Diabetic Retinopathy

Overview

Diabetic retinopathy (DR) is the most common form of vison loss associated with diabetes, affecting approximately 500,000 Canadians, and is the leading cause of blindness among working-age adults. When left untreated the condition may advance into diabetic macular edema (DME), where damaged blood vessels leak into the macula, the central area of the retina, resulting in blurred vision and dark or distorted images. If you have diabetes it is important to have regular appointments with your eye specialist to undergo specialized screenings, which will test to see if your eyes are showing signs of retinopathy. Since the early stages of the disease do not always carry symptoms, these screenings are essential; there is no reliable cure for vision loss resulting from diabetic retinopathy, but the disease can be managed—and vision loss prevented—if it is diagnosed early enough, before damage to the retina occurs.

In the “non-proliferative” form of diabetic retinopathy, blood sugar levels from diabetes damage the blood vessels that nourish the retina, the light-sensitive tissue at the back of the eye. This damage will often lead to dot-like hemorrhages throughout the retina. These often don’t carry any symptoms, however, and with adequate control of diabetes the damage in the eye can be reversed.

Comparison highlighting differences between an undamaged eye and one suffering from diabetic retinopathy, including hemorrhages and swelling in the macula. Image is from the Manhattan Eye Specialists.

Advancement of the disease can lead to fluid leaking into the retina, resulting in swelling. At this stage, which is typically diabetic macular edema, symptoms such as blurring may begin to manifest; alternatively, the patient’s vision may be normal, which is why regular eye tests are so important.

When the disease advances, new blood vessels grow to compensate for the damaged old ones, but they are weaker and more susceptible to breaking and rupturing—this is the “proliferative” stage of the disease. This can lead to bleeding into the vitreous cavity, which may present as floaters or spots in one’s vision.

The chances of developing diabetic retinopathy increase the longer you have diabetes. The disease can also increase your chances of developing neovascular glaucoma and cataracts.


Content on this page was written by Dr. Chad Andrews and Dr. Mary Sunderland, and was edited and approved by Dr. Deepa Yoganathan. The information was most recently updated on August 23, 2018.

Symptoms and Diagnosis

Most often, there are no symptoms in diabetic retinopathy. If you do have symptoms, they may include distorted images, flashes of light, blurring, sudden loss of sight, and floaters. Since damage to the eyes can happen before the appearance of these symptoms—even before diabetes is diagnosed, in some cases—regular exams by an ophthalmologist or optometrist are crucial. To set-up regular eye exams, you can speak with your eye care professional directly or have your health care provider refer you to a specialist.

The most common diabetes eye exam, the safe and effective “dilated eye exam,” entails the following:

  • Drops are put into your eyes to dilate your pupils.
  • Once the pupil is enlarged, the eye care provider can examine your eye using a magnifying lens that provides a clear view of the back of the eye.
  • Examining the retina and the blood vessels at the back of the eye, your eye care provider is able to develop a diagnosis and determine if you have eye damage as a result of diabetes.
  • If performed by an optometrist, the exam may be covered by your provincial or territorial health insurance, so it is important to consult your plan.
  • If performed by an ophthalmologist, the exam is always covered by provincial health insurance.

Existing Treatments

It is important to note that monitoring and controlling blood sugar levels is important, as well as taking any diabetes medicine prescribed by your doctor—if diabetes is not managed well, the chances of diabetic retinopathy increase. While there is no guaranteed approach to restoring vision once it has degraded, there are several techniques for slowing or halting vision loss once the disease has been diagnosed.

  • Anti-VEGF injections: “VEGF” stands for “anti vascular endothelial growth factor,” which is a protein that facilitates the development of new blood vessel growth in the eye. The injections are designed to stop the creation of new, abnormal blood vessels that leak into the retina (hence “anti,” or “against” VEGF). Delivered directly into the eye, the injections have emerged as the medical “standard of care” in the field, and when delivered regularly—often monthly—they can be very successful in managing the disease and minimizing further vision loss.
  • Laser surgery: as with injections, laser surgery is used in some cases to prevent further vision loss. This is done by targeting tissue in the eye that has been damaged by diabetic retinopathy, typically the problematic blood vessels themselves or in some cases portions of the retina that are considered nonessential.
  • Vitrectomy surgery: an eye care specialist may recommend a form of surgery called “vitrectomy”. This involves removing the vitreous gel in the back of the eye if there is too much non-clearing blood or if there is a retinal detachment from the diabetes. The vitreous is replaced with saline solution.

Clinical Trials

Clinical trials are essential to the scientific process of developing new treatments: they test the viability and safety of experimental drugs and techniques, called “interventions,” on human beings. While there is no guarantee that enrolling in a clinical trial will provide any medical benefit, some patients do experience positive results after receiving an experimental therapy.

Read Our Clinical Trials Guide

The website clinicaltrials.gov is a centralized database of clinical trials that are offered globally. But as the disclaimer on the site’s home page states, there is no guarantee that a listed trial has been evaluated or approved—the National Institutes of Health runs the site but does not vet its content. This means that there could be bogus or dangerous trials listed that are preying on patients. It is essential that you discuss a clinical trial with your ophthalmologist before enrolling, and that you pay close attention to enrollment criteria.

If you are interested in exploring what is available on the site you can click on the button below, which will take you to clinicaltrials.gov and initiate a search for trials relevant for patients living with diabetic retinopathy.

CLINICAL TRIALS FOR DIABETIC RETINOPATHY

Research Developments and Health Policy

The Foundation Fighting Blindness is committed to advancing the most promising sight-saving research, and has invested over $33 million into cutting-edge science since the organization was founded. Recognizing that science is tied to policy frameworks, the Foundation is also actively involved in health policy activities across Canada. Below is a list of some recent developments in research and policy related to diabetic retinopathy:

    • Anti-VEGF drugs: there are several anti-VEGF drugs on the market in Canada, including Eylea and Lucentis. And there are newer treatments used in some cases that are implant-based, such as Ozurdex. These involve an injection that places an implant into the eye’s vitreous, the jelly-like fluid that gives the eyes its shape; the implant then releases anti-VEGF medicine over a period of time, resulting in fewer injections being required. A cancer drug called Avastin is also being used in some cases as a traditional anti-VEGF drug. There is a debate in Canada regarding the efficacy and safety of using Avastin in this way, and the Foundation Fighting Blindness has been involved at several stages and in different contexts, including a consultation process with the Canadian Association for Drugs and Technologies in Health (CADTH). You can read more about the Foundation’s involvement by clicking the button below.

Read More About the Foundation’s Involvement

    • Retinal imaging and detection: detecting and diagnosing diabetic retinopathy is incredibly important—the earlier the disease is found, the better the chance to prevent any loss of vision. There are several forms of imaging being used today, including OCT, OCT angiography, widefield imaging, and fluorescein angiography. Exciting developments are taking place in the field of diagnostic imaging that could facilitate rapid and early detection, including the deployment of complex algorithms capable of screening images of eyes (called “fundus photographs”). Already this software is showing an ability to distinguish images of healthy eyes from ones showing early signs of diabetic retinopathy—you can read more about some of these development by clicking the button below.

Read More About These Developments

Educational Resources

The page you are now on provides information on achromatopsia, but the Foundation Fighting Blindness has developed additional resources that can be helpful in plotting an optimal path through vision care. Below is a link to our must-read resources, where you will find information on genetic testing, clinical trials, stem cell research, and more as well as a link to Vision Quest (the FFB’s in-person educational events). The list will update as new resources are added.

Must-Read Resources

Vision Quest Educational Series