Laser therapy has been the cornerstone of treatment for proliferative diabetic retinopathy and macular edema for over thirty years. Panretinal photocoagulation, developed at Joslin’s Beetham Eye Institute, has been a major breakthrough in preserving the vision of people with even advanced eye disease.
But research over the past few years also led by Joslin scientists has shown that a different type of therapy, one that uses a series of injections into the eye called anti-VEGF therapy, may not only preserve vision in those with macular edema but also actually improve their eye sight.
Macular edema is a common complication of diabetes. Almost all people with diabetes will show some evidence of retinopathy after 15-20 years of diabetes, and some will progress to the complication of diabetic macular edema.
Diabetic macular edema is a leaky blood vessel disease. Uncontrolled diabetes leads to dysfunction of the retinal vasculature in the eye. The retina is a light sensitive tissue at the back of the eye which acts in a way similar to the old style film in a camera.
When light hits it, chemical changes take place and signals are sent to the brain which processes them into the images we see. At the center of the retina is the region called the macula. The macula gives us our sharp, central vision which we use for driving, reading and recognizing people’s faces.
When diabetes causes the vascular network to break down, the blood cells become oxygen deprived. This stimulates the ocular tissues to produce a substance called vascular endothelial growth factor—VEGF for short.
VEGF triggers the body to make a new network of blood vessels. Unfortunately, the new network of blood cells is very fragile and break and leak easily. In addition, the VEGF can make existing blood vessels leaky. These leaky vessels allow fluid into the retina which pools in the macular, causing it to swell. Fatty deposits may also accumulate in the macula leading to further vision loss.
In the early phases there may be no symptoms. As the disease progresses, straight lines become crooked, and, blurry areas may appear in the center of vision. Over time this can lead to permanent reduction of central vision.
Diabetic macular edema has been treated with laser therapy for over 25 years, but this treatment destroys areas of retina in order to save vision.
Anti-VEGF treatment was pioneered by individuals at Joslin and elsewhere around the world. The benefit of this treatment was rigorously shown in 2011. Anti-VEGF therapy resulted in 3x less vision loss and 2x more vision gain than did laser alone. Although laser may need to be used in addition in some cases, the number of laser treatments was much reduced.
The actual procedure of injecting the antiVEGF therapy into the eye is very short, taking only a few minutes. First, eye drops dilate the eye and a small area of the surface of the eye is made numb. A needle is inserted into the eye and the injection given. Inserting the needle and giving the injection takes only a few seconds.. Although scary sounding, patients experience very little pain as the eye is well anesthetized. Vision may or may not be blurred for the rest of the day and sometimes drops are given for a few days after.
Will anti VEGF replace laser therapy as the treatment for macular edema or will both continue to be used? Only more research will tell. The 3 year results will be presented by Joslin researchers at a major meeting this year and may help us answer that question.
But this we know for certain—keeping your blood glucose and blood pressure and blood lipids in good control and seeing an ophthalmologist experienced in working with patients’ with diabetes on a regular basis can help you maintain your vision.