Double vision (diplopia) – causes, treatment and prevention

Double vision (diplopia) causes the affected person to see an object twice: the two perceived images are then either next to each other or pushed over one another, sometimes at an angle or slightly rotated.

In this context, the perception of two adjacent images is referred to as horizontal diplopia. In contrast, seeing interlaced images is appropriately referred to as vertical diplopia.

causes

Double vision can be traced back to two mechanisms, each of which has different causes. In order to take a closer look at this, it is first important to distinguish between the two types of diplopia: binocular diplopia and monocular diplopia.In binocular diplopia, a point is projected onto different parts of the retina of the two eyes, which is also known as disparity. Binocular diplopia occurs, for example, in the context of disturbances in the balance of the eye muscles or paralysis of convergence, which means that the eyes are no longer moved parallel to one another or synchronously.

In addition, binocular diplopia can also be a consequence of squinting (strabismus) and can appear as both crossed diplopia (heteronymous or temporal diplopia) and uncrossed diplopia (homonymous diplopia or diplopia simplex). The latter falls under the term strabismus convergens (internal squinting: the eye is twisted towards the center of the face) when the double image appears on the side of the squinting eye; in the opposite case, when the double image is projected onto the retina of the non-squinting eye, the term strabismus divergens applies (outside squinting: the eye is twisted towards the edge of the face).

In the second form of double vision, monocular diplopia, a pixel is projected onto two different parts of the retina of one eye. Various causative diseases can be considered for this manifestation. One possibility is that the lens of the eye has become sclerosed (hardened), creating a double focus – which in turn causes the same image to be projected onto the retina twice (in different places).

Diplopia also occurs in irregular astigmatism, an irregular curvature of the cornea. Other causes may be diplocoria, which is congenital hole formation in the iris, or iridodialysis, which is tearing of the iris by blunt trauma to the eyeball.

Diseases

• astigmatism

• Squinting (strabismus)

• balance disorders

When to the doctor?

Anyone suffering from double vision should definitely be examined by a doctor. The reasons can be both harmless and very serious. For example, diplopia can hide a problem with the eyes that can be treated quickly and easily.

The first thing to do here is to contact the ophthalmologist, who will check whether there is any squinting or another eye disease. Triggers can also be migraines or circulatory disorders. If the ophthalmologist decides that the cause is not the eyes, then he or she will refer you to another specialist for further examinations.

The situation is more drastic when there are severe headaches and a sore left arm. These can be signs of a stroke. In this case, the emergency doctor must be contacted immediately. Since it is not immediately apparent which disease is causing the diplopia, a doctor should be consulted shortly after the symptoms first appear.

diagnosis and course

Since diplopia can have various causes, an exact diagnosis is usually made by means of several ophthalmological tests. While damage to the iris (e.g. in the case of iridodialysis) is easy to identify from the outside, the specific triggers for the different types of strabismus are less obvious.

The causes of internal squinting, for example, are not well known. In the case of paralytic squinting, one of the three relevant nerve pathways can be damaged so that convergent eye movements are no longer possible because the coordination between the two eyes is disturbed.

This can be examined by neuropsychological tests and imaging methods ( e.g. CT or MRI ). Astigmatism, such as irregular astigmatism, and even slight misalignments of the eyeballs can be detected and measured by an ophthalmologist using optical measuring devices.

complications

The complications of double vision that arise are highly dependent on the underlying cause. If self-controlled by squinting triggers, no further ailments occur. The frequency of double vision can be regulated, as well as the intensity or the end of squinting. Once the eye has been identified and squinting causes permanent double vision, the ophthalmologist can correct the squinting eye. Normal vision is restored and no further complications are to be expected.

However, if double vision does not occur in connection with squinting, serious illnesses can be the trigger. These are associated with individual side effects of varying duration and intensity. As soon as there is a lesion in the brain, it must be checked whether other areas of the brain are affected or whether there is a risk of the damage spreading. Disorders in the brain that are associated with tissue destruction often result in permanent impairment.

If the double vision is based on the presence of a tumor in the brain , this usually has to be surgically removed. The surgery comes with common risks and side effects. In addition, only after the procedure can it be determined whether the removal of the tumor also eliminates the symptoms it causes, such as double vision.

treatment and therapy

Once the cause of double vision (diplopia) is identified, it can be treated in many cases. If the reason for double vision is internal squinting, wearing glasses that correct the visual impairment can be sufficient, especially for children: Because many children squint slightly to compensate for short-sightedness .

With the help of appropriately ground lenses, a straight eye position can also be aimed at, which minimizes the angle of squinting. If this is not sufficient, an operation can be carried out in which the position of the eyes is surgically adjusted. In the case of early interventions in particular, the chances of recovery are very good.

For other causes of diplopia, such as irregular astigmatism, wearing specially ground lenses can also be enough to enable clear and simple vision. In the case of other eye diseases, especially after trauma, normal vision can only be restored by surgery. Alternative healing methods have not yet proven to be effective.

outlook and prognosisDiplopia can be caused by various diseases. The further course of this complaint depends very much on the underlying disease, so that a general prediction of the course is not possible in most cases. However, diplopia only very rarely disappears on its own, so that those affected are usually dependent on treatment for this complaint in order for the disease to progress positively.

If the diplopia occurs due to an infection , it is treated with antibiotics and other medications. In most cases, the course of the disease is positive and the symptoms are completely limited. If the diplopia is produced by a tumor, no prediction can be made. This tumor may also reduce the life expectancy of those affected. This complaint does not heal itself. Patients are then dependent on various visual aids to limit the diplopia. In most cases, the diplopia cannot be completely cured, so that those affected will usually always have to rely on visual aids.

prevention

To prevent diplopia, the eye should be protected from mechanical pressure. In particular at workplaces where there is a possible risk to the eyes, it is essential to comply with the relevant protective regulations.In order to prevent squinting – in both children and adults – ametropia should be noticed and corrected in good time. If you have a known visual impairment, for example in the form of short-sightedness, you should wear the prescribed visual aids (glasses or contact lenses) as recommended instead of doing without them.