Argon lasers provide photocoagulation at a wavelength and size in which it is possible to treat discrete vessels in the retina or vitreous. Therefore, it is possible to change the hemodynamics of the retina in an attempt to prevent the disabling complications of diabetic retinopathy. Diabetic macular edema may be treated by diminishing arteriolar flow to the edematous area. Proliferative retinopathy can be treated by total closure of the vessels feeding the proliferation.
Behrendt T. Therapeutic Vascular Occlusions in Diabetic RetinopathyArgon Laser Photocoagulation. Arch Ophthalmol. 1972;87(6):629-633. doi:10.1001/archopht.1972.01000020631003