Diabetic Retinopathy: Causes, Symptoms & Treatment

Diabetic retinopathy is damage to the retina of the eye caused by the metabolic disease diabetes mellitus.

What is diabetic retinopathy?

Diabetic retinopathy represents a secondary disease of diabetes mellitus. Diabetes mellitus damages the smallest arterial blood vessels through deposits and scarring, resulting in circulatory disturbances in the affected organs (e.g., the eye) (microangiopathy). Damage to the retina due to scarring results in impaired vision, which can lead to blindness. Diabetic retionopathy, which causes 30% of all cases of blindness in Europe, is the most common cause of blindness in people between 20 and 65 years of age. About 90% of all people with type 1 diabetes and about 25% of all people with type 2 diabetes also develop diabetic retinopathy after 15 to 20 years of diabetes mellitus. The first eye changes occur on average after 10 to 13 years. In one in fifty diabetics, diabetic retinopathy leads to blindness.

Causes

The main trigger of diabetic retinopathy is long-standing diabetes mellitus. The risk of diabetic retinopathy increases with inadequately controlled blood glucose levels. The occurrence of diabetic retinopathy or its progression can be avoided or at least delayed if blood glucose is strictly controlled. The risk of developing diabetic retinopathy is also increased during phases of life characterized by hormonal changes (e.g., during puberty or pregnancy). There is an additional risk of disease during pregnancy if blood glucose is poorly controlled, if blood glucose is controlled too quickly in the early stages of pregnancy, and if preeclampsia is associated with high blood pressure (hypertension). In general, hypertension, hyperlipidemia (elevated blood lipids), and renal damage due to diabetes favor diabetic retinopathy.

Symptoms, complaints, and signs

In this disease, there are various symptoms of the eyes. Since the disease usually always occurs due to diabetes, those affected also suffer from diabetes in the process. First and foremost, this results in various visual disturbances and generally weak vision. Patients are therefore dependent on wearing visual aids in their daily lives and thus also suffer from restrictions in everyday life. During vision, black spots may also appear in the visual field, which cannot be removed without further treatment. Likewise, hemorrhages occur in the vitreous body itself, which can also interfere with vision. If the disease is not treated, it will eventually lead to complete blindness. This can no longer be reversed. Children in particular can suffer severely from sudden and irreversible visual impairment, and depression or other psychological limitations may result. The infection can also spread to the rest of the body if the disease is not treated. The kidneys and heart are also attacked, so that these organs can also be permanently damaged. Without treatment, the patient’s life expectancy is significantly reduced. In some cases, patients additionally suffer from delayed wound healing.

Diagnosis

If diabetic retinopathy is suspected, the first step is to perform an opthalmoscopy (funduscopy, mirroring of the back of the eye), which examines the blood vessels of the retina. With direct funduscopy, the vascular exit points located in the center and the “yellow dot” (macula), which has the greatest density of visual cells, are checked using a concave mirror or a converging lens. Indirect funduscopy has slightly lower magnification, but provides the examining physician with a better overall view that includes the periphery of the retina and allows for a three-dimensional assessment. The imaging technique of fluorescein angiography is also used to examine the fundus of the eye. In this procedure, dyes such as indocyanine green or fluorescein are injected intravenously in parallel with medication to dilate the pupil. Of interest for the examination is how quickly the dyes serving as contrast agents reach the retina and how they are distributed there in order to be able to diagnose diabetic retinopathy if necessary.

Complications

Diabetic retinopathy is associated with diabetes mellitus that is long-standing and associated with a wide variety of complications. The long-standing elevation of sugar causes it to chemically combine with proteins to form larger molecules that clog the smallest vessels, causing blood flow to dry up. This leads to a reduced supply of blood to the eye, for example (diabetic retinopathy). The affected person notices that his or her vision is deteriorating, visual field losses are conceivable. The retinopathy can even lead to blindness. This can mean impairments in everyday life, among others in road traffic. Furthermore, diabetes can also affect the kidneys (diabetic nephropathy), in the worst case it can lead to kidney failure. Initially, there is an increased excretion of urine, which in the course of time becomes less and less. In addition, the blood becomes overly acidic, resulting in an increased concentration of potassium in the blood (hyperkalemia). This can lead to cardiac arrhythmias, which can even end in cardiac arrest. Impairment of nerve function (diabetic neuropathy) can also be explained due to diabetes. This leads to disturbances in sensitivity and paralysis. As a result, wounds on the foot can be recognized more poorly, since pain stimuli are no longer perceived correctly. The wounds can increase in size as they progress and cause irreversible tissue damage (diabetic foot).

When should you see a doctor?

Diabetic retinopathy is initially asymptomatic and usually goes unnoticed for a long time. To detect early signs of disease, type 2 diabetics should have an ophthalmologic examination immediately after diagnosis. Annual check-ups are then recommended. Type 1 diabetics are advised to make their first visit to the ophthalmologist no later than the fifth year after the diagnosis of diabetes or at the age of eleven; in the case of poorly controlled blood glucose levels, a much earlier examination is necessary. Pregnant diabetic women are recommended to have ophthalmological check-ups every three months. In principle, any deterioration in vision in known diabetes mellitus should prompt an examination by an ophthalmologist: Signs may include difficulty reading, rapid eye fatigue, or headaches triggered by overexertion. A visit to the ophthalmologist should be made immediately if visual disturbances such as blurred vision or dancing black dots occur. If this “sooty rain” occurs suddenly and is accompanied by a visual field loss, an acute hemorrhage or complete retinal detachment must be assumed. Immediate ophthalmologic treatment is absolutely necessary in this case to preserve unrestricted vision. In addition to ophthalmologic checkups, patients with known diabetic retinopathy should also have regular checkups with their primary care physician to ensure that their blood glucose, blood lipid levels, and blood pressure are optimally adjusted.

Treatment and therapy

Diabetic retinopathy can only be successfully treated if the underlying diabetes mellitus is consistently managed. Although both diabetic retinopathy and diabetes mellitus currently have no definitive cure, the vascular damage that has occurred in the retina can be improved or progression of the disease prevented. In order to avoid severe retinal damage, it is important to recognize and treat diabetic retinopathy as early as possible. The patient must consistently implement diabetes treatment measures such as adequate nutrition and abstaining from cigarette and excessive alcohol consumption. Hypertension, if present, also requires treatment. If new vessels have formed in the retina or if there is bleeding in the vitreous in front of the retina, various laser therapies can be performed. In the case of fluid retention at the yellow spot (macular edema), an injection procedure is used in which drugs containing cortisone or drugs that inhibit vessel growth and cause the center of the retina to swell are injected directly into the vitreous. However, the injection of cortisone preparations must be repeated.If retinal detachment has occurred or if there is continued bleeding into the vitreous, surgery is performed to remove the bleeding caused by diabetic retinopathy and reattach the retina.

Outlook and prognosis

Diabetic retinopathy is not a curable disease. It has an unfavorable prognosis. It is also complicated by the fact that it is often diagnosed at a very advanced stage. It remains asymptomatic for a long time and is therefore usually diagnosed late. Treatment with medication is unsuccessful with the current medical options. The decisive factor for a better course of the disease is the behavior of the patient as well as good medical treatment. With an optimal adjustment of the blood glucose level, the progress of the disease can be influenced. In some cases it is possible to stop the deterioration of diabetic retinopathy. The visual ability remains at a continuous strength in these patients. To achieve this, the patient must become accustomed to a diet adapted to his or her physical needs. This often requires a complete change in food intake. This must be adhered to for the rest of his life. Deviations lead to a deterioration of health and an increase in complaints within a short period of time. In addition to a special diet, the organism needs sufficient exercise. Excess weight must be avoided and the blood sugar level must be checked regularly. If the patient manages to adhere to the guidelines, there is a possibility that there will be no further decrease in vision. Laser therapy can also improve the visual system in some cases.

Prevention

The best possible prophylaxis against diabetic retinopathy is to detect diabetes mellitus and the diabetic retinopathy based on it as early as possible and to provide targeted treatment. The imminent loss of vision can be avoided with early therapy. Since diabetic retinopathy often does not cause any significant symptoms over long periods of time and thus remains inconspicuous, diabetics should consult an ophthalmologist once a year. At the first sign of any deterioration in vision that may be caused by diabetic retinopathy, an eye examination should be performed immediately.

Follow-up

Diabetic retinopathy, a possible secondary disease caused by diabetes mellitus, should be checked regularly by a qualified ophthalmologist in order to detect possible changes in the retina and thus prevent a possible impairment of vision or, in the worst case, blindness. The ophthalmologist uses fundoscopy to look for small aneurysms or hemorrhages that may form in the retinal vessels. If these are detected, it is possible to educate the patient for surgery in which a laser is used to burn certain areas of the retina. This prevents glaucoma (green star), which can be triggered by diabetes mellitus. In addition, the patient should regularly check his sugar in the blood to check the correct setting of the medication and thus prevent further secondary diseases. In addition to the eyes, it is also important to check the kidneys, since a disease of the kidneys also occurs frequently with the eyes. For this purpose, the patient should regularly visit a nephrologist. Furthermore, the diabetic should have his foot checked by his family doctor, since a diabetic foot is not uncommon and can lead to amputation if the condition worsens acutely. Neurological disorders should also be checked and treated by an appropriate specialist.

What you can do yourself

The main triggering factor of diabetic retinopathy is long-standing diabetes mellitus in which blood glucose has not been optimally controlled. Therefore, one of the most important preventive measures is considered to be strict self-monitoring of blood glucose, which should not exceed certain values if possible. This applies to the by far most common diabetes type 2 as well as to the rare genetic autoimmune disease diabetes type 1. The adjustment and orientation of the behavior in everyday life and the application of self-help measures have a great influence on the onset or prevention of diabetic retinopathy. Retinopathy is caused by damage in the walls of blood vessels.This favors the development of microaneurysms, so that after their bursting, hemorrhages occur in the retina – in advanced stages even in the vitreous body – and cause corresponding visual impairments. The most important self-help measures consist of strict control and adjustment of blood glucose and blood pressure, as well as a change in diet to an individually composed diet that facilitates the control of blood glucose levels. In addition, maintaining a normal weight and abstaining from nicotine consumption, as well as limiting alcohol consumption, help prevent retinopathy or slow or even stop the progression of the disease. Following the recommended self-help measures also favors the success of any medical therapies, such as laser treatments to the retina.