Seven U.S.-based researchers are sharing a €1 million ($1.3 million) prize from a Portuguese foundation for their work developing treatment for angiogenic diseases of the retina, the leading cause of blindness in the developed world.

The recipients, announced Wednesday, included six researchers from Harvard Medical School and one from the University of California, San Diego School of Medicine.

Angiogensis refers to the growth of new blood vessels which can help spread cancer, and the prize aims to finance further research in the field.

The Lisbon-based Champalimaud Foundation's annual Vision Award was created in 2007. It claims to be the biggest cash award for work on eyesight and one of the world's largest scientific prizes.