[How effective is photocoagulation? (author's transl)]

Six hypotheses relating to the mode of action of photocoagulation, based on comprehensive data gathered from the literature, are put forward and discussed. Particular emphasis is given to the question of achieving a lasting break through of the barrier represented by Bruch's membrane and the pigment epithelium and thus to the altered diffusion conditions between the choriocapillaries and the retina. In addition a peculiar marginal fluorescence in fluorescein serial angiograms of old light coagulation foci is described and compared with data from the literature. The authors put forward a new hypothesis concerning the mode of action of light coagulation; they believe that particularly in the marginal areas affected by photocoagulation, completely new conditions are created for the metabolic exchange between choroid and retina, including the formation of anastomoses and shunts.