Structural analysis of amniotic membrane for use in ophthalmology with different preservation techniques

PURPOSE: To evaluate structural differences in amniotic membrane fragments subjected to different preservation techniques for potential ophthalmologic applications. METHODS: Three placentas were collected from healthy donors, and four amniotic membrane fragments were prepared from each placenta. The fragments were divided into four groups with three samples each: cryopreserved, lyophilized, vacuum--dried using a vacuum concentrator, and fresh (control). After processing, the fragments were fixed, sectioned, and analyzed using scanning transmission electron microscopy to assess tissue morphology. RESULTS: All samples met the established evaluation criteria. No morphological differences were observed among the groups. The structural characteristics of lyophilized and vacuum-dried membranes were comparable with those of cryopreserved and fresh membranes. However, vacuum drying demonstrated the greatest practicality for ophthalmologic use, as it allows membrane availability at any time and storage at room temperature. CONCLUSION: Vacuum drying using a vacuum concentrator, lyophilization, and cryopreservation preserve the morphological characteristics of the human amniotic membrane similar to those of fresh tissue. A standardized protocol using a vacuum concentrator may be established owing to its advantages in storage convenience and accessibility.