The effect of photocoagulation on the choroidal vasculature and retinal oxygen tension.

Light microscopy and latex-pigment injection of rhesus monkey eyes studied at varying times after retinal laser and xenon photocoagulation of varying intensity showed that the choriocapillaris was obliterated by a wide range of intensities but that the choroidal arteries and veins remained open. Retinal oxygen tensions acutely increased over the lesion but later subsided to normal. Multiple treatment sessions several days apart may reduce the risk of hemorrhage associated with hypermia secondary to photocoagulation.