What is diabetic retinopathy?
Diabetic retinopathy is a result of diabetes and it effects the retinal blood vessels. The lining of the retinal blood vessels is slowly damaged, and this starts a cascade of events. The vessels become leaky, the retina can become starved of oxygen and nutrients, and bleeding can occur in the eye. Diabetic retinopathy is more common in people who have had diabetes for an extended period of time. However, the early stages of the disease do not cause any visual changes; so screening by a retina specialist is very important and can prevent vision loss.
What are the stages of diabetic retinopathy?
When you are assessed by your retina specialist, you will undergo a dilated retinal examination. Photographs of your retina will help detect diabetic retinopathy and can be useful to show progression or change. After examining your retinas, your specialist will be able to stage the retinopathy.
Mild Non-Proliferative Diabetic Retinopathy
Only mild blood vessel changes are seen at this stage. The earliest visible change is a microaneurysm, which is a tiny outpouching in the wall of the small retinal blood vessels. These early changes are not vision threatening and do not require any treatment.
Moderate Non-Proliferative Diabetic Retinopathy
In this stage, more advanced blood vessel changes are noted. For example, hemorrhages can be seen within the retina.
Severe Non-Proliferative Diabetic Retinopathy
In this stage, the retinal blood flow becomes more impaired. Changes are seen throughout the retina because of reduced oxygen and nutrient delivery. Microaneurysms, hemorrhages and hard exudates may be seen.
Proliferative Diabetic Retinopathy
As the retinal blood flow becomes more abnormal, the retina becomes starved of oxygen. The way the body tries to fix this, is by sending a message to the eye to grow more blood vessels. Unfortunately, these new blood vessels cause more harm than good. They are very fragile and can cause bleeding within the eye. Eventually, they can lead to scar tissue formation and to retinal detachment. At this stage, urgent treatment is required to halt the growth of these new vessels.
What causes vision loss? - Cataract
Cataract is a common problem encountered by patients with diabetes. Sometimes cataract is present at the same time as the diabetic retinopathy. Cataracts may occur at a younger age for those with diabetes. Thankfully, this problem can be cured with cataract surgery.
When retinal blood vessels become damaged by diabetes, they can get "leaky". Fluid can pass through the vessel into the surrounding retina. The retina is like a sponge, if there is extra fluid around, it will soak up the fluid and become "thick" or "swollen". When this swelling occurs in the central area of the retina, we refer to it as macular edema. This problem can cause blurriness, abnormal color vision and reduced clarity of vision. Treatment options include anti-VEGF injections and laser surgery. Your specialist will determine which treatment is best for your eye. We can document the extent of the swelling with an in-office scan called optical coherence tomography (OCT).
Like macular edema, this condition also affects the central area of the retina. The blood supply to this critical portion of the eye is choked by the effects of the diabetes. The diagnosis of this problem is often aided by a special test done at the hospital called fluorescein angiography (DR04). Unfortunately, there is no treatment available for this. Macular ischemia can result in long term reduction of the central vision.
In patients with proliferative retinopathy, abnormal blood vessels (neovascularization) start to grow. These new vessels can cause bleeding in the vitreous cavity which is called vitreous hemorrhage. When this occurs, the symptoms are new floaters and poor vision. For those who do not undergo regular screening, this is the first visual change noticed from diabetes. Sometimes the blood will clear with laser treatment or anti-VEGF injections. However, retinal surgery is sometimes required to clear the blood from inside the eye.
In proliferative retinopathy, the new blood vessels may start to contract and form scar tissue in the eye. This scar tissue can pull on the retina and create a detachment. These retinal detachments are a serious problem, and can be challenging to cure. Our goal is to prevent this problem by regular screening for our patients. However, both of our surgeons are highly trained in the surgical treatment of this problem.
Who is at risk of diabetic retinopathy?
Patients with Type I or Type II diabetes may develop retinopathy. Regular screening is crucial because the early stages of the disease do not cause any visual changes. Everyone who has been diagnosed with diabetes, should have an annual eye exam. This should include dilation of the pupils and retinal evaluation. If diabetic retinopathy is present, more frequent follow-up visits may be required.
What is the treatment?
Depending on the cause of vision loss, your treatment will be specifically tailored to your eyes. The following is a list of treatments currently available to our patients with diabetes.
Modify your risk
You can reduce your risk of retinal problems by ensuring that your general health is excellent. Good sugar control and blood pressure control have been shown to reduce the progression of this eye problem. Also, smoking cessation can benefit the health of the retinal blood vessels.
Focal macular laser
This is a common treatment option for macular edema. Your retinal specialist will identify the "weak areas" in the blood vessels which are leaking fluid into the retina. These "weak areas" are then cauterized with the energy from the laser beam. This treatment is not painful, and can be done at the office. Sometimes this treatment may be needed multiple times. This type of laser has been shown to reduce vision loss by 50%.
Pan Retinal Photocoagulation
This type of laser is commonly employed for patients with proliferative retinopathy. With this laser, the peripheral retina is ablated. The goal of the treatment is to conserve the blood flow in the retina for the important, central retina. Side effects of this treatment include a reduction in side vision, change in night vision and temporary blurriness. This laser can take 5-10 minutes per session. It can be uncomfortable, so an eye is usually treated over 2-3 sessions.
Please see the section on anti-VEGF treatment for more information. Our retina specialists have access to both of the anti-VEGF medications (Avastin and Lucentis). In Saskatchewan, patients with diabetic macular edema qualify for Lucentis coverage. These injections are useful for both macular edema and neovascularization.
Usually, retinal surgery is the last option but it can be very effective and helpful. For patients with vitreous hemorrhage or retinal detachment, surgery is often required. In this surgery, the vitreous gel is removed from the eye with specialized instrumentation. Laser is often applied to the retina at the time of surgery. Both of our surgeons are trained in the most advanced vitrectomy techniques. Retina surgery is done as a day surgery at Saskatoon City Hospital.