Diabetic Macular Oedema (DMO)
Diabetic Macular Oedema (DMO) is a serious complication of diabetic retinopathy, a condition that affects people with diabetes. It occurs when fluid leaks from damaged blood vessels in the retina and accumulates in the macula, the central part of the retina responsible for sharp, detailed vision.
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Dr. Bhaskar Gupta
Consultant Ophthalmologist & Vitreo-Retinal Specialist
20+ years experience
Description
Diabetic Macular Oedema (DMO) is a serious complication of diabetic retinopathy, a condition that affects people with diabetes. It occurs when fluid leaks from damaged blood vessels in the retina and accumulates in the macula, the central part of the retina responsible for sharp, detailed vision. The macula is crucial for tasks like reading, recognizing faces, and driving. This fluid accumulation causes the macula to swell, leading to blurred or distorted vision. DMO is a leading cause of vision loss among working-age adults with diabetes. The damage to the blood vessels in the retina is a direct consequence of prolonged high blood sugar levels, which can weaken the vessel walls, making them permeable and prone to leakage. The inflammatory response triggered by these damaged vessels further contributes to the oedema, creating a vicious cycle of damage and fluid accumulation. Early detection and treatment are paramount to preserving vision and preventing irreversible damage.
Causes
Why it happens ?
- Microaneurysms: Small bulges form on the blood vessel walls.
- Leakage: These damaged vessels become leaky, allowing fluid, fats, and proteins to seep into the surrounding retinal tissue, particularly the macula.
- Ischemia: In some cases, the blood vessels can become completely blocked, leading to a lack of oxygen supply to parts of the retina. This can trigger the growth of new, abnormal, and fragile blood vessels (neovascularization), which are even more prone to leakage and bleeding.
- Inflammation: The damaged blood vessels and the presence of leaked fluid trigger an inflammatory response in the retina, further contributing to the swelling.
- Vascular Endothelial Growth Factor (VEGF): High levels of VEGF are produced in diabetic retinopathy, especially in response to retinal ischemia. VEGF is a potent signaling protein that promotes the growth of new blood vessels and increases the permeability of existing ones, exacerbating fluid leakage.
Incidence
The incidence of DMO is directly related to the duration and control of diabetes. Approximately one in three people with diabetes will develop diabetic retinopathy, and a significant percentage of these individuals will progress to DMO. Studies show that about 7% of all people with diabetes will develop DMO. The risk increases with longer duration of diabetes, poor glycemic control (high HbA1c levels), high blood pressure, and high cholesterol. Certain ethnic groups, such as African Americans and Hispanic/Latino individuals, also have a higher prevalence of DMO. It can affect people with both Type 1 and Type 2 diabetes, though it is more common in Type 2 diabetes due to its higher prevalence. Regular eye screenings are crucial for all diabetic patients, regardless of their perceived vision, as DMO can be present even without noticeable symptoms in its early stages.
Symptoms
In its early stages, DMO can be asymptomatic, meaning individuals may not experience any noticeable vision changes. As the condition progresses and the swelling in the macula increases, symptoms typically begin to appear. These can include:
Blurred or wavy central vision
This is often the most common symptom, making it difficult to read, drive, or recognize faces.
Distorted vision (metamorphopsia)
Straight lines may appear bent or wavy.
Colours appearing faded or washed out
The macula is also responsible for colour perception, and swelling can affect this.
Difficulty seeing in low light
Reduced contrast sensitivity can make it challenging to see in dim environments.
Presence of a dark or empty spot in the center of vision
This occurs as the macula's function is significantly impaired.
Treatment Options
The goal of DMO treatment is to reduce macular swelling, prevent further vision loss, and, in some cases, improve vision. Treatment options have significantly advanced in recent years:
Anti-VEGF Injections
These are currently the first-line treatment for most cases of DMO. Medications such as ranibizumab, aflibercept, and bevacizumab are injected directly into the vitreous humour (the gel-like substance that fills the eye). These drugs block the action of VEGF, thereby reducing fluid leakage and abnormal blood vessel growth. Multiple injections, often given monthly initially, are usually required.
Steroid Injections/Implants
Corticosteroids (e.g., triamcinolone acetonide, fluocinolone acetonide implant) can also be injected into the eye to reduce inflammation and swelling. They are often used when anti-VEGF treatments are ineffective or in certain specific cases. Steroid implants can provide a longer-lasting effect.
Laser Photocoagulation (Focal or Grid Laser)
This traditional treatment involves applying precise laser burns to leaky blood vessels in the macula to seal them off and reduce fluid leakage. While less commonly used as a primary treatment since the advent of anti-VEGF, it can still be beneficial for specific types of DMO or in combination with other therapies.
Vitrectomy
In rare cases, if there is significant traction on the macula from scar tissue or vitreous haemorrhage, a surgical procedure called vitrectomy may be performed to remove the vitreous gel and relieve the traction.
Blood Sugar and Blood Pressure Control
Regardless of specific eye treatments, strict control of blood sugar levels (HbA1c), blood pressure, and cholesterol is fundamental to managing DMO and preventing its progression. This involves diet, exercise, and appropriate medication.