Diabetic retinopathy (die-uh-BET-ik ret-ih-NOP-uh-thee) is a diabetes complication that affects eyes. It’s caused by damage to the blood vessels of the light-sensitive tissue at the back of the eye (retina). These blood vessels can swell and leak. Or they can close, stopping blood from passing through. Sometimes abnormal new blood vessels grow on the retina. All of these changes can steal your vision.
Diabetic retinopathy is broadly classified as non-proliferative, which is subclassified as mild, moderate, or severe, or proliferative, which is less common but causes more severe visual loss. Diabetic retinopathy is present in about one-third of patients in whom diabetes has been diagnosed, and about one-third of those have sight-threatening disease.
Retinopathy increases in prevalence and severity with increasing duration and poorer control of diabetes. In type 1 diabetes, retinopathy is not detectable for at least 3 years after diagnosis. In type 2 diabetes, retinopathy is present in about 20% of patients at diagnosis and may be the presenting feature.
Diabetic retinopathy does not usually produce symptoms during the early stages. Symptoms typically become noticeable when the condition is more advanced.
Diabetic retinopathy tends to affect both eyes. The signs and symptoms of this condition may include:
- blurred vision
- impaired color vision
- eye floaters, or transparent spots and dark strings that float in the person’s field of vision and move in the direction that the person looks
- patches or streaks that block the person’s vision
- poor night vision
- a dark or empty spot in the center of the vision
- a sudden and total loss of vision
Treatment includes optimizing blood glucose, blood pressure, kidney function, and serum lipids, although such measures are probably more important in preventing the development of retinopathy than in influencing its subsequent course. Fenofibrate and renin-angiotensin system inhibitors are beneficial even in established retinopathy.
Macular edema and exudates, but not ischemia, may respond to laser photocoagulation; to intravitreal administration of a VEGF inhibitor (ranibizumab [Lucentis], pegaptanib [Macugen], bevacizumab [Avastin], or aflibercept [VEGF Trap-Eye, Eylea]) or corticosteroid (triamcinolone, dexamethasone implant [Ozurdex], or fluocinolone implant [Retisert, Iluvien]); to vitrectomy; or to intravitreal injection of a serine protease (ocriplasmin [Jetrea]) to release vitreo-retinal traction.
Proliferative retinopathy is usually treated by panretinal laser photocoagulation, preferably before vitreous hemorrhage or tractional detachment has occurred. Regression of neovascularization can also be achieved by intravitreal injection of a VEGF inhibitor.
In patients with severe nonproliferative retinopathy, fluorescein angiography can help determine whether panretinal laser photocoagulation should be undertaken prophylactically by determining the extent of retinal ischemia. Vitrectomy is necessary for removal of persistent vitreous hemorrhage, to improve vision and allow panretinal laser photocoagulation for the underlying retinal neovascularization, for treatment of tractional retinal detachment involving the macula, and for management of rapidly progressive proliferative disease.
Proliferative diabetic retinopathy, especially after successful laser treatment, is not a contraindication to treatment with thrombolytic agents, aspirin, or warfarin unless there has been recent intraocular hemorrhage.
Without treatment, diabetic retinopathy can lead to various complications.
When blood vessels bleed into the main jelly that fills the eye, known as the vitreous, this is called vitreous hemorrhage. In mild cases, the symptoms include floaters, but more severe cases can involve vision loss, as the blood in the vitreous blocks light from entering the eye.
If the retina remains undamaged, bleeding in the vitreous can resolve itself.
In some cases, diabetic retinopathy can lead to a detached retina. This complication can happen if scar tissue pulls the retina away from the back of the eye.
It usually causes the appearance of floating spots in the individual’s field of vision, flashes of light, and severe vision loss. A detached retina presents a significant risk of total vision loss if a person does not get treatment.
The normal flow of fluid in the eye may become blocked as new blood vessels form, leading to glaucoma. The blockage causes a buildup of pressure in the eye, increasing the risk of optic nerve damage and vision loss.