This month we will continue our discussion about diabetes and diabetic eye disease.
Last month, we began reviewing diabetes and non-proliferative diabetic retinopathy. Now, we will focus on proliferative diabetic retinopathy (PDR).
How is diabetic eye disease in the retina defined?
As we discussed, diabetic retinopathy (DR) and diabetic macular edema (DME) are the retina-related changes in diabetic eye disease. In diabetic retinopathy, the blood vessels of the retina are affected. This is further separated into non-proliferative and proliferative disease. PDR is more severe than NPDR. Diabetic macular edema is a consequence of diabetic retinopathy. It is swelling or a collection of fluid in the center of the retina called the macula.
When someone has high blood sugar, the environment of the eye changes. If the sugar stays very high for a long time, new blood vessels can grow in the eyes that are not normal. These new blood vessels are the hallmark of proliferative diabetic retinopathy.
What puts people at higher risk of developing proliferative diabetic retinopathy (PDR)?
Chronically elevated sugar in the body damages the blood vessels in the retina leading to diabetic retinopathy. This damage to the blood vessels can cause them to leak fluid or blood. The risk also increases with a longer duration of diabetes.
What are the symptoms of PDR?
All forms of diabetic eye disease can cause vision loss and blindness. There are usually symptoms of blurry vision, distortions, or cloudy vision. There can also be floaters, spots in the vision, or loss of peripheral vision.
How is it detected?
A comprehensive exam including checking the vision and dilating the eyes to view the retina are necessary to detect PDR. Proliferative disease is when new, abnormal blood vessels grow in the iris, optic nerve, and/or the retina. Photos are taken to diagnose and monitor the disease.
The circle highlights new blood vessels forming on the iris.
This shows new blood vessels forming on the optic nerve.
This image shows a vitreous hemorrhage. This is bleeding in the back of the eye from an abnormal blood vessel. The blood collects in the posterior chamber, the space in front of the retina.
This photo is also of a vitreous hemorrhage. It has spread throughout the back of the eye making the retina look blurry.
If the disease advances, the retina may separate. This is called a retinal detachment. The detachment in the photo is around the optic nerve.
Other photos taken during an exam are to determine the severity of disease. Optical coherence tomography, OCT, looks for macular edema and fluorescein angiography, FA, looks for damaged and leaking blood vessels. FA involves injecting a dye into the arm and taking photos as the dye goes through the blood vessels in the eyes. This is particularly useful in finding leaking blood vessels in PDR. We look for these blood vessels in the retina as well as the optic nerve.
This photo is of a normal fluorescein angiogram. The dye lights up as it goes through the blood vessels.
This photo is of a patient with proliferative diabetic retinopathy. The red arrow points to abnormal blood vessels that are leaking the dye. The yellow arrow shows an area of the retina that is not getting proper nutrition from the blood.
What are the treatments for proliferative diabetic retinopathy?
Prevention: Non-proliferative diabetic retinopathy can evolve into the proliferative form. Early changes can occur in the eyes without the person knowing. It is very important to get a dilated comprehensive exam once a year to look for changes. If retinopathy is detected, the exams are more frequent.
Controlling sugar, BP, and cholesterol: Studies have shown that maintaining normal sugar levels, blood pressure, and cholesterol reduce the risk of developing eye disease and vision loss. The hemoglobin A1c is used to determine sugar levels over a three-month period. A lower A1c reduces the risk of developing retinopathy.
Lifestyle modifications: Smoking and obesity are risk factors for diabetes and therefore play a role in diabetic eye disease as well.
Laser: There are several types of laser treatments. The one used for PDR is called panretinal photocoagulation (PRP). It involves making small burns in the retina to treat the abnormal blood vessels and prevent them from bleeding.
This is the retina after laser treatment.
Injections: Injections are given in the eye when there is bleeding from blood vessels. The medications used are in the class called anti-VEGF medications. VEGF, vascular endothelial growth factor, is a normal compound in the body that regulates the growth of blood vessels. In PDR, there is too much of this compound. The drugs block the effects of VEGF to shrink the abnormal blood vessels and clear the blood.
Surgery: Occasionally, surgery is a required treatment for PDR. If bleeding cannot be cleared with injections, surgery is done to remove the blood. The surgery is called a vitrectomy. This removes the vitreous so there is no blood in the eye. Surgery is also used if PDR causes a retinal detachment. The vitrectomy removes the vitreous so it is not pulling on the retina. Then, laser is performed to help the retina reattach. Usually, the surgeon places a gas or oil in the back of the eye. This also helps the retina stick back together.
Low vision tools: There are many aids to help patients with poor vision from diabetic retinopathy including magnifiers, high-powered lenses, large print materials, talking clocks and calculators, closed-circuit televisions, and computer-based aids.
Return next month to continue our discussion on diabetic eye disease!