Amniotic membrane transplantation for the management of corneal epithelial defects: an in vivo confocal microscopic study

Purpose: To evaluate amniotic membrane (AM) tissue morphology and corneal epithelial healing in human eyes after amniotic membrane transplantation (AMT), using laser scanning in vivo confocal microscopy (IVCM). Patients and methods: Twenty eyes of 20 patients, treated with single layer epithelial side up AMT for chemical burns in the acute stage (n = 8) and persistent corneal epithelial defect (n = 12) were studied by serial IVCM post-AMT until complete re-epithelisation. Changes in morphology of transplanted amniotic tissue and healing corneal epithelium were noted. AM and corneal epithelial cell density was calculated using image-analysis software. Results: IVCM enabled visualisation of transplanted AM and of regenerating epithelial cells under the AM. The mean AM epithelial cell density, 1 day after transplant, was 4613 (SD 380) cells/mm2. The average AM epithelial thickness was 35 (4) μm, while the AM stromal thickness was 116 (31) μm. The amniotic stroma appeared to be composed of a superficial dense fibrous layer and a deeper loose reticular network of fibres. Amniotic epithelium was lost within 15 days of transplant, and complete re-epithelisation of the corneal surface was achieved between 1 and 4 weeks. Conclusions: Laser scanning IVCM is a useful method for evaluating AM tissue morphology, degradation and corneal epithelial healing after AMT for different clinical indications. When the amniotic membrane acts as a patch, that is epithelial cells migrate under rather than over the membrane, the membrane disintegrates and is lost.