Researchers find new way to treat diabetic blindness

While levels of VEGF tended to be higher in those with proliferative diabetic retinopathy, some of their fluid had less VEGF than did the healthy participants.

But even the low-VEGF fluid from patients with proliferative diabetic retinopathy stimulated blood vessel growth in lab-grown cells.

"The results suggested to us that although VEFG clearly plays an important role in blood vessel growth, it's not the only factor, " Sodhi said in a statement.

A series of experiments in lab-grown human cells and mice revealed a second culprit, a protein called angiopoietin-like 4.

When the researchers blocked the action of both VEGF and angiopoietin-like 4 in fluid from the eyes of people with proliferative diabetic retinopathy, it markedly reduced blood vessel growth in lab-grown cells.

Sodhi suggested if a drug can be found that safely blocks the second protein's action in patients' eyes, it might be combined with the anti-VEGF drugs to prevent many cases of proliferative diabetic retinopathy.

The team is now investigating whether angiopoietin-like 4 might also play a role in other eye diseases, such as macular degeneration, which destroys the central portion of the retina.