Proliferative Diabetic Retinopathy (PDR) can be seen in the eye with an ophthalmoscope as neovascularization, a proliferative growth of abnormal new blood vessels. Neovascularization appears as a twisted collection of blood vessels and is quite dangerous because these vessels grow abnormally out of the retina into the clear vitreous gel. Because vessels grow beyond the supporting structure of the retina, they are very prone to bleeding, especially when they occur near the disc, the area where blood vessels and nerves enter the eye. Any jerking motion or even a rise in the blood pressure can lead to a rupture of one of these abnormal vessels and cause a hemorrhage.

Please click below for a brief but detailed animation.

Bleeding into the vitreous stops the transmission of light into the eye and may be noticed as red, grey, or black dots in the visual field. If bleeding is extensive, a rapid, painless blackening of vision occurs. Later, over a period of weeks, blood slowly clears from the vitreous cavity and vision returns. At that point, we can start to see the retina and use laser treatments to close off these dangerous blood vessels.

If extensive or repeated bleeding occurs, fibrous tissue or scarring can form on the retina. Since the retina is a thin structure made up of only a few layers of cells, scarring can easily pull or detach the retina. Retinal detachment may be noted as wavy lines or a curtain-like effect that appears in one area of vision. These wavy areas are not always obvious, but can sometimes be picked up by testing with an Amsler grid. Further loss of vision may occur if the retina is not reattached.

Before bleeding occurs, a patient who has neovascularization will usually not be aware they have these abnormal blood vessels. But they can be detected at an early stage with regular eye exams, and laser treatment at this stage will often prevent bleeding from occurring.

Pan-Retinal Photocoagulation

Pan-Retinal Photocoagulation (PRP) is a procedure where a laser is used to destroy all of the dead areas of retina where blood vessels have been closed. When these areas are treated with the laser, the retina stops manufacturing new blood vessels, and those that are already present tend to decrease or disappear. As these abnormal vessels disappear, the risk of vitreous hemorrhage and retinal detachment is reduced.

If there is leakage in the macula (Macular Edema), the central area of the retina where sharp vision takes place, Focal Macular Laser applications can also treat the specific areas in the central vision that are leaking. This treatment is very different from PRP. The power is much less, and fewer spots are needed. When both proliferative retinopathy and macular edema are present, and both focal macular laser and PRP are needed, the focal laser is usually done first when possible and the PRP several weeks later.

The goal of pan-retinal photocoagulation (PRP) is to prevent the development of new vessels over the retina and elsewhere, not to regain lost vision. At Woolfson Eye Institute (WEI), pan-retinal photocoagulation is an option for patients who have been diagnosed with proliferative retinopathy and where we have determined that pan-retinal photocoagulation is the appropriate treatment for their condition.