Overall, vision loss from diabetes may occur from several causes. Elevated blood sugar overtime will damage cells that line the blood vessels in the retina. This creates tiny aneurysms that leak fluid into the retina causing retinal edema. If the swelling involves the area in the retina where we focus to read, called the macula, (Diabetic Macular Edema), the vision may get very blurry
Laser treatment to shut down leaky aneurysms has been the mainstay of treatment. This is called Focal or Grid Laser treatment. Large studies have shown a lower incidence of vision loss with laser treatments. If diabetic macular edema is suspected, special testing of the macula may be done to look for leaking blood vessels. A fluorescein angiogram is a series of photos taken after a special vegetable dye is injected into your arm. Other medical therapies for diabetic macular edema are evolving specifically targeting the blood vessels leaking at the cellular level.
Diabetes may also cause abnormal blood vessels to grow on the surface of the retina. This is called Proliferative Diabetic Retinopathy or PDR. These new blood vessels can cause vision loss by bleeding into the center of the eye (the vitreous) or by scarring the retina. These abnormal blood vessels are treated with a pattern of hundreds of laser burns in the peripheral retina. This is called panretinal photocoagulation or PRP. PRP allows the abnormal blood vessels to shrink, and then the body can reabsorb any blood that has leaked. Studies have shown PRP laser treatment reduced severe vision loss by 50%.
A vitrectomy is sometimes required if the blood does not reabsorb on its own or if scar tissue threatens the vision following PRP. The vitreous is a jelly-like material in the central cavity of the eye. Comparatively, a vitrectomy removes the vitreous and the non-clearing blood and replaces it with a clear salt solution. Scar tissue on the retina may also be removed at the time of a vitrectomy.