In the earlier stages, damaged blood vessels within the retina leak blood and fluid causing areas of swelling and deposition of exudates. When the central retina is affected it is called macular edema and can cause visual symptoms. As the disease progresses, instead of leaking, the blood vessels close which deprive the eye of oxygen and nutrients. This condition is called ischemia. In response to the ischemia, abnormal blood vessels grow on the surface of the retina and cause scarring and bleeding into the cavity of the eye. The growth of the abnormal vessels is called neovascularization and the bleeding is known as a vitreous hemorrhage. The scarring can lead to shrinking and subsequent pulling of the retina causing it to detach itself from the back of the eye. This is called a traction retinal detachment. If the abnormal blood vessels grow on the front of the eye, drainage channels may be blocked causing increased pressure within the eye. This is a painful condition known as neovascular glaucoma.
In its early stages, diabetic retinopathy has no visual symptoms. Vision is compromised when edema and/or ischemia occurs in the macula. With the development of scarring and neovascularization, more severe vision loss can occur due to a vitreous hemorrhage or a traction retinal detachment.
Diabetes mellitus is the underlying cause of this condition. Blood sugar and blood pressure control are essential in reducing the risk of developing diabetic retinopathy and subsequent loss of vision.
The best treatment for diabetic retinopathy is strict control of blood sugar levels. Diagnosis is based on findings of a dilated eye exam and retinal imaging studies using fluorescein angiography and optical coherence tomography. Once the disease is present and symptoms appear, multiple treatment modalities may be used depending on clinical findings and the severity of the condition. Therapies include laser surgery, intravitreal injections and vitrectomy surgery.