Three patients went blind after receiving an experimental stem cell treatment for a common degenerative eye disease from a Florida company that proceeded without FDA approval, according to a March 15 report in a leading medical journal.

The report, Vision Loss after Intravitreal Injection of Autologous “Stem Cells” for AMD [age-related macular degeneration], appears in the New England Journal of Medicine. The authors said the cases serve as a cautionary tale about the perils of treatments involving unregulated, unproven therapies.

Before the procedure, one of the co-authors...