The argon laser is such an effective method of treating diabetic retinopathy that it is used in the early stages. The indications for treatment are related either to ophthalmoscopically visible lesion, or to lesions revealed by angiography, which is necessary each year in all diabetics. As for as technique goes, it is desirable to begin pan-retinal photocoagulation in the periphery so as to take advantage of the drying out of the related oedema secondary to the destruction of the retina.