Macular edema is condition that affects 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, as it is one of the secondary problems of diabetes.
However, this is not always the case. On the contrary, its causes are multiple. It can seriously affect vision, though. Above all, the central vision and the details.
Macular edema occurs when more fluids than normal leak through your blood vessels.
The retina is the light-sensitive tissue of the eye at the back of the eyeball.
It receives light rays and transmit the information in the form of electrical impulses that travel through the optic nerve to the brain. The retina, this way, allows the vision process to take place. The macula is a specific part of the retina that is responsible for central vision and perceiving the detail of objects.
Numerous blood vessels run near the retina. When suffering from this disease, a person has leakage of more fluid through these blood vessels than normal. Around the macula, the fluid accumulates, causing it to swell and distort vision.
Fluid accumulation can occur when blood vessels are more permeable than usual or their walls are thinner.
Whatever the cause of macular edema, 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 the pathology occurs because fluid accumulates abnormally near the macula, the causative processes can be very varied. We explain what they are.
Diabetic macular edema (DME)
This is one of the most common diabetic eye problems. It is an event that usually accompanies diabetic retinopathy, a process that occurs due to continuous damage to the blood vessels.
This happens the concentration of glucose in the blood remains above normal over time. So, it is only natural that it is more common in people who have poor diabetes control.
According to data from the National Eye Institute, diabetic retinopathy is considered one of the main causes of blindness and macular edema is usually one of its signs.
Its prevalence is estimated to be between 7.5% and 15% of all type 2 diabetics.
The reality is, the disease can appear in any phase of retinopathy. However, it is more frequent as the damage progresses. Certain factors also play a role in its development, such as blood pressure or blood sugar levels.
Eye surgery
An eye surgery can also cause the disease. Experts from the American Academy of Ophthalmology explain that it may be secondary to surgery to treat cataracts or glaucoma. However, it is not very common. In fact, these cases usually represent a mild and easy to treat type of the disease.
Macular degeneration associated with age
This disease is a degenerative process that affects the macula. It happens due to 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 into the retina. Chances are that fluid escapes more easily and accumulates around the macula, causing edema.
Blockage of the blood vessels in the retina
The obstruction of the blood vessels that drain the retina cause the disease. Specifically, it is more frequently due to an occlusion of the venous branch of the retina.
There can be clogging in the vein due to numerous problems. For example, by atherosclerosis, high blood pressure or, also, by diabetes. When this happens, the fluid begins to leak and also accumulates on the macula.
Other causes of macular edema
This pathology can be a consequence of many other eye diseases. For example, it may be due to an inflammatory process, such as uveitis. There’s an inflammation of the uvea, the middle layer between the sclera and the retina of the eye. In this layer, many blood vessels are found.
Uveitis can appear in many systemic disorders. Some of them are Behcet’s disease, psoriasis, Kawasaki disease, arthritis, and so on.
What symptoms does it produce?
Macular edema usually affects central vision. Vision becomes blurry when trying to focus on an object that is in the center of the field of vision.
Furthermore, colors can also be affected. It is common for people with the disease see slightly discolored colors. It is also common to have difficulty reading.
However, symptoms may not appear until fluid build-up is well advanced. On the other hand, the vision of the peripheral fields is usually preserved.
How to diagnose it?
The diagnosis 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 widely used tests is the fundus.
The test, ophthalmoscopy or fundus, is a test that allows you to see the retina and the macula. To do it, a pupillary dilation is usually performed first, which allows this area to be seen more clearly.
Another fundamental aspect is measuring visual acuity. Through these tests, the decrease in the quality of central vision can be observed.
And, then there’s the fluorescein angiography. Injecting fluorescein, a contrast, and checking the ocular circulation with it is how this test goes.
Treatment of macular edema
Treatment depends, first of all, on its cause. 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 control to prevent its appearance.
There is a number of treatments that focus on preventing extravasation of fluid through the blood vessels. The injection of anti-VEGF is one of the most popular techniques.
This is a vascular endothelial growth factor: that is, a stimulus for the retinal blood vessels to proliferate.
By getting the anti-VEGF, new vessels do not grow. It helps reducing the risk of fluid escaping and accumulating around the macula. For the treatment to be effective, injections are necessary.
Another treatment is corticosteroids. They are drugs that reduce inflammation. They can be applied through drops or injections.
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