Diabetic retinopathy (pronounced ret in OP uh thee) is a complication of diabetes that causes damage to the blood vessels of the retina— the light-sensitive tissue that lines the back part of the eye, allowing you to see fine detail.
Diabetic retinopathy is the most common cause of irreversible blindness in working-age Americans. As many people with type 1 diabetes suffer blindness as those with the more common type 2 disease. Diabetic retinopathy occurs in more than half of the people who develop diabetes.
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It is possible to have diabetic retinopathy for a long time without noticing symptoms until substantial damage has occurred. Symptoms of diabetic retinopathy may occur in one or both eyes.
Symptoms may include:
- Blurred or double vision
- Difficulty reading
- The appearance of spots— commonly called “floaters”— in your vision
- A shadow across the field of vision
- Eye pain or pressure
- Difficulty with color perception
The primary cause of diabetic retinopathy is diabetes—a condition in which the levels of glucose (sugar) in the blood are too high. Elevated sugar levels from diabetes can damage the small blood vessels that nourish the retina and may, in some cases, block them completely.
When damaged blood vessels leak fluid into the retina it results in a condition known as diabetic macular edema which causes swelling in the center part of the eye (macula) that provides the sharp vision needed for reading and recognizing faces.
Prolonged damage to the small blood vessels in the retina results in poor circulation to the retina and macula prompting the development of growth factors that cause new abnormal blood vessels (neovascularization) and scar tissue to grow on the surface of the retina. This stage of the disease is known as proliferative diabetic retinopathy (PDR).
New vessels may bleed into the middle of the eye, cause scar tissue formation, pull on the retina, cause retinal detachment, or may cause high pressure and pain if the blood vessels grow on the iris, clogging the drainage system of the eye—all of this can cause vision loss.
This particular retinal disease is most common in those that are 60 years or older, as well as female.
Age is the primary risk factor for the development of macular pucker. Additional risk factors include a history of a retinal tear or detachment, diabetes, retinal venous occlusions, and inflammation in the eye (called uveitis).
The best way to diagnose diabetic retinopathy is a dilated eye exam. During this exam, the physician places drops in the eyes to make the pupils dilate (open widely) to allow a better view of the inside of the eye, especially the retinal tissue.
Figure 1. OCT of a patient with bilateral proliferative diabetic retinopathy with diabetic macular edema in the left eye. ©ASRS Retina Image Bank, May 2016. Image 26525. Olivia Rainey, Retina Specialists of Michigan.
The physician will look for:
- Swelling in the retina that threatens vision (diabetic macular edema)
- Evidence of poor retina blood vessel circulation (retinal ischemia— pronounced iss KEY me uh)
- Abnormal blood vessels that may predict an increased risk of developing new blood vessels
- New blood vessels or scar tissue on the surface of the retina (proliferative diabetic retinopathy)
Regular dilated eye exams by an ophthalmologist are important, especially for those who are at a higher risk for diabetic retinopathy or diabetes. If you are over age 50, an exam every 1 to 2 years is a good idea so the physician can look for signs of diabetes or diabetic retinopathy before any vision loss has occurred.
In addition to checking for signs of diabetic eye disease, a comprehensive dilated eye exam will evaluate your vision/need for corrective lenses, eye pressure (looking for glaucoma), the “front” of the eye (eyelids, cornea, checking for dry eye), lens (looking for cataracts), as well as a complete exam of the retina and vitreous.
In addition to this exam, physicians use other tests to detect and manage diabetic retinopathy:
An optical coherence tomography (OCT) test provides highly detailed cross-sectional images of the retina that show its thickness, helping determine whether fluid has leaked into retinal tissue.
The physician may take fundus photographs of the back of the eye to help detect and document diabetic retinopathy. These photos make it easier for the physician to monitor the disease on follow-up visits to determine if it is worsening.
To evaluate retina blood vessel circulation, the physician may conduct a retinal photography test called fluorescein angiography (FA). After dilating the pupils, the physician will inject a dye into the patient’s arm. The dye then circulates through the eyes and works like a food coloring; however, it does not affect the kidneys and is unlike the dye that is used with MRIs and CAT scans.
As the dye circulates, the physician takes pictures of the retina to accurately detect blood vessels that are closed, damaged, or leaking fluid. The pictures are black and white to help the doctor detect these changes more easily, but the process is not the same as having an x-ray. Prior to examination, ask your physician to discuss the risks and benefits of obtaining these images.
With proper examinations, diabetic retinopathy can be detected before vision loss begins. If the physician detects signs of diabetic retinopathy, she/ he will determine how frequently follow-up examinations will be required to detect changes that would require treatment.
Treatment and prognosis
Macular holes can be treated with a surgical procedure called a vitrectomy. During the procedure, the vitreous gel is removed and replaced with a bubble of gas and air. Over the course of a few days to weeks the bubble will help the macular hole “close”. Patients may be required to maintain a face-down position for a few days after surgery to help the gas bubble exert pressure on the hole and help it “close”. The gas bubble will gradually dissolve and leave the eye over a few weeks. It is important that patients with a gas bubble in their eye not fly or receive inhaled anesthetics during the brief time they have a gas bubble in their eye as it can result in the pressure in the eye elevating as the bubble expands. Smaller macular holes can, in rare instances, heal themselves.
Effectiveness of surgery is on a patient-to-patient basis; however, patients who had macular holes for shorter periods of time tend to heal faster than those who had macular holes for several months or years.
If a macular pucker is having no significant effect on your vision, the retina specialist may not recommend surgery and instead suggest follow-up visits to check your vision and repeat the OCT scan. If a macular pucker is severe and results in loss of vision or significant macular wrinkling, your doctor may recommend a vitrectomy and membrane peeling, where the vitreous gel is removed and the scar tissue is peeled from the surface of the retina.