[Analysis of the progressive phases of diabetic retinopathy. Prevention and treatment by photocoagulation (author's transl)].

An attempt has been made to clarify various unresolved problems concerning the pathogenesis, course and treatment of diabetic retinopathy (d.r.) on the basis of an analysis of 2320 fluorescein angiograms performed on 150 patients at intervals of 1 week to 6 months during the period January 1967 to April 1975. The characteristic changes of diabetic angiopathy are already visible in the angiogram before the ophthalmoscopic and biomicroscopic features of d.r. become manifest (preretinopathic stage). Like in the later stages of d.r., hyperpermeability of the retinal capillaries predominates in certain patients, whilst stenosis and obstruction of the precapillaries and arterioles prevail in the remaining patients. Hyperpermeability frequently causes a decrease in, or a failure of perfusion of the retinal capillaries due to compression by the swollen perivascular tissue. D.r. is characterised by phasic development. In cases of primary exudative angiopathy an increase in the capillary hyperpermeability can precede phases of progression. Cases of primary occlusive angiopathy display a jerky type of involvement of larger and larger retinal vessels. An additional exudative component accelerates progression of the angiopathy. Large zones without visible capillaries or multiple small areas with deficient capillarisation, IRMAs and shunt vessels herald the imminent onset of the proliferative stage (preproliferative stage). The primary exudative types show slow evolution, whilst the primary occlusive types show rapid, phasic progression...