Part three of our series on Vision and Diabetes explores the important topic of diabetic retinopathy.  It is important for people with diabetes to realize this condition is very common and that it can lead to vision loss and blindness. As much as 80 percent of people with type 1 diabetes will have diabetic retinopathy as they observe their 15th anniversary with the disease.  For people with type 2 diabetes, up to 84 percent will develop it after 19 years of diabetes.(1)  This blog will discuss 9 questions on diabetic retinopathy to help you learn about keeping your sight. Read both Part 1 – What is Glaucoma and 9 Facts About it, and Part 2 – What are Cataracts and 9 Related Questions, to learn about other potential problems that affect people with diabetes.   

what is diabetic retinopathy and 9 related questions from diabetescare.netQuestion 1: What is the function of the retina?
The retina is a thin layer of cells containing photoreceptors called rods and cones. The retina covers approximately 65 percent of the interior surface of the back of the eye.(2) Both rods and cones help to perceive light. Chemical reactions in rods help us see when there are low levels of light. Other reactions take place in cones which allow us to see color and detail. Chemical reactions in these cells cause impulses which, when transmitted to the brain through the optic nerve, are interpreted as light.(3) The macula is a part of the retina that is the size of a grain of rice.  Although very small this part is of the retina is densely populated with rods, is responsible for our central vision, most of our color vision as well as the fine details of our sight.(4) In the center of the macula is an area called the fovea that contains only cones.(5) 

Question 2: What is diabetic retinopathy?
Diabetic retinopathy is a condition people with diabetes develop when blood vessels in the retina are damaged.(6) Diabetes retinopathy can manifest in different ways. According to the National eye institute, the blood vessels in the eye may become swollen and leak fluid. Other people may have an abnormal growth of new blood vessels on the retina. Diabetic retinopathy is characterized in four stages. Three of the stages are called nonproliferative and one is called proliferative.(7) There is also a condition called macular edema which takes place in the macula and includes diffuse or focal vascular leakage.(8) 

The stages of diabetic retinopathy are:

•    Mild Nonproliferative Retinopathy- This is when there are areas of swelling in the retina’s blood vessels that resemble balloons.(7) In mild nonproliferative retinopathy, microaneurysms develop which are sack-like pouches in the vessels and are the “hallmark” sign of this condition.(9) With screening and detection at this level, it can be the first step to prevention of the progression to the next stage of diabetic retinopathy. Read more information about the formation of microaneurysms.

•    Moderate Nonproliferative Retinopathy At this stage of nonproliferative retinopathy, some blood vessels that nourish the retina are blocked.(7)

•    Severe Nonproliferative Retinopathy The number of blood vessels that are blocked increase. Areas of the retina are deprived of a blood supply. This is the stage right before new blood vessels form to nourish the retina.(7)

•    Proliferative Retinopathy New blood vessels are formed and “proliferate” to nourish the retina. These new blood vessels are very fragile. They can rupture causing blood to leak which can cause vision loss and blindness.(7)

At any stage of non-proliferative diabetic retinopathy, macular edema can take place which can cause rapid vision loss. Macular edema can lead to changes in blood vessels in the macula. These blood vessels can break and bleed into the macula.(10) 

Question 3: Is there a way that I can see what vision changes may look like for a person with non-proliferative diabetic retinopathy over time?
The American Academy of Ophthalmology has a non-proliferative diabetic retinopathy vision simulator that may be helpful in answering this question. 

Question 4: What exactly happens to the eye in a person who has diabetic retinopathy? 
An animation of diabetes retinopathy, presented by the National Eye Institute (NEI), may be helpful in understanding what happens to the eye. 

Question 5: What are the symptoms of diabetic retinopathy?
According to Medline Plus, many people in the first stages of diabetic retinopathy have no symptoms until bleeding occurs in the eye. When people have symptoms, they may include;
•    Blurry vision or slow vision loss
•    Floaters in the eye
•    Areas where vision is lost or in shadows
•    Difficulty with night vision (11) 

Question 6: What are the risk factors for diabetic retinopathy?  
In 2012 a study called the Global Prevalence and Major Risk Factors of Diabetic Retinopathy was published. Thirty-five studies were reviewed which took place throughout the world between the years 1980-2008. A total of 22,896 individuals with diabetes were represented in this research. Risk factors for diabetic retinopathy identified by the authors include the following:
•    Longer duration of diabetes
•    Poor blood glucose control
•    Poor blood pressure control
•    Increased total serum cholesterol (12)

A separate study was conducted that reviewed data from the National Health and Nutrition Survey (NHANES) conducted between the years 2005-2008. Subjects included 1,200 people with diabetes. They filled out a survey and had a retinal examination. This study concluded that high hemoglobin A1c values are correlated with severe diabetic retinopathy. For each increased percentage value of A1c the research found that there is a 25 percent greater risk of having severe diabetic retinopathy compared to those with lower hemoglobin A1c values.(13)

Researchers also noted that 70 percent of people with diabetes retinopathy were not aware that diabetes affected their eyes. They also concluded that the amount of time a person has had diabetes is strongly correlated with diabetes retinopathy.(13)
Pregnancy also increases the risk for diabetic retinopathy and can cause progression if the woman already has it. With treatment the changes may be reversed after giving birth.(14) 

Question 7:  When and how often should a person with diabetes get screened for diabetes retinopathy?
According to the standards of care for diabetes (2013), it is recommended for people with type 1 diabetes older than 10 years of age have an initial dilated and comprehensive eye examination within the first 5 years of diagnosis by an ophthalmologist or optometrist who is experienced in diagnosing the presence of diabetic retinopathy and knows how to manage the condition. People with type 2 diabetes should have the same type of examination within a short period of time after diagnosis. These exams are usually repeated at least every year. Women with diabetes planning a pregnancy should have a comprehensive eye examination and have counseling about the risks associated with progression or development of this condition. In the first trimester of pregnancy an eye examination should take place with close follow up during pregnancy and one year after.(15) View the American Diabetes Association presentation for more information on screening.

Question 8: To help prevent diabetes retinopathy, what should I discuss with my physician? 
•    Ask your physician if it is appropriate for you to keep your hemoglobin A1c levels between 6-7 percent.(16) 
•    Discuss what your blood pressure and blood lipid level goals are healthy for you to help prevent retinopathy.(17)
•    Make sure you discuss the optimal eye exam schedule for you with a retinal specialist. Make your appointments and keep them.(17)  

Question 9: What is the treatment for diabetic retinopathy and macular edema?
According to the American Society of Retina Specialists, there are many treatments available for diabetic retinopathy. These include laser treatments and injections of medications into the eye. Procedures are available to help prevent, treat and possibly reverse damage from diabetic retinopathy.(18) For more information on possible treatments visit the American Society of Retina Specialists
Laser surgery may also benefit people diagnosed with macular edema. One significant study found that this surgery reduces the incidence of moderate vision loss over a 3 year period from 30 percent to 15 percent.(19)  

This completes our three part series on vision and diabetes. As you can see, people with diabetes are at a great risk for vision loss and potential blindness.  Make sure you discuss potential problems with your health care team. Your healthy vision depends on it!