What You Should Know About Diabetic Retinopathy

What is diabetes?

Diabetes mellitus is a disease causing the blood sugar (glucose) to become elevated. There are two basic kinds of diabetes. Type 1 diabetes is diagnosed early in life and requires insulin to bring the glucose level down to normal. Type 2 diabetes occurs later in life, and can be controlled with diet, pills, or insulin, depending on its severity. Approximately 18 million Americans have diabetes, with over one-third of those affected being undiagnosed.

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How does diabetes affect the eye?

dme Diabetes primarily affects the blood vessels that nourish the retina. The retinal vessels work like a garden hose, bringing oxygen and other nutrients into and out of the eye. Diabetes causes them to sprout tiny leaks, or microaneurysms (non-proliferative diabetic retinopathy), which makes the surrounding retina swell and not work properly. Central vision can become blurred, just as a water droplet placed on a photograph will cause the picture to blister and become distorted (diabetic macular edema).

oct
dme_oct
OCT scan (top) of normal macula compared to OCT image
of diabetic macular edema (bottom).

pdr Diabetes can also make the blood vessels close off. Some eyes will develop tiny new blood vessels in an attempt to increase the retinal blood supply (proliferative diabetic retinopathy). These new vessels do not help the eye, however. They are fragile and can cause blindness by hemorrhaging or retinal detachment.

Who gets diabetic retinopathy?

Diabetic retinopathy develops gradually over many years. People with Type I diabetes, those requiring insulin to control their blood sugar, and patients with diabetes for many years are at an increased risk for developing retinal problems. Poor control of the blood glucose, pregnancy, uncontrolled high blood pressure, and smoking also aggravate diabetic retinopathy.

Approximately 50% of diabetics (about 5 million Americans) will develop some form of diabetic retinopathy. Diabetic retinopathy is the leading cause of vision loss and new-onset blindnesss in the United States in those 20 to 74 years of age, with new cases of blindness developing in 12,000 to 24,000 persons annually. Remarkably, much of this vision loss is preventable with more timely diagnosis and treatment.

How is diabetic retinopathy diagnosed?

You can't diagnose diabetic retinopathy by looking in the mirror since your eye will usually look and feel normal. Vision is also often normal despite the presence of potentially blinding eye conditions. Only a thorough retinal examination through a dilated pupil can detect these problems. Properly timed treatment can often stabilize vision although it is less likely to improve it. The key to maintaining good eyesight, therefore, is early diagnosis and treatment before symptoms occur. Most diabetic patients need dilated eye examinations at least once a year throughout their lifetime. Further testing, including photography, fluorescein angiography, and OCT scanning may be done to assist in the diagnosis and treatment of any changes thought to cause visual loss.

normalvision diabetesvision
Normal Vision. Diabetic Retinopathy.

What treatments are available for diabetic retinopathy?

  1. Medical.

    Good control of your blood sugar can significantly decrease the chances of diabetic retinopathy developing or progressing. However, there are some people who, despite eating right and controlling their diabetes as best as possible, will still get significant eye disease.

  2. Laser surgery.
    1. Introduction.

      retinal laserLaser photocoagulation is one of the main ways that diabetic retinopathy is treated. A laser is an instrument that produces a pure, high-intensity beam of light energy. The laser light can be focused onto the retina, selectively treating the desired area while leaving the surrounding tissues untouched. The absorbed energy heats, or photocoagulates, the retina, creating a microscopic spot.

      Laser surgery is performed in our office while you are awake and comfortable. The laser treatment usually takes less than 30 minutes to complete and you can go home immediately following surgery. Arrangements for transportation should be made in advance since you may not be able to drive right away.

      It will take several weeks to months before we can tell whether the laser surgery has been successful. Since diabetes is a progressive disease, many patients need more than one treatment to control their eye problem and prevent further loss of vision.

    2. Macular edema.

      The laser is used to seal the leaking vessels causing macular edema (focal or grid photocoagulation). In the Early Treatment Diabetic Retinopathy Study, photocoagulation decreased the risks of persistent macular edema and significant visual loss by about 50%, regardless of the baseline vision. Significant visual loss occurred in 5% of treated eyes compared to 8% of untreated eyes at 1 year, 7% of treated eyes compared to 16% of untreated eyes at 2 years, and 12% of treated eyes compared to 24% of untreated eyes at 3 years of follow-up. Photocoagulation was shown not to be of benefit for eyes without clinically significant macular edema, as the risk of significant visual loss with or without treatment was small.Photocoagulation did not significantly improve vision.

      prelasercsme postopcsme
      Central diabetic macular edema with yellow,
      fatty lipid threatening the macular center.
      Excellent response following laser
      photocoagulation.
    3. Proliferative diabetic retinopathy.
      pdrprp New vessels in eyes with proliferative retinopathy can often be made to disappear with panretinal photocoagulation. Microscopic laser spots, placed into the peripheral retina, improve retinal circulation causing neovascularization to disappear.
      Panretinal photocoagulation consists of
      yellowlaser spots placed outside the
      optic nerve and macula .

      In the Diabetic Retinopathy Study, the overall risk of severe visual loss with proliferative diabetic retinopathy at the 2-year follow-up examination was 16% in the control eyes compared to 6% in the treated eyes. With Diabetic Retinopathy Study high-risk characteristics, this risk increased to 26% of the control eyes and 11% of the treated eyes.

      prelasernvd postlasernvd
      Lacy new blood vessels (disc
      neovascularization) are seen (arrow)
      overlying the optic nerve.
      The new vessels resolved following
      panretinal photocoagulation.
  3. Intraocular steroids and Anti-VEGF agents.

    Intraocular steroids and VEGF inhibitors (Avastin, Lucentis), which have become the mainstay treatment for macular degeneration, also appear to rapidly stabilize diabetic vascular endothelial leakage and have become another tool for treating diabetic macular edema. Unlike laser photocoagulation, vision often improves significantly. The most commonly used steroid is triamcinolone, which is effective for up to six months per injection. Lucentis and Avastin are effective for up to several months. Common steroid side-effects include elevated intraocular pressure and cataract.

    The DRCR.net, in a large multicenter study, surprisingly found that over a 2-year period, laser photocoagulation was more effective with fewer side effects than intravitreal triamcinolone. The value of combination treatment (initial intraocular steroid of VEGF inhibitor to quickly improve vision and macular edema followed by laser photocoagulation for long-term control) or VEGF inhibitor monotherapy remains to be determined.

  4. Vitrectomy surgery.

    Some patients with severe proliferative retinopathy will develop extensive bleeding or retinal detachment that can cause blindness. Vitrectomy surgery is done at the hospital, usually on an outpatient basis. These advanced microsurgical techniques often allow us to restore vision by removing the hemorrhage and bleeding tissues. Vitrectomy is also used for some eyes with macular edema that fail to respond to laser photocoagulation or intraocular steroids.

    preppv postppv
    Yellowish neovascular tissue is
    detaching the macula.
    The retina reattached following
    vitrectomy surgery.
     
    Observe vitrectomy surgery where vitreous blood in
    a patient with diabetes is removed.
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