (group 1) received processed dehydrated amniotic membrane allografts (Ambiodry2, IOP Inc, Costa Mesa, CA) and ten left eyes (group 2) received cryopreserved human amniotic membrane allografts (AmnioGraft, Bio-Tissue, Miami, FL) between the sclera and muscle insertion and between the muscle and repositioned conjunctiva. At postoperative month 1, tensile strengths of the muscle-globe and conjunctiva-globe attachments were measured, and histopathologic analysis of each eye was performed.

Results: In group 1 the mean tensile strength of the muscle-globe attachments was 441.4 ± 274.4 g; of the conjunctiva-globe attachments, 640.3 ± 266.4 g. In the control eyes, the comparable values were 365.8 ± 199.8 g and 595.2 ± 315.3 g, respectively (P = 0.19, P = 0.13). In group 2 the mean tensile strengths were 456 ± 297.5 g and 608.2 ± 306.7 g, compared with control values of 352.7 ± 114.8 g and 583.8 ± 347.1 g (P = 0.43, P = 0.45).

Conclusions: There was no significant change in tensile strength of the muscle insertion using AMGs. In a rabbit model, AMGs do not reduce inflammation or improve scar formation 1 month after strabismus surgery.