Amniotic membrane transplantation - analysis of structural characteristics in amniotic membrane transplant and corneal ulcers

Abstract

AIM: To analyze the structural characteristics in the cornea and the amniotic membrane (AM) with the help of laser scanning in-vivo confocal microscopy (IVCM) and to evaluate the morphometric changes in the cornea and the integration pattern of amniotic membrane into the host tissue using anterior-segment optical coherence tomography (AS-OCT) in patients with persistent corneal defect treated with amniotic membrane transplantation (AMT). MATERIALS AND METHODS: Nine eyes of six consecutive patients (mean age 44.9 ± 8.7 years) with corneal defects and stromal thinning unresponsive to topical treatment were enrolled in this study. Transplantation of cryopreserved amniotic membrane was performed. The time of healing of the corneal defect, morphometric analysis of the cornea and transplanted amniotic membrane using AS-OCT and the structural characteristics in the amniotic membrane grafts and corneal ulcers assessed by in vivo confocal microscopy were evaluated. RESULTS: Successful results after amniotic membrane transplantation (AMT) were observed in 8 of the 9 eyes (91.2%). On the 2nd day after transplantation, IVCM showed that under the amniotic membrane a new epithelium with large, flat, immature cells of the superficial corneal epithelium with an average density of 598.4 ± 66.38cells/mm2 was observed. The basal cells also showed immaturity and their average density was 1804 ± 93.32cells/mm2. In the corneal stroma edema and activated corneal cells were visualized. The average corneal epithelium thickness increased to 24.60 ± 2.07μm, the average density of epithelial cells increased to 657.6 ± 78.41cells/mm2, while the mean basal epithelium cells density was 2541 ± 540.13 cells/mm2. AS-OCT showed that the preoperative corneal thickness at the ulcer was 418.91 ± 96.56 μm. On the 2nd day after the surgery, the amniotic membrane (AM) thickness was measured to be 268 ±105 μm. On the 8th day it was two times smaller and was measured to be 123 ±39 μm. On the 25th day post-surgery the corneal thickness was measured at 494.03 ± 67.35 μm. In two of the cases integration of AM was found. CONCLUSIONS: AMT leads to recovery of corneal defects unresponsive to conservative treatment. The amniotic membrane graft is effective in promoting re-epithelization, nonetheless, it can also integrate into the host corneal tissue which results in an increase in corneal thickness, stabilization of the epithelium and reduction of the subjective signs. The integration of amniotic membrane into the damaged cornea proves that AMT is an effective and irreplaceable procedure for difficult-to-treat anterior ocular surface diseases.