Integration patterns of cryopreserved amniotic membranes into the human cornea

Abstract

Purpose: Because of the wide spectrum of indications and the different techniques used, amniotic membrane transplantation (AMT) may result in many variants of wound healing. Our aim was to investigate and classify the integration patterns of amniotic membrane (AM) into the human anterior cornea following AMT.

Design: Retrospective, noncomparative, nonconsecutive, interventional case series.

Participants: Twenty-four eyes of 24 patients (age, 64.9+/-13.6 years).

Methods: Eyes underwent penetrating keratoplasty 26.1+/-25.1 weeks (range, 0.3-79) after transplantation of cryopreserved human AM. Histopathologic and ultrastructural examinations were performed on the excised corneal buttons.

Main outcome measures: Patterns were classified according to the topographic relationship between AM and corneal epithelium. The respective thicknesses of the corneal epithelium and AM layer(s) were measured.

Results: Integrated AM was found in 18 of 24 corneas up to 79 weeks after transplantation. Amniotic epithelium was present in only 4 of 24 cases with intracellular signs of degeneration. Amniotic membrane stroma was integrated in 4 patterns: (1) intraepithelial (4 eyes); (2) subepithelial (11 eyes); (3) intrastromal, with various grades of retraction (4 eyes); and (4) superficial localization--AM present on the corneal surface (disintegration) (7 eyes). More than 1 pattern was found in 4 specimens. The thickness of corneal epithelium varied between 13.4 and 102.6 microm, and the thickness of AM between 9.0 and 162.5 microm.

Conclusions: Amniotic membrane can integrate into the host corneal tissue after AMT in intraepithelial, subepithelial, or intrastromal patterns, or may be localized on the corneal surface. The thicknesses of corneal epithelium and AM are extremely variable. The morphology of the individual pattern seems to depend on the ocular surface disorder and AMT technique. Classification of AM integration patterns may assist in selecting the most suitable transplantation technique for specific surface disorders.