Can diabetic retinopathy be treated

Diabetic retinopathy

What is diabetic retinopathy?

Long-term increased sugar concentrations in the blood damage the blood vessels, including the small vessels of the retina. The sugar changes and destroys the walls of the small vessels, which makes them more permeable or can burst. Damage to the retina is caused by bleeding, accumulation of fluid and the formation of new blood vessels.

About 5 percent of the population in Germany have diabetes . Of these, more than 20 percent suffer from diabetic retinopathy. A diet high in carbohydrates and fat increases the number of type 2 diabetics. Diabetic retinopathy is also gaining in importance. It is the leading cause of blindness in people between the ages of 20 and 65 in Europe and North America.

How does diabetic retinopathy develop?

Diabetic retinopathy is caused by a disease of the small blood vessels in the retina (microangiopathy). Increased sugar concentrations in the blood damage the small blood vessels in the retina, making them more permeable and brittle. Liquid escapes from the permeable vessels.

With the liquid, fat and protein also get out of the vessels and are deposited in the retina. If small vessels burst, bleeding into the retina occurs. Deposits thicken and harden the damaged vessel walls (vascular sclerosis). This causes the vessels to constrict. Less blood flows through the small vessels of the retina and the retina receives less oxygen. The thickened walls can even completely close off the smallest vessels, the capillaries. To compensate for the lack of oxygen, the retina tries to form new vessels. To do this, it produces growth factors (VEGF, vascular entothelial growth factor) that stimulate the formation of new blood vessels.

The new vessels emanate from the small veins, the venules, and the retina and grow fan-shaped into the retina and the vitreous humor. These newly formed vessels are more fragile than normal blood vessels. They burst easily and there can be serious bleeding into the vitreous humor. The growth of the vessels into the vitreous also creates a pull on the retina. This pull can detach the retina from its base, the choroid.

Macular edema is a complication of diabetic retinopathy. Fluid that has leaked from permeable vessels collects in the central area of ​​the retina, the macula, causing this area to swell.

Another problem can arise if VEGF gets into the anterior segment of the eye with the aqueous humor and stimulates the formation of new vessels in the iris. The newly formed vessels can close the chamber angle. The aqueous humor can then no longer drain and a secondary one glaucoma arises.

How are visual disorders manifested in diabetes?

At first, the patient hardly notices any deterioration in vision. Only when the disease progresses does he perceive impaired vision. This can be visual impairment, distorted vision or blind spots. The perception of flashes of light, black dots and shadows can also be symptoms of retinal disease.

Macular edema can suddenly severely impair vision, because the macula is the central point of the retina and the area of ​​sharpest vision. The deterioration in vision ranges from reduced reading ability to extensive blindness. Vitreous hemorrhage also leads to an acute deterioration in vision. The patient's vision is blurred, as if through a veil. In the worst case, the patient can get through a Retinal detachment go blind.

Stages of diabetic retinopathy

Diabetic retinopathy is divided into the following stages:

  1. Mild non-proliferative diabetic retinopathy : The patient usually has no visual disturbances. During the examination, the ophthalmologist noticed slight changes in the retina. These can be fine bulges in the small blood vessels (microaneurisms), small punctiform hemorrhages and fat deposits in the retina. The changes are reversible at this stage.
  2. Severe non-proliferative diabetic retinopathy: The changes in the retina are clear. Multiple haemorrhages in the retina, blurred whitish yellow spots, thickening of the small veins, vascular changes and retinal areas without vascular supply are typical findings during an eye examination. No newly formed vessels are visible yet. The patient may experience visual disturbances, especially when the changes occur in the macular area. In about half of the cases, this form develops into the proliferative form within a year.
  3. Proliferative Diabetic Retinopathy: Newly formed vessels are now added to the existing changes. This can lead to complications in the form of vitreous hemorrhage and retinal detachment. Multiple bleeding into the vitreous usually cannot recede. The proliferative form is more common in type 1 diabetes. Proliferative retinopathy develops faster, especially during pregnancy and puberty.
  4. Diabetic macular apathy: Macular apathy (disease of the macula) is a complication that can also occur. Fluid from leaky vessels collects in the central area of ​​the retina, the macula, causing this area to swell (macular edema). The swelling increases the circulatory disturbance in the retina, which is already poorly supplied with blood. During the examination, the ophthalmologist will see fatty deposits and a thickening in the middle of the macula. Central visual cells can be destroyed by macular edema. The patient's eyesight can deteriorate dramatically due to macular apathy.

How is diabetic retinopathy treated?

Good control of diabetes is the best way to stop diabetic retinopathy for as long as possible. The better the patient's blood sugar control, the later the retinopathy occurs. Risk factors that promote the progression of diabetic retinopathy are considered Obesity , Smoking, high blood pressure and hyperlipidemia (increased blood lipids). Patients should take care to manage these factors.

Treating diabetic retinopathy is not straightforward. There is no causal drug therapy. Mild diabetic retinopathy is therefore not yet treated. However, there are effective methods of reducing the symptoms of severe retinopathy and stopping the formation of new blood vessels.

Steroids or antibodies against VEGF can be injected directly into the vitreous humor (intravitreal injection). They inhibit the formation of new vessels in the retina. There is also the option of obliterating blood vessels in the retina with the laser.

The panretinal laser coagulation is used for the therapy of proliferative diabetic retinopathy. With the treatment, the progression of the formation of new vessels is stopped and thus the risk of vitreous hemorrhage and retinal detachment is significantly reduced. The ophthalmologist obliterates the outermost layer of the retina with a grid of 1000 to 2000 very small individual foci of coagulation. The macula, the area of ​​sharpest vision, is left out. Only the outermost layer of the retina is treated, the nerve fibers underneath remain intact. In this way, the eyesight is largely preserved, but as a result of the therapy the field of vision can be restricted and color vision and adaptation to darkness can be disturbed. The ophthalmologist can also use this method for severe diabetic retinopathy when new blood vessels have not yet formed to prevent new blood vessels from forming.

For the treatment of macular edema, the focal laser coagulation . The ophthalmologist obliterates the microaneurisms and places where the fluid leaks with the laser. Before the procedure, the ophthalmologist examines the fundus with fluorescence angiography. Fluorescence angiography is an imaging procedure that makes the leaks in the vessels visible. The ophthalmologist obliterates these areas in order to stop the leakage of fluid. Edema and fat deposits recede. This can improve visual acuity again. In addition, the ophthalmologist can inject steroids or antibodies against VEGF into the vitreous humor.

If the vitreous hemorrhage persists, especially if there is an additional detachment of the retina, the ophthalmologist must surgically remove the vitreous. The surgical removal of the vitreous is referred to as Vitrectomy . Usually the vitreous is replaced with a solution. The retina is carefully separated from the vitreous humor. Sometimes a silicone oil or a gas is needed to press the retina back onto its surface.

Course and prognosis of diabetic retinopathy

The course of the disease is strongly dependent on the blood sugar control and the duration of the disease. In the first few years of diabetes, there are usually no changes in the retina. In type 1 diabetes, it takes at least 5 years for the first changes in the retina to be visible, usually after 10 to 13 years. However, after 20 years of diabetes, up to 90 percent of diabetics develop diabetic retinal disease.

Timely, stage-adapted treatment is crucial for the prognosis. If laser coagulation is done early enough, vision can usually be preserved. There are often only a few weeks between the first appearance of newly formed vessels and vitreous hemorrhage. It is therefore extremely important to have regular check-ups by an ophthalmologist. Patients with type 1 diabetes should have their eyes examined once a year for 5 years after the onset of diabetes. More frequent checks are necessary after 10 years. Check-ups should be carried out every three months during puberty and pregnancy. Patients with type 2 diabetes should see an ophthalmologist at least once a year, and every 3 months for severe retinopathy.

Complications of diabetic retinopathy, such as vitreous hemorrhage, retinal detachment and neovascularization in the anterior segment of the eye, still sometimes lead to blindness today. However, serious consequences can be prevented through good blood sugar control, regular check-ups by the ophthalmologist and laser treatment adapted to the stage. Then the chance of vision loss is less than 5 percent.

Literature:

  • Grehn. F. (2012). Ophthalmology, 31st revised edition, Springer Verlag 2012
  • Professional Association of Ophthalmologists in Germany (2011). Guideline No. 20 - Diabetic Retinopathy Link: https://augeninfo.de/leit/leit20.pdf (23.11.2020)
  • Professional Association of Ophthalmologists in Germany e.V. Retinal Diseases. Link: https://augeninfo.de/cms/hauptmenu/augenheilkunde/augenwohlungen/netzhautverbindungen.html (23.11.2020)
  • Professional Association of Ophthalmologists in Germany (2012). Patient Brochure Sugar-Related Retinal Disease. Link: https://augeninfo.de/cms/fileadmin/pat_brosch/diabetes.pdf (23.11.2020)