The 5 most frequent doubts about retinal detachment

What is a retinal detachment?

The eye is made up of three main layers like “onion layers”. The first layer, if we look at it from the outside in, is formed by the cornea and the sclera.

The cornea is at the front of the eye and is a transparent dome through which we see the iris and pupil, known as the “apple of the eye”.

The sclera is the white part of the eye that we see, especially when we look sideways and is rigid and gives the eye strength.

The second layer is the choroid, which we cannot see because it is inside the sclera (the white layer). It is a layer with a large blood supply, since the eye needs a large blood supply to carry out its visual function.

The third layer, the innermost, inside the choroid, is the retina. It is composed of nerve tissue, which contains all the photoreceptor cells, i.e. those that collect the light and images that reach the inside of the eye, and the fibers that transmit these images to the brain through the optic nerve.

These three layers are superimposed on each other, as we said before, like the layers of an onion. A retinal detachment is the separation of the innermost layer that separates, or detaches from the choroid, losing its functional capacity and resulting, if not repaired, in a loss of vision that may be irreversible.

Why does it occur?

The eye is a more or less spherical structure. Its walls are composed of the three layers we have already mentioned, which leave a cavity in its interior. In the anterior part of this cavity we can find the iris and the crystalline lens, which is a transparent structure that acts as a lens. This lens allows us to focus both near and far, and when it becomes opaque over the years, we call it a cataract.

Most of the cavity that forms the eye, from behind the crystalline lens to the retina, is filled with a transparent gel that we call vitreous. The vitreous is very compact, homogeneous and transparent when we are young, it fills this internal cavity of the eye and is tightly bound to the retina. Over time, as we grow older, the vitreous begins to undergo evolutionary changes that cause it to liquefy more and more and transform into an increasingly liquid structure, which contains fibrillar structures floating inside it. These structures are often described by the patient as “floaters”.

While the vitreous remains a compact and homogeneous structure, it accompanies well the movements made by the eye when looking up, down or to the sides, but as it liquefies more and more, the vitreous begins to move inside the eye, like a wobble, every time the eye moves. At the same time that this liquefaction of the vitreous occurs, another phenomenon takes place, which is the progressive weakening of the junction of the part of the vitreous that is attached to the retina.

At a certain point, as the vitreous liquefaction becomes greater and greater and the bond with the retina becomes weaker and weaker, the vitreous becomes abruptly separated from the retina. This phenomenon is known as posterior vitreous detachment and, although most of the population is unaware of it, it is something that will happen to practically all people who reach advanced ages.

When the vitreous separates abruptly from the retina, it remains condensed inside the ocular cavity. Clinically the patient usually notices it, because the sensation of floating bodies inside the eye increases very noticeably and abruptly. People describe it as flies, threads, tangles, cobwebs, clouds… that move from one side of the vision to the other when moving the eye and that we know as myodesopsias. It also usually gives rise to another very characteristic symptom which is the appearance, usually on the side of the affected eye, of flashes, lightning, or other luminous phenomena of short duration that usually appear in moments of darkness or low ambient illumination, which we know as photopsias.

In most people the posterior vitreous separates completely from the retina without damaging it and the photopsias disappear gradually, without interfering with the patient’s normal life. But in a small number of people, when the vitreous separates from the retina, it can pull the retina, breaking it and giving rise to what we know as a retinal tear, that is to say, a break or hole in the retina. Through this hole, the vitreous, which is already very liquefied, can leak, occupying the posterior part of the retina, detaching it from the choroid and causing what is known as retinal detachment.

What are the symptoms?

They are usually preceded by the symptoms of posterior vitreous detachment that we have already mentioned: photopsias and midesopsias.

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In any case, the main symptom is the loss of vision, as the retinal area that detaches gradually loses its ability to see. This loss of vision occurs in a very characteristic way. The patient retains vision in the central part of the retina and begins to lose vision in the periphery. Either above, below, or on the sides, a black area begins to appear like a curtain, which does not move like myodesopsias, but always stays in the same place, it moves towards the center and where it advances it takes away the patient’s vision. If the detachment reaches the central area, vision is lost in a very important way.

How can it be prevented?

It is advisable to have regular fundus examinations, especially in myopic patients or those with a history of retinal detachment in the other eye or in the family. Sometimes we find in the peripheral retina more degenerated or weaker areas and, therefore, with more possibilities of rupture. In patients at risk it may be convenient to treat these lesions with laser as a preventive measure.

In any case in patients with symptoms of acute posterior vitreous detachment, it is absolutely essential that the fundus is checked to rule out retinal tears, because if we find a tear before a retinal detachment has occurred, it is easily treatable with laser and we would prevent the detachment from occurring.

It is important to emphasize the presence of “floaters”, which is frequent in myopic people, even young people. This can cause anxiety in them, because they think they pose a high risk to their vision, but it should not be confused with a posterior vitreous detachment. A vitreous detachment under the age of 50 is very rare, unless the patient suffers a traumatism, has a very high myopia or the eye has had a previous surgery or there are certain pathologies.

What are the treatment options?

When a retinal detachment is already established, the treatment must necessarily be surgical. There are basically three surgical possibilities.

  • Pneumatic retinopexy: few retinal detachments can be treated with this technique, since it requires that the detachment is in the upper part of the retina and has a single tear. It consists of injecting a bubble of a gas inside the eye, which is placed in the upper part, pushing the retina towards the ocular wall and gluing it. The tear must then be treated so that when the gas is reabsorbed, the retina remains attached. This treatment can be done with laser or with a cold probe (cryotherapy), which freezes the edges of the tear. During the time the gas is kept inside the eye, the patient must remain in an upright position, standing or sitting, without lying down.
  • Scleral surgery: it is the most classic technique to treat it. It consists of placing implants in the external wall of the eye. When the retina detaches from the wall of the eye, it moves inward. If we push the wall of the eye, from the outside inwards, we can get it to contact the retina again and the retina sticks to it again. This is achieved by placing isolated implants to push a certain area of the retina inward, usually to contact the retina at the site of the tear, or by placing a circular implant around the eye as a belt, which we call cerclage.
  • Posterior vitrectomy: the most current, which consists of entering the ocular cavity, removing most of the vitreous to suppress traction on the retina, gluing it, locating and lasering around the tears. The only slight inconvenience for the patient is that the laser produces small burns around the edges of the tear. The laser is effective when these burns heal, making a kind of weld around the tear and preventing fluid from re-entering it. But it usually takes two or three weeks from the time the laser is given until it heals properly. During this time something must be left inside the eye to hold the retina until the laser heals. That something is usually a gas or silicone oil. The disadvantage of the gas is that it prevents the patient from seeing well until it is reabsorbed, forcing the patient to rest a lot, usually face down. The advantage is that if it is reabsorbed on its own, if the retina remains attached, nothing more needs to be done. The silicone is transparent, so it allows the patient to see something, but in the long term it can be toxic for the eye and a second intervention is needed to remove it. Silicone is saved for the most difficult cases, second interventions or in patients who cannot rest.