What is macular edema?

Macular edema is a pathology that occurs in the eye. Specifically, in the macula, a specific area of ​​the retina. It is a fairly frequent problem whose incidence has increased in recent years, since it is one of the secondary problems of diabetes.

However, macular edema is not always caused by this disease. On the contrary, its causes are multiple. The problem is that it can seriously affect vision. Above all, to the central vision and to the details. Do you want to discover what it is and how it is treated?

What is macular edema?

Macular edema occurs when more fluid than normal leaks through your blood vessels.

Before explaining what macular edema is, it is important to know the retina and the macula. The retina is the light-sensitive tissue of the eye which is located at the back of the eyeball.

Its function is to receive light rays and transmit the information in the form of electrical impulses that travel through the optic nerve to the brain. In this way, the retina allows the vision process to take place. The macula is a specific part of the retina which is responsible for central vision and perceiving the detail of objects.

Numerous blood vessels run near the retina. When a person suffers from macular edema, more fluid leaks through these blood vessels than normal. This fluid collects around the macula, causing it to swell and distort vision.

Fluid build-up can occur when blood vessels are more permeable than usual or their walls are thinner. As the specialists of Institut de la Màcula, macular edema is often associated with diabetes. However, as already noted, not all cases of macular edema are due to this disease.

Whatever the cause of macular edeme, the presence of this disease impairs vision; specifically, central vision is impaired and peripheral vision, as a rule, is maintained.

Causes of macular edema

Although macular edema occurs because fluid accumulates abnormally near the macula, the causative processes can be very varied. We explain what they are.

Diabetic macular edema (DME)

Macular edema is one of the most common diabetic eye problems. It is an event that usually accompanies diabetic retinopathy, a process that takes place by a continuous damage of the blood vessels.

This damage occurs because the concentration of glucose in the blood remains above normal over time. Therefore, it is more common in people who have poor diabetes control.

According to data from National Eye Institute, diabetic retinopathy is considered one of the leading causes of blindness and macular edema is usually one of its signs.

On the other hand, a study published in Annals d'Oftalmologia points out that the incidence of diabetic macular edema is not well known. However, its prevalence is estimated to be between 7.5 and 15% of all type 2 diabetics.

The truth is that edema can appear in any phase of retinopathy. However, it is more frequent as the damage progresses. Certain factors also influence its development, such as blood pressure or blood sugar levels.

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Eye surgery

Macular edema can also be the result of surgery performed on the eye. The experts of American Academy of Opthalmology explain that may be secondary to surgery to treat cataracts or glaucoma. However, it is not very common. In addition, in these cases it is usually a mild and easy to treat edema.

One of the consequences of cataract surgeries can be the appearance of macular edema.

Macular degeneration associated with age

This pathology, as its name suggests, is a degenerative process that affects the macula. It is common in aging, since the ocular tissues, like the rest of the body, are susceptible to the passage of time.

What happens is that, in a specific type of macular degeneration called 'wet degeneration', new and more fragile blood vessels begin to proliferate towards the retina. Thus, it is possible that the fluid escapes more easily and accumulates around the macula, causing edema.

Blockage of blood vessels in the retina.

Another cause of macular edema is the obstruction of the blood vessels that drain the retina. Specific, it is more frequently due to an occlusion of the venous branch of the retina.

This vein can become clogged due to numerous problems. For example, due to atherosclerosis, high blood pressure or, also, due to diabetes. When this happens, the fluid begins to leak and also accumulates on the macula.

Other causes of macular edema

This pathology can be the consequence of many other eye diseases. For example, may be due to an inflammatory process, such as uveitis. This pathology consists of inflammation of the uvea, the middle layer between the retina and the sclera of the eye. In this layer, many blood vessels are found.

According to the University of Navarra Clinic, uveitis can appear, in turn, in many systemic disorders. Some of them are Behcet's disease, psoriasis, Kawasaki disease, arthritis, etc.

What symptoms does it produce?

Macular edema it usually affects central vision. That is, vision becomes blurry when trying to focus on an object that is in the center of the field of vision.

Further, colors can also be affected. It is common for people with macular edema to see slightly discolored colors. It is also common to have difficulty reading.

However, symptoms may not appear until fluid build-up is quite advanced. On the other hand, vision in peripheral fields is usually preserved. That is, you can see something placed to the side, but not something placed in front of that person.

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How is it diagnosed?

The diagnosis of macular edema requires that the ophthalmologist perform a series of tests to check both possible eye injuries and the state of vision. Therefore, one of the most used tests is the fundus.

The fundus, also called ophthalmoscopy, is a test that allows you to see the retina and the macula. To do this, a pupillary dilation is usually performed first, which allows this area to be seen more clearly. Also, the integrity of the blood vessels is observed.

Another fundamental aspect is measuring visual acuity. By means of these tests, the decrease in the quality of central vision can be observed. In addition, they help to check whether peripheral vision is preserved or not.

There are other more specific tests that are used when there is a strong suspicion of macular edema. One of them is fluorescein angiography. As detailed by the Innova Ocular clinic, this test consists of injecting a contrast (fluorescein) and checking the ocular circulation.

Treatment of macular edema

Treatment of macular edema depends, first of all, on its cause. It is important to treat the underlying cause to prevent it from happening again. For example, in the case of diabetic macular edema, it is essential that these people understand why it has happened and follow strict blood glucose monitoring to prevent its occurrence.

For the edema itself, a number of treatments have been developed that focus on preventing extravasation of fluid through the blood vessels. One of the most used techniques is the injection of anti-VEGF.

VEGF is a vascular endothelial growth factor: that is, a stimulus for the retinal blood vessels to proliferate. This is a problem, as the new glasses are more fragile.

Therefore, by injecting anti-VEGF it is achieved that new vessels do not grow. In this way, the risk of fluid escaping and accumulating around the macula is reduced. Injections are required from time to time for the treatment to be effective.

Another treatment is corticosteroids. They are drugs that reduce inflammation. For this reason, they also improve the process that occurs at the macular level. They can be applied through drops or injections.

Remember: some causes of macular edema are preventable

It is important to emphasize again that macular edema is closely associated with diabetes, a pathology that can lead to blindness. Therefore, it is essential that People with diabetes go to the ophthalmologist and medical check-ups frequently.

Similarly, anyone who begins to notice alterations in vision should always consult a specialist. Especially if you have had any previous eye problems, such as glaucoma or cataracts.