Clinicopathologic correlation of xenon arc and argon laser photocoagulation. Procedure in human diabetic eyes

Xenon arc and argon laser lesions applied as scatter treatment to two diabetic patients were studied clinically and histopathologically. Seventy-one burns were grouped as very severe, severe, and moderately severe, according to pigmentation and diameter of the retinal scar. All lesions except half of the moderately severe ones showed full-thickness retinal involvement. In very severe xenon burns, whether xenon or argon, only proliferated retinal pigment epithelium provided a thin retinal scar, corresponding to an ophthalmoscopic appearance of "bare sclera". In the center of severe and moderately severe lesions, both glial cells and pigment epithelium bridged the retinal defect, forming a thick pigmented scar that contained pigment-laden macrophages. Rephotocoagulation over such thick scars may be less hazardous than is generally assumed. Nonvascular preretinal membranes were frequently present over very severe xenon lesions but rarely over very severe argon burns.