Panretinal Photocoagulation (PRP) is a laser treatment directed towards unhealthy retina. Due to diminished blood supply by vascular diseases such as diabetes and vein occlusions, areas of the peripheral retina become deficient in oxygen (hypoxia or ischemia). The hypoxic retina then develops abnormal blood vessels which are fragile and often bleed, leading to vitreous hemorrhage. In addition, tractional retinal detachment, macular edema, and neovascular glaucoma may also occur secondary to ischemic retinopathy.
PRP is laser light applied to the peripheral retina. This ablates small spots of retina, decreasing its need for oxygen and reversing the ischemia. This reduces the inducement to grow new blood vessels and decreases the likelihood of hemorrhage or other vision threatening events.