Diabetic Retinopathy

One of the potential complications of diabetes affects one or both eyes. Called diabetic retinopathy, the retina blood vessels are damaged causing vision problems. The damage is often due to long term blood pressure causing swelling of the blood vessels or abnormal blood vessel growth, and to stress placed on blood vessels due to fluctuating blood glucose levels.

What is Diabetic Retinopathy?

The eye is an elaborate sensory organ working with the brain to make vision possible. It consists of 3 major layers: the outer coat made up of the cornea and sclera, the middle vascular coat (uveal tract) and the inner nervous coat. It also consists of 3 chambers. These are the anterior and posterior chambers and the vitreous cavity. The inner surface coat of the eye is called the retina. It is distinctly red in color (which is why we have red-eye recution on cameras), and coats only the back half of the eye.

The retina carries the receptor endings for light. These signals are transmitted to the brain through the optic nerve. The brain interprets the signals, translating them into the pictures we “see.” All of this requires blood vessels to nourish and support the nerve and brain function.

Retinopathy is a disease that affects the retina. It affects those with type 1 (T1D) and type 2 diabetes (T2D) and progresses in stages. Over time it decreases your ability to see and can eventually result in loss of vision. This may be partial or total vision loss. In fact, diabetic retinopathy is the leading cause of adult blindness.

Stages of Retinopathy

There are 3 basic stages of retinopathy. They are:[1]

  1. Mild nonproliferative or background retinopathy – This is the first stage. There is little overt indication that potential eye problems are developing. Only a doctor can see small bumps on the blood vessels of the eye called microaneurysms[2]
  2. Moderate nonproliferative or pre-proliferative retinopathy – The result of deteriorating blood flow into the retina with symptoms including multiple hemorrhages as well as small amounts of bleeding. The potential for vision loss is there but not yet manifested.
  3. Severe nonproliferative retinopathy – This is a progressive stage in which more blood vessels become blocked. This deprives several regions of the retina of blood supply. As a result, the body gets signals to develop more blood vessels.
  4. Proliferative Retinopathy – New blood vessels grow, but are thin and prone to bleeding. A scar may form. The result is impaired vision or blindness.

The stages of retinopathy are progressive but may be reparable if caught in time. Vision loss is usually due one of two conditions:

  • Macular edema – fluid leaks into the macula where sharp vision is found causing blurred vision
  • Proliferative Retinopathy – the fragile new blood vessels leak blood into the eye causing blurred vision or blindness

Signs and Progression

A big problem with retinopathy is that there is often a lack of early visible signs or symptoms that it exists until vision is affected. It may strike the diabetic with no warning. You may awake one morning to find vision is blurred in one eye. There is no accompanying pain and the problem may resolve itself temporarily. The lack of vision may then reappear days or weeks later. This time, however, the same eye or another is affected by more severe loss of vision as the complication progresses.

Prevalence and Risk

In the United States, if you are diabetic and under the age of 60, you are certainly at a high risk of experiencing blurred vision or becoming blind from diabetic retinopathy. If you have T1D for more than 20 years, you will probably join the 99% that have retinopathy. Of this group 53% will progress to the proliferative or most severe stage. In T2D, the statistics for those with diabetes for at least 20 years show 60% develop retinopathy and 5% progress to the proliferative stage.[3]

Those who are at risk of this disease are:[4]

  • Individuals who have been diabetic for a period of time
  • Pregnant women
  • Those who have poor glycemic control
  • African-Americans and Hispanics
  • Diabetic with hypertension
  • Diabetic with renal disease

Discovering Retinopathy

The most common method of detection of retinopathy is by a doctor’s examination. A routine eye examination can detect changes in the retina’s blood vessels. Tests include a visual acuity test and, sometimes, dilated eye test. If you have any doubts about the health of your eyes and talk to your eye doctor, he or she may employ more sophisticated techniques to search for any indications of retinopathy. The tests will also be able to help the doctor evaluate the full extent of the problem.[5] Several agencys, to include the American Diabetic Association, recommend that patients with diabetes get annual eye exams to screen for these problems.

Specific technology may be helpful in determining what exactly is occurring behind your external eye.  Technology has been particularly useful in the Digital Retinal Screening Program – a systemic program set up to help a diabetic detect any early indications of retinopathy.

Among the tools that can be used is optical coherence tomography equipment. The device is very similar to an ultrasound. It is able to make out the thickness of the layers of the retina. It can also discover if there has been or is any current abnormal swelling. If your doctor suspects leaking vessels, he or she can expose them by injecting a dye into the arm. This dye will then appear in the leak occurring in the retinal blood vessel.

Treatment

Treatment for diabetic retinopathy is based upon the stage of the disease. During the stages prior to proliferation, it is necessary to get your diabetes under control. If proliferative retinopathy exists, you will require scatter laser treatment on your eyes to minimize the obstruction caused by the abnormal blood vessels. More serious disease symptoms, such as bleeding, may require a vitrectomy. In this procedure, the doctor removes blood from the normal fluid in your eye.

Conclusion

Diabetic retinopathy is common in those who have diabetes, and particularly in those who have had it for a long period of time. It affects those with T1D and T2D. Retinopathy progresses through various stages unless it is caught in time. It is usually detected after an episode in which the individual has lost vision temporarily or during a routine eye examination. In either case, the underlying cause is poor management of diabetes.

While diabetic retinopathy may not be completely escapable for some, it can be treated and delayed. It is essential, if you want to avoid this complication of diabetes, that you manage your diabetes effectively.

References

[1] American Diabetes Association (2009). Type 2 Diabetes. Your Healthy Living Guide. Alexandria, VA: ADA.

[2] Meltzer, SJ; and Belton, AB (2009). Diabetes in Adults. Toronto: Key Porter Books.

[3] David J. Browning, DJ (2010) “Diabetic Macular Edema” in Diabetic Retinopathy Browning, DJ (ed). New York: Springer, p 141-202.

[4] E. Bowie, E; and Crosson, CE (2009). “Diabetic Retinopathy” in Handbook Of Neurochemistry And Molecular Neurobiology, Lajtha, A (Ed). New York: Springer pp:165-177.

[5] Levin, ME; and Pfeiffer, MA (editors) (2009). The Uncomplicated Guide to Diabetes Complications, 3rd ed. Alexandria, VA: ADA.

[6] This article was originally published July 12, 2012 and last revision and update of it was 9/10/2015.