Long-Term Changes in Photocoagulation Burns1

: 101 argon laser and xenon arc photocoagulation burns were studied clinically and histopathologically in 8 diabetics patients treated for PDR. The age of the lesions ranged between 4 and 70 months. Our observations confirmed long-term patterns of retinal pair observed previously only in animals. Moderately severe burns, when placed in the thick paracentral retina, at times resulted in differentiated retinal repair not associated with new retinal adhesions. Severe burns created full thickness retinal defects, but spared the inner limiting membrane and allowed formation of apparently firm new retinal adhesions. These burns are considered as most suitable for the scatter treatment of PDR. Very severe burns exhausted the retinal capacity for glial repair so that the RPE became the only resource of retinal reparative tissue. In such scars the RPE bordered the vitreoretinal juncture yet did not invade the vitreous. However, glial preretinal membranes were frequently seen over very severe burns exerting tangential retinal traction.