Diabetic Retinopathy

Diabetic retinopathy may develop in type 1 or type 2 diabetes. Even when blood glucose levels are tightly controlled throughout one's life, a significant number of people with diabetes will have some signs of diabetic retinopathy as they age (because diabetes weakens blood vessels). For patients with diabetes who do not adequately control their blood sugar levels, diabetic retinopathy may develop earlier.

Smoking also may make diabetic retinopathy worse. Smoking and the effects of nicotine constrict blood vessels throughout the body. For people with diabetic retinopathy, smoking can harm already weakened blood vessels in the eyes.

Unfortunately, diabetic retinopathy has no early symptoms. It is only later, when retinopathy has progressed, that people with diabetes will begin to notice impaired vision. Other symptoms at this stage include:

• Blurred vision
• Inability to focus the eyes when reading
• Floaters in the eye
• Pain in the eye
• Partial or total loss of vision 

Diabetic retinopathy is diagnosed with a slit-lamp exam that allows your ophthalmologist or optometrist to view the internal structures of your eyes, including the retina. Your eye doctor can see the early beginnings of diabetic retinopathy with this exam. Because diabetic retinopathy has no early symptoms, it is important that all patients with diabetes have annual eye exams.

Diabetic retinopathy is classified into four stages:

• Mild nonproliferative retinopathy—This is the earliest stage of diabetic retinopathy, during which your eye doctor may see swelling developing in tiny blood vessels in the retina.
  
• Moderate nonproliferative retinopathy—At this stage, your eye doctor may see blockage of some of the blood vessels that nourish the retina.
  
• Severe nonproliferative retinopathy—Your eye doctor may see many more blood vessels blocked and the beginnings of new, smaller blood vessels growing on the retina. Because the blood vessels are blocked, the body will grow new blood vessels to nourish the retina.
  
• Proliferative retinopathy—During this later stage of development, your eye doctor will see many new, smaller and quite fragile blood vessels growing on the retina and into the vitreous gel inside the white portion of the eye. These smaller blood vessels can burst and leak blood onto the retina, significantly impairing vision. Patients with this stage of diabetic retinopathy are also at high risk of developing macular edema—swelling of the macula, which is the center of the retina where focused vision occurs.
   
  Over time, ruptured blood vessels can form scar tissue on the retina that can cause the retinal layers to pull away from each other and from the wall of the inner eye (retinal tear/detachment). This irreversible condition results in severe vision loss or blindness.

The first goal of treatment is to ensure that diabetes (blood glucose levels) is under control with appropriate medications. Laser therapy to cauterize or seal leaking blood vessels is standard treatment in patients with proliferative retinopathy to prevent the condition from progressing and further damaging the retina.

• Laser surgery
  During this procedure, called panretinal photocoagulation treatment, a laser is aimed at the retina—but away from the central macula— and one- to two-thousand laser exposures are applied to the retina, which stops the growth of blood from the retina. This outpatient procedure is performed in the Section of Ophthalmology. Two or more sessions may be required to complete treatment. Before the procedure begins, the eye is dilated and anesthetic drops are applied. While laser surgery helps to control the loss of eyesight, it may produce a loss of side vision, color vision and night vision.
  
• Vitrectomy
  Normally, blood vessels do not grow within the vitreous gel—a liquid substance within the eye that helps retain the shape of the eye. The growth of blood vessels within this area, and hemorrhaging of blood, is seen as a late-stage development in patients with diabetic retinopathy. Left untreated, the condition can severely affect vision, damage the retina and cause blindness.
   
  A vitrectomy procedure removes the vitreous gel—and the leaking blood vessels—and replaces it with a clear saline solution. This procedure is performed in the operating room. After you have a local or general anesthetic, your ophthalmologist will make small incisions in the sclera, the white part of the eye. He or she will then use microsurgical instruments to enter the eye and remove the vitreous gel, and replace it with a saline solution. The procedure may take an hour or longer, depending upon whether your surgeon also repairs a retinal detachment and performs cataract surgery.
   
  Following surgery, you will wear an eye patch and—depending upon the extent of your treatment—will need to rest for several days to give your eye time to heal. 
  
• Treatment for macular edema
  Macular edema occurs when hemorrhaging of blood from blood vessels on the retina causes the macula, the center of vision at the center of the retina, to swell. This serious condition is treated with focal laser therapy, during which laser applications are applied to the retina, around the area of the macula, which helps reduce the amount of leakage from blood vessels. Focal laser therapy is standard treatment for this condition and has good results in the majority of patients. Some patients also may require treatment with a medication to help reduce intraocular swelling.