The larger retinal blood vessels are shown, in red and blue. In a type 1 patient after 14-25 years of diabetes new blood vessels grow before any leaks. The tiny 'new' blood vessels grow froward from the retina, as shown oppostie. Many thousands of laser burns may be necessary to stop the vessels growing. In a typical patient 6-8 laser sessions per eye may be needed, over three years.
Laser prevents the new vessels bleeding.
Without laser there is likely to be a lot of bleeding, and such people can eventually become blind. If a person needs a lot of laser driving, especially at night, may become difficult.