Macular Edema

Generality

Macular edema is an affection of the eye, which occurs following a leakage of fluid from the blood vessels of the macula, or the central area of the retina.

With the leakage of this liquid, the macula itself swells and / or thickens, favoring the appearance of sight problems.

Thanks to an accurate and timely diagnosis, it is possible to solve the problem with more than fair results. Possible treatments include focal laser, corticosteroids, anti-angiogens and vitrectomy.

Short review of the anatomy of the eye

In the eye (or eyeball ), located in the orbital cavity, three concentric portions can be recognized, which from the outside towards the inside are:

The external habit (or fibrous frock). Area in which sclera (posteriorly) and cornea reside (anteriorly), acts as an attack for the so-called extrinsic muscles of the eyeball.
It has a fibrous nature.
The medium tunic (or uvea ). It is a membrane of connective tissue, rich in blood vessels and pigment.
Interposed between sclera and retina, it deals with providing nourishment to the retina, or rather to the layers of retina with which it comes into contact.
Includes iris, ciliary body and choroid.
The internal habit . It consists of the retina; the latter is a transparent film consisting of ten layers of nerve cells (or neurons), including the so-called cones and rods. Cones and rods are deputies to the visual function. In light of this, the internal habit has a nervous function.

Figure : anatomy of the eyeball.

What is macular edema?

Macular edema is a morbid condition of the eye, characterized by swelling or thickening of the macula, or the central area of the retina.

The presence of a macula so altered leads to the onset of more or less important sight disorders.

WHAT IS MACULA?

The macula (or macula lutea ) looks like a yellow spot about 5.5 millimeters in diameter.

Located to the side of the emergence of the optic nerve, at a distance of about 2.5 centimeters, it represents the retinal area with the greatest visual acuity and the greatest ability to identify details. Furthermore, containing more cones than rods, it is particularly sensitive to light stimuli and color perception.

At least 4 regions can be recognized in the macula: two of these are particularly important and are identified with the names of fovea and foveola (NB: foveola is the center of the fovea).

As for the vascularization, the fovea has large blood vessels all around and arterioles, venules and capillaries inside it; foveola, on the other hand, is avascularized.

The yellow color that distinguishes the macula is due to the presence of two carotenoids: lutein and zeaxanthin .

Causes

The cause of macular edema is the leakage of fluid from the blood vessels that supply the macula and retina in general.

To determine this particular phenomenon can be various situations, including:

Diabetes . Especially if not treated properly, this metabolic disease can be responsible for several vision problems, which take the generic name of diabetic retinopathy.
In the specific case, the diabetic patient suffers from macular edema because the blood vessels of the retina are damaged, which causes the loss of fluids containing blood cells and plasma proteins. The outgoing liquid is also called exudate and the leakage process is called exudation.
Cataract surgery . One speaks of cataract when the crystalline lens undergoes partial or total opacification. The crystalline lens is the natural lens of the eye, which allows to correctly visualize an object, an image etc. From the strictly functional point of view, it has the task of focusing on the retina the light that exceeds the cornea.
Macular degeneration related to advanced age . As you can guess from the name, it is a morbid condition of the macula that affects above all the elderly. According to some statistics, one person over the age of 65 would suffer every 10 years.
Uveitis . It is an inflammatory process against the uvea; the uvea is the thin vascular habit of the eye, which is interposed between the external ocular tunic (the one comprising sclera and cornea) and the retina.
Retinal vein occlusion . It is the medical term that includes all those circumstances characterized by an obstruction of the blood circulation inside one or more retinal veins. The blockage of blood circulation determines the appearance of retinal hemorrhages, which, in addition to macular edema, can also give rise to ischemic areas.
Eruptive macular telangiectasia . In medicine, telangiectasias are dilations of small blood vessels (venules, arterioles, and capillaries). Macular telangiectasia is a condition of the eye that affects the vascular system of the macula. The blood vessels take on a dilated appearance, with a tendency to form small aneurysms (microaneurysms) and other dangerous alterations.
Some genetic diseases, such as retinoschisis or retinitis pigmentosa . These are very rare hereditary diseases, which alter the normal morphological appearance or the cellular composition of the retina (and of course also of the macula).
Side effects of some drugs .
Eye trauma of a certain magnitude .

CLASSIFICATION OF THE MACULAR EDEMA

There are at least two types of macular edema: the cystoid form and the diabetic form.

Cystoid macular edema is characterized by the presence of areas filled with liquid, which are very reminiscent of cysts (which is why it is also called cystoid).
Its appearance can occur following all the above conditions, namely: diabetes, retinal venous occlusion, uveitis, macular degeneration related to old age, trauma of the eye, uveitis, etc.
Diabetic macular edema is characterized by the leakage of fluid from the retino-macular capillaries, directly into the spaces adjacent to the latter.
It is typical of people with diabetes, whether they have a proliferating diabetic retinopathy or a non-proliferating diabetic retinopathy.

Symptoms and Complications

Generally painless, macular edema can cause various symptoms and signs, including:

Loss of sight.
Blurred vision.
Central wavy view. In the human being, the central vision is used for the perception of details and colors. It is distinguished from the peripheral vision which, instead, concerns the perception of white and black, the perception in poorly lit environments and the identification of objects located outside the direct line of vision.
If the peripheral vision refers to the peripheral areas of the retina, the central vision refers to the macula .
Color vision altered. You may have difficulty recognizing the colors exactly or they may appear washed out, faded.

Depending on the cause, macular edema can be either unilateral - that is, one eye only - or bilateral - that is to say on both eyes.

WHEN TO REFER TO THE DOCTOR?

In the presence of one or more of the aforementioned symptoms, it is advisable to contact your doctor or an eye disease expert (ophthalmologist) immediately to find out the exact origin of the problems in progress.

COMPLICATIONS

Failure to treat macular edema (for example due to a late diagnosis) can lead to the onset of large visual deficits or even blindness.

Furthermore, there is the possibility that an alteration of the endocular pressure ( glaucoma ) results from a state of macular edema.

Diagnosis

In general, to diagnose the presence of macular edema, ophthalmologists use:

An examination of the fundus
A computerized optical tomography (OCT)
A retinal fluorangiography

EXAMINATION OF THE EYE BACKGROUND

The examination of the ocular fundus is a diagnostic procedure that allows to view the internal structures of the eyeball, therefore also the retina and the macula.

It can provide various interesting indications, even if often, for a better final evaluation, it is necessary to resort to more specific examinations.

Although it requires the use of some eye drops to dilate the ocular pupil, it is not a particularly invasive test.

COMPUTERIZED OPTICAL TOMOGRAPHY (OCT)

Computerized optical tomography ( OCT ) is a reliable and non-invasive diagnostic test that provides very precise scans of cornea, retina, macula and optic nerve.

The total duration of 10-15 minutes, involves the use of a laser beam of non-harmful radiation and can be performed even without necessarily having to dilate the patient's pupil.

In the case of macular edema, the detector instrument clearly shows if the macula is swollen / thickened and if there is an abnormal accumulation of fluid.

RETINAL FLUORANGIOGRAPHY

Retinal fluorangiography ( retinal fluorescence angiography ) is a photographic diagnostic procedure that allows the identification and study of vascular diseases of the eye.

It is based on the use of a dye, fluorescein, which, after being injected into a vein, spreads in a circle.

Thus, the diffusion of fluorescein is followed by means of an instrument - the retinograph - capable of taking real photographs (or frames) of the blood flow inside the retinal vessels.

The test takes about 10 minutes and may be slightly annoying when the dye is given into a vein.

In the case of macular edema, the frames show which blood vessels "leak" and what is the extent of the loss.

Treatment

The treatments for the treatment of macular edema include:

The focal laser
The administration of anti-inflammatory drugs and specific medicines against abnormal blood vessel growth
Vitrectomy surgery
Remedies for associated conditions (diabetes, glaucoma etc.)

The choice of the most appropriate therapeutic method is up to the doctor and is based, in general, on the causes of macular edema.

FOCAL LASER

The focal laser is indicated for patients with diabetes -induced macular edema or retinal vein occlusions . It is particularly effective in reducing the swelling of the macula and stabilizing vision (thus preventing further loss of vision); only rarely can it even improve vision.

The focal laser instrument emits laser beams, which, once directed towards the damaged retino-macular vessels, are able to favor the sealing process of the latter.

As is logical, the leakage of liquid is interrupted with vessel sealing.

Focal laser treatment is usually performed in an ophthalmologist's surgery, requires local anesthesia and involves the use of eye drops for pupil dilation.

Warnings regarding the focal laser

During the focal laser procedure, the patient may experience slight discomfort and see flashes and lights in the eye.

Moreover, at the end of the treatment and for several hours to follow, he will have the pupil or dilated eyes: this obliges him to be taken back home by a relative or a friend.

PHARMACOLOGICAL THERAPY

Drug therapy varies depending on whether the macular edema is diabetic or cystoid type.

In the case of diabetic macular edema, ophthalmologists generally resort to corticosteroid and anti-VEGF (or anti-angiogenic) injections.

In the case of cystoid macular edema, however, they prescribe eye drops (ie eye drops) based on NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) or based on corticosteroids.

Anti-VEGF . VEGF is the abbreviation for Vascular Endothelial Growth Factor, that is Vascular Endothelial Growth Factor . VEGF stimulates the formation of new blood vessels; in other words, it favors the process of angiogenesis. The anti-VEGF or anti-angiogenic drugs directly block VEGF or the effects it causes, thus preventing the development of other abnormal blood vessels starting from those already present.
Thanks to the anti-VEGF it is possible to reduce the leakage of liquid, slow down the loss of vision and improve visual skills. Among the anti-VEGF used are alfibercept (Eylea ®), ranibizumab (Lucentis ®) and pegaptanib sodium (Macugen ®).
Anti-angiogenic injections are performed using a special needle, which is inserted into the eye, near the retina. Since they are moderately delicate procedures, an ophthalmologist should take care of it, in his own clinic.
Everything happens under local anesthesia.
Corticosteroids are very powerful and effective anti-inflammatories (ie agents that reduce inflammation). However, a high and / or prolonged dose may cause side effects, sometimes even very serious.
The administration of corticosteroids in eye drops is a fairly simple treatment. In fact, it generally takes place from home and the patient himself can do it.
The administration of corticosteroids to be injected takes place in the same way as anti-VEGF. There is also the possibility of applying corticosteroids by means of implants (small cylinders "injected into the eye" which gradually release the drug over a few months); see the Ozurdex ® data sheet in this regard
Corticosteroids are used to reduce swelling and improve vision.
NSAIDs are fairly effective anti-inflammatories.
Especially since they produce modest side effects, they are prescribed before corticosteroids and are replaced by the latter only if they do not provide the desired results.
They are administered with the intent to reduce swelling and improve symptoms.

Please note. If cystoid macular edema is unresponsive to either NSAIDs or eye drops corticosteroids, the treating physician is forced to resort to corticosteroid-based injections.

VITRECTOMY

Vitrectomy is the surgical procedure of total or partial removal of the vitreous body, carried out in order to fix a vision disorder.

In the case of macular edema, after the removal of the vitreous humor, the ophthalmologist works to "eliminate" the liquid leaked from the vessels and to "repair" the damage to the vascular system.

To know in detail what the whole vitrectomy procedure involves, it is advisable to consult the article on this page.

Vitrectomy in its highlights:

Duration from 1 to 3 hours.
It can be performed under general or local anesthesia.
After the operation, scrupulously follow the doctor's instructions, in particular those concerning the insertion of the gas or oil bubble.
Eye drops are expected to prevent infections from arising.
Main complications: cataract and retinal detachment.