If the amount of new vessels is great, laser treatment can often prevent loss of vision. The type of laser treatment that is done when there are a lot of vessels is called Panretinal Photocoagulation. This type of laser treatment is usually done in two or more separate sessions. The idea is to use the laser to destroy all of the dead areas of the retina where the 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 diminish or disappear.
There are side effects of panretinal photocoagulation, and, for this reason, this treatment is not done when only a small amount of new vessels are present. It is important to remember, however, that when the amount is great enough to warrant laser treatment, the longer the eye remains untreated the more likely vision will be lost and blindness will occur. The earlier severe new vessels are discovered and the eye is treated, the more likely blindness can be prevented. If you have developed any of these abnormal new vessels, your doctor will help advise you about when panretinal photocoagulation should be done.
Panretinal photocoagulation does not improve vision; it is just a means of holding vision stable to prevent further loss. After laser treatments, patients may still have reduced vision or may continue to lose more vision. But if laser is indicated, the chance are that laser treatment will prevent severe loss of vision.
Panretinal photocoagulation is placed on the side of the retina, not the center, and side vision will definitely be diminished. These side areas are sacrificed in order to save as much of the central vision as possible and to save the eye itself. Night vision will also be diminished. After laser, blurred vision is very common. Usually this blur goes away but in a small number of patients, some blur will continue forever.