Patients with diabetes mellitus (DM) can have abnormal blood sugar levels and this can affect the eye in many ways. In diabetic retinopathy (DR), the retinal blood vessels are damaged. Diabetic retinopathy can affect type I (insulin dependent) and type II (non-insulin dependent) diabetics.
There are three main ways that diabetic retinopathy causes vision loss: diabetic macular edema, proliferative diabetic retinopathy, and poor perfusion of the retina due to lack of normal blood fl¬ow (ischemia).
Non-proliferative diabetic retinopathy (NPDR) and background diabetic retinopathy (BDR) describe early stages of diabetic retinopathy. Blood vessel damage in diabetic retinopathy can lead to abnormal leakage of fluid and blood into the retina. This leakage can cause the retina to swell. If this swelling occurs in the macula it is called DME and vision can be affected. This is the most common cause of visual loss in patients with diabetes and ranges from mild to severe.
PDR occurs when abnormal blood vessels grow into and on top of the retina. These abnormal blood vessels are fragile and can bleed into the eye causing vitreous hemorrhage. This can cause dark floaters and may cause immediate and severe loss of vision. Pulling and contraction of these abnormal vessels and their associated scar tissue on the retina can lead to a tractional retinal detachment, a condition where the retina is pulled away from the back of the eye leading to loss of vision.
Diabetic retinopathy is diagnosed by your ophthalmologist during a dilated eye exam. Your doctor may obtain photographs of the retina and diagnostic tests, including ocular coherence tomography and fluorescein angiography to help guide treatment.
Prevention is the best treatment. Optimal blood sugar, blood pressure, cholesterol and weight control can reduce the long-term risk of vision loss from diabetic retinopathy. Cooperation with your primary care physician is very important to help keep your diabetes and other cardiovascular risk factors under control. Because of the effects diabetes can have on the eye, patients with diabetes should be seen by an eye doctor and obtain a dilated fundus exam at least once a year. Early detection of diabetic retinopathy allows the best chance for maintaining good vision. Once the diagnosis of diabetic retinopathy has been made, more frequent eye exams may be necessary. Checking your blood sugar at home, recording your blood sugars in a notebook, and showing these numbers to your primary care physician is critical to success in controlling your disease.
Medical treatment may involve the use of injections of medicine into your eye (intravitreal injections) to treat macular edema. Recent science has shown that DME and PDR are controlled by a signal sent from damaged retina called vascular endothelial growth factor (VEGF). Several VEGF blocking drugs (including Lucentis, Avastin and Eylea) and other medications (steroids and steroid implants) when injected into the eye can cause DME and PDR to regress. Most of these agents provide only temporary relief and need to be given repeatedly over a prolonged period of time.
Laser treatment may be recommended for people with DME. The goal of this treatment is to prevent further loss of vision. The laser seals and prevents them from growing. For macular edema the laser is focused on parts of the retina outside of the macula. Multiple laser treatments may be necessary. This is not a curative procedure and does not always prevent further loss of vision.
If you have any questions or concerns, it is important that you discuss them with your retina specialist.
Vitrectomy surgery in the operating room may be recommended if bleeding from diabetic retinopathy causes a vitreous hemorrhage and associated vision loss. Additionally, surgery may be needed to treat tractional retinal detachment in the setting of extensive blood vessel and scar tissue growth.