Diabetic Retinopathy Stages: Understanding the International Classification and Progression
Diabetic retinopathy is a serious complication of diabetes that affects the eyes, potentially leading to vision loss if not detected and treated early. Recognized globally, the International Clinical Diabetic Retinopathy Severity Scale categorizes the disease into six distinct stages. These stages help healthcare providers assess disease progression, determine appropriate treatment plans, and improve patient outcomes. Understanding each phase is crucial for early intervention and preserving long-term eye health.
The Six Stages of Diabetic Retinopathy
The condition progresses gradually, with each stage reflecting an increase in retinal damage caused by prolonged high blood sugar levels. The classification system divides the disease into non-proliferative (early) and proliferative (advanced) phases, providing clarity on severity and guiding clinical decisions.
Stage I: Mild Non-Proliferative Diabetic Retinopathy
In the earliest stage, small areas of balloon-like swelling in the retina's tiny blood vessels, known as microaneurysms, begin to appear. There may also be minor bleeding in the retina. At this point, most patients experience no noticeable symptoms or changes in vision. Because signs are subtle, regular eye screenings are essential—especially for individuals managing diabetes—to catch changes before they advance.
Stage II: Moderate Non-Proliferative Diabetic Retinopathy
As the disease progresses, more microaneurysms form, and mild retinal abnormalities become visible during an eye exam. Hard exudates—deposits of fats and proteins leaking from damaged vessels—may appear. Some people report mild visual disturbances such as floaters, which look like spots or thread-like strands drifting across their field of vision. While these symptoms may seem harmless, they signal underlying vascular damage that requires monitoring and better glycemic control.
Stage III: Severe Non-Proliferative Diabetic Retinopathy
This stage marks a critical turning point. Multiple hemorrhages and cotton wool spots (soft exudates), which indicate areas of blocked blood flow in the retina, become widespread. Blood vessels begin to close off, depriving parts of the retina of oxygen—a condition called retinal ischemia. Patients may notice blurred vision or increased floaters. Without proactive management, including tighter blood sugar, blood pressure, and cholesterol control, the risk of advancing to proliferative stages rises significantly.
Advanced Stages: Proliferative Diabetic Retinopathy
Stages IV through VI are classified as proliferative diabetic retinopathy (PDR), characterized by the growth of abnormal new blood vessels. This neovascularization is the body's flawed attempt to compensate for poor oxygen supply but ultimately leads to severe complications.
Stage IV: Early Proliferative Diabetic Retinopathy
New, fragile blood vessels start forming along the retina and into the vitreous gel inside the eye. These vessels are prone to leakage and can cause vitreous hemorrhage, leading to sudden vision blurring or partial vision loss. Even at this stage, some patients may not feel pain, masking the seriousness of the condition. Diagnostic tools like fluorescein angiography and optical coherence tomography (OCT) are vital for accurate assessment.
Stage V: High-Risk Proliferative Diabetic Retinopathy
The newly formed blood vessels become increasingly fibrotic, meaning scar tissue begins to develop alongside them. This fibrosis can contract over time, exerting traction on the retina. Vision deteriorates further due to persistent bleeding, fluid accumulation, and structural distortion of the retina. Treatment options such as panretinal photocoagulation (PRP) laser therapy are typically recommended to reduce abnormal vessel growth and prevent detachment.
Stage VI: Advanced Proliferative Diabetic Retinopathy with Retinal Detachment
In the most severe stage, extensive fibrovascular proliferation pulls the retina away from the back of the eye, resulting in tractional retinal detachment. Once this occurs, significant and often permanent vision loss follows. Surgical intervention, such as vitrectomy, may be attempted, but success rates are limited, especially if detachment has been present for some time. Unfortunately, many patients in Stage VI face irreversible blindness, underscoring the importance of early detection and consistent eye care.
Non-Proliferative vs. Proliferative Phases: Key Differences
Stages I to III fall under non-proliferative diabetic retinopathy (NPDR), where damage is largely internal and asymptomatic. In contrast, Stages IV to VI represent proliferative diabetic retinopathy (PDR), involving dangerous new blood vessel formation and structural complications. The transition from NPDR to PDR indicates a major escalation in disease severity.
Early diagnosis is paramount. Routine comprehensive dilated eye exams—at least once a year for people with diabetes—are the best defense against advanced retinopathy. Managing systemic factors like HbA1c levels, hypertension, and dyslipidemia plays a critical role in slowing progression. With timely intervention, even those in moderate stages can maintain functional vision for years.
Ultimately, awareness and proactive healthcare are the strongest tools in combating diabetic eye disease. By understanding the international staging system and adhering to preventive strategies, patients and clinicians can work together to protect sight and improve quality of life.