Diabetes is an elevated blood sugar level caused by insufficient or ineffective insulin, a hormone secreted by the pancreatic tissue. High blood sugar levels damage the structure of blood vessels, especially the small ones, causing damage. It is divided into two groups: type 1 and type 2. Type 1 diabetes occurs in childhood or adolescence, while type 2 diabetes occurs in adults over 40.

How Does Diabetes Affect the Eye?

In addition to eye diseases, diabetes can affect the whole body because it affects the blood vessels.

The eye is a frequently affected organ because it is rich in small blood vessels. It can damage the blood vessels in the retina, the back layer of the eye, causing diabetic retinopathy. Cataracts develop more frequently and earlier in this patient group. Glaucoma develops more frequently in diabetic patients, and treatment resistance is higher.

What is Diabetic Retinopathy?

Diabetic retinopathy is the most common eye disease related to diabetes and  a major cause of blindness in our country . It occurs as a result of damage to blood vessels in the retina, a light-sensitive tissue at the back of the eye. This can result in fluid leaking out of the blood vessels, causing fluid retention (edema), or abnormal new blood vessels forming on the retina's surface, causing bleeding into the eye.

Both eyes are usually affected. At the beginning of the disease, the patient may have no symptoms. However, half of patients initially examined have varying degrees of diabetic retinopathy, from mild to severe.

This rate increases with the duration of the disease. Therefore, early diagnosis is crucial, as treatment is possible for patients caught early. Therefore, it is beneficial for patients to have an eye exam once a year, even if they have no symptoms.

What are the Stages of Diabetic Retinopathy?

It initially begins as mild, non-proliferative diabetic retinopathy. This is the earliest stage. Bubbles called microaneurysms form in the walls of the retina's small blood vessels. At these points, the vessel walls are weakened, allowing the fluid in the blood to leak out. This can result in small hemorrhages within the retina or accumulations containing various blood elements, called soft and hard exudates. At this stage, vision is not impaired unless the macula, which provides sharp vision, is affected.

However, diabetes has begun to affect the eye and is progressing. It is crucial to detect the disease at this early stage, when vision is still preserved, and to initiate eye diseases and treatments. As the disease progresses, blockages develop in the blood vessels that nourish the retina, from small to large, creating areas of the retina that are not nourished.

Specific chemicals secreted from these areas of impaired nutrition cause the formation of new blood vessels. These blood vessels are structurally abnormal and damaged. Instead of providing nutrition, they cause intraocular hemorrhage, leading to sudden vision loss. This condition is called proliferative or advanced diabetic retinopathy.

 The blood vessels that form during this phase can grow into the clear gel that fills the eye and, over time, cause membranes to form on the surface of the retina, causing shrinkage and damage to the visual cells in the retina. They can also cause increased eye pressure.

As a result of all this, vision loss will inevitably occur, and blindness will develop. Another stage of diabetic retinopathy is called maculopathy. At any stage of the disease, the macula, the area that provides sharp vision, can experience malnutrition or fluid leakage from blood vessel walls.

The leaking fluid causes swelling of the macula and blurring of vision. This condition is called macular edema. Approximately half of patients with proliferative diabetic retinopathy also have macular edema.

How Does Diabetes Cause Bleeding in the Eye?

Diabetes, one of the first symptoms of eye disease, affects the small blood vessels in the retina of the eye, causing bubbles to form on the surface of the vessels. The bubbles disrupt the structure of the blood vessels and allow various blood elements to leak out.

These blood elements leaking into the retina cause superficial hemorrhages, either pinpoint or candle-shaped. Over time, these vessels become blocked, and new blood vessels form in the areas where their blood supply has been compromised. The walls of these vessels are fragile and can bleed easily. This condition is called an intraocular hemorrhage.

Is This Bleeding Temporary?

Hemorrhages within the retina may resolve spontaneously within 1-4 months. However, new hemorrhages are possible. Hemorrhages within the eye can also be absorbed by the body, but as long as unhealthy new blood vessels remain, new hemorrhages are inevitable.

Laser treatment should be performed to reduce the size of the new blood vessels. If the bleeding prevents the retinal layer from being visible and the bleeding persists despite the patient lying upright for a while, a procedure called vitrectomy should be performed to remove the bleeding.

How Are Diabetic Retinopathy and Maculopathy Diagnosed?

Patients who present with eye disease after their vision has decreased often arrive too late. Diabetic eye involvement often presents with no pain or other symptoms. Therefore, even if they have no symptoms, diabetic patients should have an annual eye exam. These patients should undergo a detailed fundus examination with dilated pupils.

After examining the retina through a fundus examination, an angiogram can be performed if necessary to clearly reveal areas of impaired blood flow and new blood vessels. A medication administered through a vein in the arm makes the eye vessels visible, allowing the location of abnormal blood vessels and bubbles causing leaks to be identified.

This procedure is used to diagnose eye diseases and determine the areas to be treated, but it does not have a vasodilator or therapeutic effect.

Another diagnostic method we use is retinal tomography. While eye angiography locates the leak, retinal tomography provides valuable information about the extent of leakage and the cross-section of the retina, especially in cases of maculopathies.

What is done in the treatment?

Early diagnosis is crucial for preventing eye disease. In the mild stages of diabetic retinopathy, treatment is unnecessary unless macular edema is present. Follow-up is sufficient.

Laser therapy is used in advanced-stage diabetes patients, where ischemia is present or abnormal blood vessels are beginning to develop. Laser therapy can prevent blindness in 80% of patients treated in the early stages, when signs of retinopathy begin and vision is still intact.

During laser treatment, a lens placed over the eye creates burns in areas with compromised blood flow. This destroys these areas, preventing the formation of abnormal blood vessels and preventing intraocular bleeding. Because multiple laser treatments are required, the procedure is performed over multiple sessions. The patient may experience some pain during the procedure. The goal of laser treatment is to maintain the patient's vision at the same level as at the time of diagnosis.

Although some temporary loss of vision, color vision, and dark vision may occur after laser treatment,  it is crucial because it prevents more serious vision loss. It's important to remember that the success of laser treatment is directly proportional to the patient's early presentation.

The main risk factor in eye diseases and their treatments is the development of diabetic maculopathy. Because this area is responsible for sharp vision, laser treatment should be limited.

We reduce the amount of fluid accumulation by applying focal or grid lasers to areas of leakage in the retinal tissue surrounding the macula. This usually resolves in a single session.

Another method used to treat macular edema is intraocular medication injections. By blocking and reducing the amount of chemical signals released from areas with compromised blood flow, this prevents edema and new blood vessel formation. This treatment is performed in the operating room. The procedure is very short and can be associated with serious complications. However, because this treatment is temporary, it requires frequent repetitions, and the medications administered are quite expensive.

In cases where intraocular hemorrhage occurs or membranes form on the retina, a surgical treatment called vitrectomy is performed. Even if anatomical success is achieved in patients at this stage, visual improvement is often limited.

What Should Be Done to Protect Eyesight in Diabetes?

If you have diabetes, you should have an eye exam at least once a year to check for eye diseases, even if you have no symptoms. Early diagnosis and prompt intervention are the most important factors in preserving your vision.

Good blood sugar control will prevent the onset of retinopathy and its progression. Therefore, patients should work closely with their internal medicine physician.

Other conditions, such as hypertension and high cholesterol, accelerate the progression of diabetes. Treatment for these conditions is crucial for controlling blood sugar levels.

Diabetic eye findings may progress during adolescence, pregnancy, and when insulin therapy is newly started, and patients should be monitored more closely.