Macular oedema is a condition where fluid builds up in the macula, the central part of the retina at the back of your eye, causing it to swell and potentially affecting your ability to see clearly and perform everyday tasks like reading or driving.

What is Macular Oedema?

Macular oedema, also spelled macular edema, describes swelling that occurs in a specific area of your eye called the macula. Your retina is a thin layer of tissue lining the back of your eye that captures light and helps you see. The macula sits right in the center of your retina and plays a crucial role in your vision because it controls your sharpest, most detailed sight—the kind you need when you’re reading small print, recognizing someone’s face across a room, or safely operating a vehicle.^[1]

When the macula becomes swollen with fluid, it’s similar to a blister forming on your skin after a burn. This swelling distorts the normal structure of the retina, making it harder for light signals to be properly processed and sent to your brain. The fluid accumulation typically happens when blood vessels in or near the macula become damaged or abnormal and start leaking fluid into the surrounding tissue. This leakage causes the macula to thicken and swell, which interferes with your ability to see clearly.^[2]

The condition itself is not a disease but rather a symptom or complication of various underlying eye conditions or health problems. Think of it as a warning sign that something else in your body or eyes needs attention. The severity of macular oedema can vary widely from person to person—some people experience only mild blurriness, while others face more serious central vision loss that significantly impacts their daily activities.^[1]

Symptoms of Macular Oedema

The most common symptom of macular oedema is blurry vision that tends to worsen gradually over time. This blurriness primarily affects your central vision—what you see when you look straight ahead at something. Because the macula is responsible for detailed vision, you might first notice difficulties with tasks that require precision, such as threading a needle, reading fine print in books or on medicine labels, or recognizing facial features.^[2]

Many people with macular oedema notice that straight lines appear wavy or distorted, especially when looking directly at them. For example, the edge of a door frame or lines on a page might seem to bend or curve when they should be straight. This distortion, known medically as metamorphopsia, occurs because the swollen macula disrupts the normal processing of visual information.^[3]

Colors may also appear less vibrant than usual—what once looked bright and vivid might now seem dull, faded, or washed out. Some people describe it as looking at the world through a slightly dirty window. You might also notice that objects appear to be different sizes when you compare what you see with one eye versus the other, or you may develop dark or blank spots in your central field of vision, called scotomas.^[1]

If you have macular oedema in only one eye, you might not notice these changes right away because your other eye compensates for the vision loss. This is why it’s important to occasionally check each eye separately—cover one eye and look at straight lines or text, then repeat with the other eye. Any differences between what the two eyes see should prompt a visit to an eye care professional.^[1]

Causes of Macular Oedema

Macular oedema develops when blood vessels in or around the macula become damaged or abnormal and begin leaking fluid. Several different medical conditions can cause this blood vessel damage, making macular oedema a complication of these underlying problems rather than a standalone disease.^[1]

The most common cause is diabetic retinopathy, an eye condition that affects people with diabetes. When blood sugar levels remain high over time, they can damage the small, delicate blood vessels throughout your body, including those in your eyes. These damaged vessels may swell and leak fluid and proteins into the macula. When diabetic retinopathy leads to macular swelling, doctors call it diabetic macular oedema, or DME. This is one of the leading causes of vision loss among people with diabetes.^[1]

Another common cause is age-related macular degeneration, particularly the “wet” type, also called neovascular AMD. In this condition, abnormal blood vessels grow beneath the macula. These new vessels are fragile and prone to leaking fluid or blood into or under the retina, which causes swelling. While age-related macular degeneration is more common in older adults, the wet form specifically can lead to significant macular oedema.^[1]

Retinal vein occlusion occurs when veins carrying blood away from the retina become blocked. When this happens, blood cannot drain properly and backs up, causing it to leak into the macula and create swelling. This blockage is often associated with high blood pressure, high cholesterol, or diabetes.^[1]

Eye surgery, particularly cataract surgery, can sometimes lead to macular oedema. This type of swelling that develops after surgery is often called Irvine-Gass syndrome or cystoid macular oedema. While the swelling is typically mild, it still requires treatment to prevent long-term vision problems.^[1][7]

Uveitis, which is inflammation inside the eye, can also cause macular swelling. This inflammation happens when your immune system mistakenly attacks tissues in your eye. It can affect any part of the eye, including the macula, causing fluid accumulation and swelling.^[1]

Less common causes include genetic conditions like retinitis pigmentosa, trauma to the eye, and certain medications. Some medicines used to treat glaucoma or diabetes can cause macular oedema as a side effect. Even inflammation following eye trauma can trigger swelling in the macula.^[1][2]

Risk Factors for Macular Oedema

Several factors increase your likelihood of developing macular oedema. Understanding these risk factors can help you take preventive measures and remain vigilant about your eye health.

Having diabetes is one of the strongest risk factors. If your blood sugar levels are poorly controlled over time, you face a higher risk of developing diabetic retinopathy and subsequent macular oedema. The longer you’ve had diabetes, especially if it’s not well managed, the greater your risk becomes. Both type 1 and type 2 diabetes can lead to these eye complications.^[4]

High blood pressure, also known as hypertension, increases your risk significantly. Elevated blood pressure damages blood vessels throughout your body, including the tiny vessels in your eyes. When combined with diabetes, high blood pressure can accelerate eye damage and make macular oedema more likely.^[7]

If you’ve had eye surgery, particularly for cataracts, you have an increased risk of developing macular oedema afterward. Certain pre-existing conditions like retinal vein occlusion, uveitis, epiretinal membrane, macular hole, or retinitis pigmentosa can further elevate this risk when combined with surgery.^[5]

Age plays a role as well, especially regarding age-related macular degeneration. As you get older, your risk of developing the wet form of macular degeneration increases, which in turn raises your likelihood of experiencing macular oedema.^[3]

Certain medications, including some used to treat glaucoma or diabetes, as well as vitamin B3 supplements in high doses, can increase your risk. If you already have macular oedema in one eye, you’re more likely to develop it in the other eye as well.^[5]

Lifestyle factors matter too. Smoking, being overweight, and having heart disease all contribute to blood vessel damage and can increase your risk of macular oedema. These factors often work together—for example, smoking combined with diabetes creates a compounded risk that’s greater than either factor alone.^[3]

Prevention of Macular Oedema

While you cannot always prevent macular oedema entirely, especially when it’s related to genetic conditions or unavoidable factors like aging, you can take several important steps to reduce your risk and protect your vision.

If you have diabetes, managing your blood sugar levels is absolutely critical. Keeping your blood glucose within your target range helps protect the blood vessels in your eyes from damage. This means monitoring your blood sugar regularly, taking medications as prescribed, following your meal plan, and staying physically active. Even modest improvements in blood sugar control can make a meaningful difference in reducing your risk of diabetic macular oedema.^[1]

Controlling your blood pressure is equally important, whether or not you have diabetes. High blood pressure damages blood vessels throughout your body, including those in your retina. Aim to keep your blood pressure within the recommended range through medication if prescribed, limiting salt intake, maintaining a healthy weight, exercising regularly, and managing stress. Losing even a modest amount of weight can help lower blood pressure significantly.^[7]

Regular eye examinations are one of your best defenses against vision loss from macular oedema. If you have diabetes, you should have a comprehensive dilated eye exam at least once a year—or more often if recommended by your eye doctor. These exams allow your doctor to detect early signs of retinal damage before you notice any symptoms. Early detection and treatment can prevent macular oedema from developing or worsening.^[1]

Adopting a healthy lifestyle benefits your eyes along with the rest of your body. This includes eating a balanced diet rich in fruits, vegetables, whole grains, and fish, which may support retinal health. Regular physical activity—at least 150 minutes of moderate exercise per week—improves blood flow to the retina and helps control blood sugar and blood pressure.^[7]

Quitting smoking is crucial. Nicotine damages blood vessels and worsens diabetes, accelerating eye problems that can lead to macular oedema and potentially blindness. If you smoke, talk to your doctor about strategies and resources to help you quit.^[17]

If you’re scheduled for eye surgery, discuss your risk factors with your surgeon beforehand. Make sure your doctor knows about any pre-existing conditions like diabetes, uveitis, or previous retinal problems. Understanding your personal risk can help your medical team take appropriate precautions and monitor you more closely after the procedure.^[5]

How Macular Oedema is Diagnosed

Diagnosing macular oedema involves several tests that allow your eye doctor to examine the retina and macula in detail. The good news is that these tests are generally painless and non-invasive.

Your eye doctor will typically start with a dilated eye exam. During this simple procedure, they place special eye drops in your eyes to widen (dilate) your pupils. This allows them to see more of the inside of your eye, including the retina and macula. Using special instruments and lenses, they can look for signs of swelling or fluid accumulation.^[1]

If your doctor suspects macular oedema based on the dilated exam, they may perform additional tests to confirm the diagnosis and determine its severity. An optical coherence tomography scan, or OCT, has become one of the most valuable tools for diagnosing macular oedema. This non-invasive test uses special light waves to create high-resolution, cross-sectional images of your retina, almost like taking a photograph of a slice through your eye. The OCT can show the layers of your retina in great detail and reveal areas where fluid has accumulated. It can even measure exactly how thick the macula has become due to swelling—normal macula thickness is less than 500 microns, but swelling can cause it to exceed this measurement.^[2][5]

Another diagnostic tool is fluorescein angiography. For this test, your doctor injects a special fluorescent dye into a vein in your arm. The dye travels through your bloodstream to the blood vessels in your eye. As it flows through these vessels, a special camera takes photographs that show which blood vessels are leaking fluid. This test helps your doctor identify exactly where the leakage is occurring and how severe it is.^[1]

Sometimes doctors use a combination of these tests to get the most complete picture of what’s happening in your eye. Your optometrist or ophthalmologist might initially detect or suspect macular oedema during a routine exam using a slit lamp—a specialized microscope used to examine the eye. They can then confirm the diagnosis and develop a treatment plan based on the additional imaging tests.^[2]

Treatment Options for Macular Oedema

Treatment for macular oedema focuses on reducing the swelling and preventing further vision loss. The specific treatment approach depends on what’s causing the oedema, how severe it is, and how much it’s affecting your vision. In many cases, treating the underlying condition that caused the oedema is an essential part of the overall treatment strategy.

Eye injections are one of the most common treatments. These involve injecting medication directly into the gel-like substance that fills your eye, called the vitreous. While this might sound uncomfortable, the procedure is typically quite painless because your doctor numbs your eye beforehand. The medications used in these injections fall into different categories depending on the cause of your macular oedema.^[2]

Anti-VEGF medications block a protein called vascular endothelial growth factor, which promotes the growth of abnormal blood vessels that leak fluid. By blocking this protein, anti-VEGF drugs help reduce leakage and swelling. Common anti-VEGF medications include aflibercept (Eylea), bevacizumab (Avastin), and ranibizumab (Lucentis). These injections are typically given once a month initially, often for the first six months, and then the frequency is gradually reduced based on how your eyes respond.^[2][9]

Corticosteroid medications, which are powerful anti-inflammatory drugs, can also be injected into the eye or implanted as a slow-release device. One such medication is Ozurdex, which has been approved for treating macular oedema caused by retinal vein occlusion and inflammation at the back of the eye. Steroid eye drops may be prescribed for some types of inflammation-related oedema. However, steroids are generally not the first choice because they can lead to complications like cataracts or glaucoma.^[2][5]

For certain causes of macular oedema, such as those associated with inherited retinal diseases like retinitis pigmentosa, medications taken as eye drops or tablets may be helpful. Dorzolamide eye drops (Trusopt) or acetazolamide tablets are sometimes prescribed for these specific types of oedema.^[2]

Laser treatment is another option. During focal-grid macular laser surgery or photocoagulation, your doctor uses a laser to seal leaking blood vessels and reduce swelling. The laser creates small burns that stop the leaks. This procedure is often performed in conjunction with anti-VEGF injections if the injections alone aren’t fully effective. Typically, only one eye is treated at a time to allow proper healing before treating the other eye.^[4][9]

In more severe or complicated cases, surgery may be necessary. A vitrectomy involves removing the gel-like vitreous from inside your eye, along with any blood vessels, blood, or scar tissue that might be contributing to the problem. This is typically reserved for cases where other treatments haven’t worked or when there are additional complications.^[4][5]

It’s important to understand that treatment often requires patience and persistence. Healing can take weeks or months, and many people need ongoing treatment for years to maintain their vision improvements. Some people notice vision improvements shortly after starting treatment, while others may see more gradual changes. With consistent treatment and follow-up care, many people are able to stabilize their vision or even regain some sight that was lost.^[11]

Pathophysiology: How Macular Oedema Develops

Understanding what happens inside your eye when macular oedema develops can help you appreciate why certain treatments work and why managing underlying conditions is so important.

Your retina functions somewhat like the film in a camera—it captures images and sends them to your brain for processing. The macula, located in the center of the retina, is densely packed with specialized cells called photoreceptors that detect light and are responsible for your sharpest vision. For these cells to work properly, the retina must maintain its normal structure and thickness.^[12]

Blood vessels supply oxygen and nutrients to the retina while carrying away waste products. In a healthy eye, these vessels have tight junctions that prevent fluid from leaking out into the surrounding tissue. The retina also has natural mechanisms to absorb small amounts of fluid that might seep out from normal processes.^[12]

Macular oedema develops when this delicate balance is disrupted. Various conditions can damage the blood vessels in and around the retina, causing them to become weak, abnormally permeable, or to develop weak, bulging areas called microaneurysms. When this happens, fluid, proteins, and sometimes blood leak from these damaged vessels into the surrounding retinal tissue.^[12]

If more fluid leaks into the macula than the retina can absorb and clear away, the excess fluid accumulates, causing the tissue to swell. Think of it like a lawn after heavy rain—if more water falls than the ground can absorb, puddles form. In the retina, these “puddles” of fluid create blisters that distort the normal layered structure of the macula. Sometimes the fluid forms many small pockets arranged in a pattern resembling a honeycomb, which is why this type is called cystoid macular oedema.^[12]

This swelling physically distorts the photoreceptors and other cells in the macula, interfering with their ability to properly capture and process light. It’s similar to trying to take a clear photograph with water droplets on the camera lens—the droplets distort the image. In your eye, this distortion translates into the blurry, wavy, or incomplete vision that characterizes macular oedema.^[12]

In conditions like diabetic retinopathy, chronic high blood sugar damages the walls of blood vessels, making them weak and leaky. In wet age-related macular degeneration, abnormal new blood vessels grow beneath the retina—these vessels are inherently fragile and almost always leak. In retinal vein occlusion, a blocked vein causes blood to back up and pressure to build, forcing fluid out of the vessels. In each case, the end result is excess fluid accumulating in the macula.^[12]

When inflammation is involved, such as with uveitis or after surgery, inflammatory cells and chemical signals cause blood vessels to become more permeable, allowing fluid to escape more easily. This is similar to what happens when you get a mosquito bite—the area swells because inflammatory processes make tiny blood vessels leak fluid into the surrounding tissue.^[1]

If left untreated, chronic macular oedema can cause permanent damage. Prolonged swelling can lead to changes in the structure of the macula, including the death of photoreceptor cells and scarring. This is why early detection and treatment are so crucial—addressing the swelling before it causes irreversible damage gives you the best chance of preserving your vision.^[1]