Three women have been left blinded after taking part in a US clinic trial of an unproven stem cell treatment, according to a report in The New England Journal of Medicine.

Following the treatment, the women, who are aged from 72-88, are said to have suffered from vision loss, detached retinas and bleeding. They were all diagnosed with macular generation prior to the trial.

Fat tissue was removed from the patients’ abdomens with enzymes to obtain stem cells, which was then mixed with blood plasma and injected into the women’s eyes.

Both eyes were treated at the same time, which is an uncommon practice in clinical trials.

Experts investigating the case said the study failed to meet basic requirements of a properly conducted clinical trial.