Thygeson lecture. Amniotic membrane transplantation: why is it effective?

To review the uses and previously proposed mechanisms of action of amniotic membrane transplantation (AMT) and to suggest a new mechanism of action for the effectiveness of AMT in resolving a persistent epithelial defect (PED).

Significant clinical and experimental publications are reviewed.

Evidence from the scientific literature suggests a new hypothesis for the effectiveness of AMT in the reepithelialization of a PED and the reduction of corneal stromal inflammation and continued fibrosis.

It is suggested that reepithelialization of a PED, and hence the reduction of stromal inflammation and continued fibrosis following reepithelialization, is aided by the combination of oxygenation, moisture and protection of the fragile epithelium by the amniotic membrane.