The Effect of Lyophilization on Light Transmission of Amniotic Membrane: A Comparison with Rabbit Cornea

Amniotic membrane persists for a long time after ocular transplantation (as corneal substitute) and can affect light transmission (transparency). The aim of this study was to evaluate the transparency of amniotic membrane after freeze-drying (lyophilization) and to compare the results with transparency of rabbit cornea.
Transparency of rabbits’ corneas and fresh and lyophilized AMs from disk and peripheral (out of disk) regions of placenta were measured. The epithelial cells which have stem cell properties were removed with enzymatic digestion. The structure of amniotic membrane was evaluated using H&E, periodic acid-schiff and masson’s trichrome staining, and ultrastructural evaluation of surface was carried out using scanning electron microscope.
The transparency of lyophilized amniotic membrane was not different with that of fresh one. The light transmission of amniotic membrane from disk region was less than peripheral region. Removing of the epithelial layer improved the light transmission of the amniotic membrane up to the transparency of rabbit cornea. Scanning electron microscopy revealed that the epithelial cell remnants scatter the light after lyophilization.
Based on the results of this study, it is recommended to remove the epithelial layer of the amniotic membrane before lyophilization to increase its transparency amniotic membrane for corneal transplantation and ocular tissue engineering.