1. What layers do eye tissues consist of?

2. What is retina?

3. What is vitreous? What does it do?

4. Where is the macula (yellow spot) located? What are their duties?

5. What is diabetic retinopathy?

6 . Does diabetes cause blindness?

7. Can diabetic retinopathy and blindness be prevented?

8. Which type of diabetes is most at risk?

9. How often should diabetics have eye examinations?

10. What are the tests used in diabetic retinopathy?

11. How is diabetic retinopathy treated?

12. How is the surgical treatment (vitrectomy) treatment performed at which stage?

DIABETIC RETINOPATHY

Diabetes mellitus (diabetes) is a common metabolic vascular disease that develops due to high blood sugar level (hyperglycemia) resulting from insulin deficiency or ineffectiveness. There are two main types.

Insulin-dependent diabetes: ** Also known as Type I diabetes. It is mostly seen between the ages of 10-20. It usually presents with sudden onset of weight loss, frequent urination, and excessive drinking.** Insulin-independent diabetes: ** Also known as Type II diabetes. It is mostly seen between the ages of 50-70. Although it sometimes occurs with recurrent skin infections, it does not show any symptoms at first.** Since diabetes is a systemic disease, it can cause damage to many organs in the body, such as the eyes, kidneys, vascular and nervous system. Diabetic retinopathy, which is the most common ** _ diabetic retinopathy _ , is the picture that occurs as a result of damage to the retinal layer at the back of the eye that detects light. Diabetic retinopathy is one of the leading causes of blindness in humans.**

Diabetic Retinopathy

Diabetic retinopathy is the damage caused by the deterioration of the nutrition of the nerve layer of the eye, called the retina, which occurs as a result of the destruction of diabetic vessels.

The risk of developing diabetic retinopathy is higher in Type I diabetes than in Type II diabetes. The duration of diabetes is an important factor. When diabetes is diagnosed before the age of 30, the risk of developing diabetic retinopathy is 50% in 10 years and 90% in 30 years. With intensive blood sugar control, the occurrence of diabetic retinopathy can be delayed. In addition, pregnancy triggers the development of diabetic retinopathy. Hypertension and renal failure, if not well controlled, worsen diabetic retinopathy.** The rate of diabetic retinopathy is 45% in patients with diabetes at any level for less than 15 years, while this rate is 62% in patients with a duration of more than 15 years.**

Smoking, high cholesterol, anemia are other important risk factors.

Diabetic retinopathy is the cause of decreased vision or blindness in 90% of diabetic patients. Diabetic retinopathy is one of the most important causes of acquired blindness in developed countries. At least 12% of all blindness in Western countries is due to diabetes.

The basis of the problems that occur in the eye in the initial period of diabetic retinopathy is the increase in the permeability of the retinal vessels, that is, the leakage of some substances in the blood by the vessels. Microaneurysms, hard exudates, retinal edema, and hemorrhages can be seen among the fundus findings of a diabetic patient.

Picture 1: Normal retina ** photograph. Blue arrow indicates macula (yellow dot), which provides sharp central vision, black arrow indicates optic disc (optic nerve).**

_ Picture 2 (a,b): _ Picture above** _ shows the retina of a patient with initial diabetic retinopathy _ **. The black arrow shows some oil-containing substances (hard exudates) in the vein as a result of increased vascular permeability, the white arrow shows the blood leaking out of the vein (microhemorrhages). Diabetes can also disrupt the structure of the vessel wall, causing abnormal enlargements and bubbles (microaneurysms) in the walls. **In the early stages of diabetic retinopathy, patients usually do not have any complaints. However, there may be a decrease in central vision as a result of fluid leakage into the macula (vision center). This condition is called macular edema.

If the blood sugar level remains high and the necessary treatments are not performed, diabetic retinopathy progresses. Vascular changes and occlusions increase and the retina starts to form new vessels that are thinner than normal vessels, can bleed easily and branch very quickly to feed itself. Due to the lack of nutrition, diabetic retinopathy may result in material accumulations (soft exudates) resembling cotton balls, indicating the cessation of conduction in the nerves, formation of new vessels, formation of membranes on the retina as a result of the increase of certain substances, anterior retinal and intra-vitreal hemorrhages.**

Figure 3: Retinal image of advanced diabetic retinopathy . Unlike normal retinal vessels, which are straight, thick and regularly branched, thinner and more fragile new vessels resembling tree branches are indicated by the black arrow. In such cases, ** laser photocoagulation ** is applied in order to prevent new vessel formation and to prevent recurrent vitreous hemorrhages.

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Figure 4: Retinal image with laser treatment ** . The black arrow shows the lighter round marks of the laser where it was made.** Laser photocoagulation does not require hospitalization of the patient. It is done while the patient is sitting and the patient is sent home after the procedure. It is normal to have mild pain and some decrease in vision after laser.

In recent years, argon laser applications have started to be substituted for intravitreal antiVEGF **injections, except for exceptional cases such as retinal traction and tears. After repeated injections, it is possible to treat both macular edema and retinal ischemia in parallel with a regulated blood sugar, as well as to regress retinal and vitreous hemorrhages. Injections can be used as a stand-alone treatment method or in combination with argon laser and vitroretinal surgery.

fundus fluorescein angiography ( FFA ) ** has a very important place in determining diabetes types and planning treatment . A dye is injected into the vein from the patient’s arm. Then, photographs of the fundus are taken at regular intervals while the patient is in a sitting position. The patient does not feel any pain, after which he can go home. It is normal for the skin to turn yellow after the extraction and the urine to be orange. This may take several days. With this examination method, it is possible to detect vascular leakage, occlusion and malnutrition in diabetic patients.

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Figure 5: Normal FFA ** image. There is no bright-colored whiteness of any leakage in the veins or macula.** | |

Figure 6: FFA image of a patient with diabetic retinopathy ** . The bright white color indicated by the black arrow indicates leakage from the vessels.** Due to recurrent vitreous or anterior retinal hemorrhages in very advanced diabetic retinopathy cases, or tractional retinal detachment _ ( retinal detachment from where it should be due to traction) Retinal surgery may be required. Surgery performed in such cases is called pars plana vitrectomy. With Pars plana vitrectomy **, the gel-like fluid (vitreus) inside the eye is removed, the retinal membranes are cleaned and repositioned.

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_ Figure 7: The image shows the retina of a patient with ** ** tractional retinal detachment _ . It is observed that the retina has lost its normal color, the white membranes cover the retinal surface and pull the retina forward (black arrow). In some cases, the retina may not be clearly visible on normal fundus examination. In such cases, an eye ultrasound is performed.

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_ Figure 8: Normal eye ultrasonography image. _ The white arrow indicates the eye fluid (vitreus), the black arrow the retinal layer. | |

_ Figure 9: The following picture shows the eye ultrasonography of a patient with ** ** tractional retinal detachment _ . It is observed that the retina is pulled forward from its normal place and into the eye fluid (black arrows). Another diagnostic method that can be used in patients with diabetic retinopathy is optical coherence tomography (OCT)** . In pathologies such as diabetic macular edema, OCT guides the stage of the disease, indications for treatment and post-treatment follow-ups.**

_ Picture 10 (a,b): The upper left picture (a)** ** shows the normal macula , the right picture (b) shows the OCT image of the macula with cystoid macular edema . Normally, all retinal layers are observed at certain intervals and in certain colors. An edematous macula appears to be filled with cystic black spaces (red arrow). **Every patient with Type I or Type II diabetes is at risk for developing diabetic retinopathy. Every patient with diabetes should have a detailed fundus examination at least once a year. Pregnancy increases the risk of diabetic retinopathy. Therefore, it is recommended that diabetic pregnant women have a fundus examination as soon as possible.

Studies on patients with diabetes show that blood sugar control slows the development and progression of retinopathy. Keeping the blood sugar level within normal limits will reduce the risk of both eye and other organ diseases. Normal blood sugar levels will also reduce the need for laser therapy.**

Private İstanbul Şafak Hospital