The cause of diabetic retinopathy

 

In recent years, diabetes has been regarded as one of the major chronic diseases, along with hypertension and cardiovascular disease. Due to the westernization of dietary habits, lack of exercise, increased stress, and rising rates of obesity, the number of diabetes patients worldwide has been steadily increasing — with the proportion in Asia also growing significantly.

It is easy to think of diabetes as a condition that only affects blood sugar control, but in reality, it is a highly complex disease that can cause various complications throughout the body. Among these, one of the most serious complications threatening vision is diabetic retinopathy. This condition is a severe eye disease that can lead to blindness, and it is an issue that every diabetes patient should pay close attention to.

▲ (a) Healthy retina (b) Diabetic retinopathy

1. Why the Retina Becomes Damaged
   Diabetic retinopathy, as the name suggests, is damage to the retinal blood vessels caused by diabetes. The retina is a layer of tissue located deep inside the eye that detects light and transmits visual information to the brain. It is surrounded by a network of very fine blood vessels, and when blood sugar levels remain high for a long period due to diabetes, these tiny vessels gradually become damaged, leading to the onset of the disease.

When high blood sugar persists, inflammatory responses occur in the endothelial cells of the blood vessels, and oxidative stress increases. As a result, the vessel walls weaken, normal blood circulation is disrupted, and blood vessels may become blocked or leak blood components into surrounding tissues. Over time, these subtle changes accumulate and eventually develop into a condition that affects vision.

A particularly concerning aspect of this damage is that it progresses slowly without noticeable symptoms. In other words, by the time a patient begins to notice vision problems, significant retinal damage has often already occurred. Therefore, anyone diagnosed with diabetes should undergo regular ophthalmic examinations, even if no symptoms are present.

▲ Neurovascular unit and the process of retinal destruction caused by diabetes

2. The Relationship Between the Progression of Diabetes and Retinal Damage
   Diabetic retinopathy tends to occur more frequently in patients who have had diabetes for a longer period. For example, within five years of diagnosis, less than 30% of patients show signs of retinopathy, but after more than 15 years with the disease, the rate exceeds 70%.

In cases where diabetes is diagnosed at a young age, the progression of the disease can be clearly monitored, allowing early detection of retinal changes through regular fundus examinations. On the other hand, for those who develop diabetes in adulthood, it is often difficult to pinpoint when high blood sugar began. Therefore, regular retinal check-ups are even more essential starting from the time of diagnosis.

This condition is broadly classified into non-proliferative and proliferative diabetic retinopathy.

In the early, non-proliferative stage, the vessel walls weaken, and small exudates or microhemorrhages appear in the retina, though there are typically no noticeable symptoms. As the disease progresses, however, new abnormal blood vessels (neovascularization) begin to form. These vessels are extremely fragile and prone to rupture or bleeding. This advanced stage is known as proliferative diabetic retinopathy, and in severe cases, it can lead to vitreous hemorrhage or retinal detachment, significantly increasing the risk of blindness.


3. Methods for Diagnosing Diabetic Retinopathy

These tests are selectively performed depending on the patient’s condition, and combining multiple methods allows for a more accurate diagnosis and treatment plan. Additional examinations may also be conducted if necessary.

▲ Vitrectomy Procedure

4. Prevention Is More Important Than Treatment

The most crucial factor in preventing the progression of diabetic retinopathy is strict blood sugar control. Keeping blood sugar within a stable range can significantly slow the advancement of retinopathy, and managing blood pressure and lipid levels simultaneously provides even more effective prevention.

However, blood sugar control alone cannot completely prevent the disease, so regular eye examinations are essential. For diabetes patients, an ophthalmologic check-up at least once a year is recommended, and even in the absence of symptoms, routine fundus examinations should be consistently performed.

Lifestyle improvements also play an important role in prevention. Smoking and alcohol consumption can accelerate vascular damage and should be avoided, while a diet rich in vitamins and antioxidants, regular exercise, and proper sleep management can be beneficial.

Diabetic retinopathy is not merely a secondary complication of diabetes; if not detected early, it can lead to severe vision loss. The primary cause of this condition is microvascular damage due to poor blood sugar control, but other factors—such as disease duration, lifestyle habits, and individual physical conditions—also contribute.

Just as diabetes requires lifelong management, retinal conditions resulting from it also demand continuous attention and monitoring. The eyes are invaluable organs, and once vision is lost, it cannot be restored. Therefore, it is strongly recommended to begin proactive eye care from the moment of a diabetes diagnosis.