Macular Edema

What Is Macular Edema?

Macular edema is an accumulation of fluid in the retina in the macula area. The macula is the central part of the retina and contains the fovea. This is the area of sharpest vision and the exit point of the optic nerve.

In macular edema, fluid leaks from the small vessels of the retina and choroid and accumulates in the retina. Usually, the so-called blood-retinal barrier prevents fluid from passing through. However, inflammation and blood flow, or other causes increase this barrier's permeability. The reason for this can be various diseases.

What Are the Causes of Macular Edema?

A common cause of macular edema is diabetic retinopathy. Diabetic retinopathy is a disease of the retina in diabetics. In this disease, increased sugar concentrations in the blood damage the small vessels of the retina. Diabetic macular edema is a complication that can occur in addition. Fluid from leaking vessels accumulates it in the macula area, and fat is deposited. This causes the macula to swell.

Inflammation can also cause macular edema. Inflammatory macular edema can occur with uveitis (inflammation of the middle layer of the eye) or due to surgery or trauma to the eye. Several factors are involved in the development of edema, including inflammatory mediators and oxygen radicals that damage the blood-retinal barrier. In addition, protein-rich fluid leaks from the vessels into the layers of the retina, forming edema.

In the past, macular edema often occurred due to cataract surgery. Surgical techniques have improved in recent decades, making macular edema less common after cataract surgery. However, macular edema can also develop after retinal surgery.

Another reason for macular edema can be a venous occlusion of the central retinal vein or a branch of the vein. This condition occurs mainly in older people. The reason for the occlusion is probably sclerotic changes or circulatory disturbances of the vessels. Edema probably results from the leakage of fluid and lipids from the damaged veins.

Macular edema may also occur due to diseases if traction on the retina is involved. In epiretinal gliosis, a multilayer membrane forms between the retina and vitreous. The newly formed membrane can pull the retina and damage the blood-retinal barrier. Traction on the retina can also occur due to incomplete vitreous body detachment. Detachment of the vitreous body is a normal aging process. However, sometimes the vitreous remains attached to the retina in the macular region. This can cause a pull, called vitreomacular traction, on the retina.

Retinal edema may also occur in the congenital retinal disease retinitis pigmentosa.

What Are the Symptoms of Macular Edema?

A typical symptom of macular edema is decreased visual acuity. Sometimes patients also have distorted vision. Rarely, enlarged vision occurs. This is because the sensory cells are forced apart by the fluid. However, macular edema does not always cause symptoms. For example, vision may not be affected if the macular edema is located outside the fovea, which is located in the center of the macula.

What Are the Different Forms?

Different forms of macular edema can be distinguished. It can occur focally or diffusely. Focal macular edema forms in only one area of the macula. In diffuse macular edema, the entire macula is loosened and diffusely thickened. Diffuse macular edema is often seen in diabetic retinopathy. Inflammatory macular edema usually occurs in the form of cystoid macular edema. Here, fluid-filled cavities form in the macula.

The macula thickened in venous occlusion, and the cystoid altered with superficial hemorrhages. Often macular edema is also classified according to whether or not fovea is involved. This is an essential criterion for treatment. The presence of visual impairment is also important for treatment and prognosis.

How Is Macular Edema Treated?

The treatment of macular edema depends on the underlying disease, the type of edema, and the clinical symptoms.

There are several options for the treatment of diabetic macular edema. Foveal involvement and visual acuity are important in deciding whether treatment is necessary. Medications can be injected into the vitreous body for macular edema with foveal involvement and visual impairment. This treatment is called intravitreal drug administration (IVOM). Medications can be either VEGF inhibitors or steroids. The endogenous growth factor VEGF (vascular endothelial growth factor) stimulates new vessel formation, increases vessel permeability, and has pro-inflammatory properties. VEGF inhibitors such as Aflibercept, Ranibizumab, and Bevacizumab inhibit VEGF.

Treatment with VEGF inhibitors is often well effective but protracted. The drug must be injected once a month for a period of 6 months. After that, additional treatments may follow. Intravitreal injection with steroids is required much less frequently. Steroids are potent anti-inflammatories but have more side effects than VEGF inhibitors. They can cause an increase in intraocular pressure or lens opacification. If the visual function is good despite foveal involvement, the risk of vision worsening in the near term is low. Therefore, in this case, it is possible to wait and see. Macular edema without foveal involvement can also be treated with laser coagulation.

Inflammatory macular edema is usually treated with Acetazolamide first, sometimes with steroid injections or systemic corticosteroid therapy. Acetazolamide causes fluid to be cleared through the blood-retinal barrier. If that does not help, steroids or VEGF inhibitors can also be injected into the vitreous.

Epiretinal gliosis and vitreomacular traction are treated surgically by removing the vitreous body (vitrectomy). After the surgery, there is also often a regression of the edema.

What Are the Chances of Cure and Prognosis?

The prognosis and chances of recovery from macular edema depend on the underlying disease and the extent of the edema. Diabetic macular edema is one of the most common causes of blindness. However, the disease can often be successfully treated with intravitreal drug administration of VEGF inhibitors.

If therapy is started late, when vision is already more impaired, it is unlikely that the same visual acuity can be achieved as with early treatment. Macular edema after eye surgery has a good prognosis. It often responds well to therapy.

After cataract surgery, it regresses spontaneously in most cases. Even with inflammatory macular edema in uveitis, good vision can usually be preserved with therapy today. Macular edema due to vein occlusion, on the other hand, has a worse prognosis and can lead to retinal atrophy.

Which Doctors and Clinics Are Specialists in Macular Edema?

Every patient who needs a doctor wants the best medical care. Therefore, the patient is wondering where to find the best clinic. As this question cannot be answered objectively and a reliable doctor would never claim to be the best one, we can only rely on the doctor's experience.

We will help you find an expert for your condition. All doctors and clinics listed have been reviewed by us for their outstanding specialization in macular edema and are awaiting your inquiry or treatment request.

Source Reference:

• Deutsche Ophthalmologische Gesellschaft (DOG)1 · Retinologische Gesellschaft
• e.V., Berufsverband der Augenärzte Deutschlands e.V. (2020) 3. Stellungnahme der DOG, der RG
• und des BVA zur Therapie des diabetischen Makulaödems. Stand August 2019. Ophthalmologe 2020, 117:218–247
• Haritoglou C, Ketnt M, Wolf A (2015). Diabetische Makulopathie. Ophthalmologe 2015, 112:817-885
• Heiligenhaus A, Bertram B, Heinz C, Krause L, Pleyer U, Roider J, Sauer S, Thurau S. (2014) Stellungnahme der Deutschen Ophthalmologischen Gesellschaft, der Retinologischen Gesellschaft
• und des Berufsverbandes der Augenärzte Deutschlands zur intravitrealen Therapie des Makulaödems bei Uveitis. Stand: 02.07.2014. Ophthalmologe 2014, 111:740–748
• Kampik, Grehn (2008). Augenärztliche Differentialdiagnose. Georg Thieme Verlag KG
• Thurau SR (2005). Zystoides Makulaödem bei Uveitis. Ophthalmologe 2005,102:485-490