What is diplopia?
Diplopia is a vision alteration consisting in the perception of double vision. This vision disturbance can be horizontal, vertical or oblique depending on how the images appear (to the side, above or diagonal to the object). In addition, it can affect both eyes (binocular) or only one eye (monocular).
Double vision can have different types and can be produced by several causes, some of them more serious than others. Strabismus, uncorrected refractive problems, cataracts, retinal diseases or some muscular and neurological alterations are some of the causes that can lead to double vision. Therefore, when the first symptoms appear, it is necessary to go for an urgent check-up.
Diplopia can be classified into:
- Monocular diplopia: Double vision is perceived with only one eye open.
- Binocular diplopia: Double vision occurs with both eyes open and disappears when either eye is closed.
Causes of diploplia are classified depending on the type of double vision.
Monocular double vision: In this case it is usually caused by eye structural causes, and in very few cases it is related to neurological alterations. Some of its causes may be:
- Eye alterations, such as refractive errors, which means that the patient requires glasses but does not wear any type of correction means, in which case it could be corrected by wearing glasses.
- Problems in the crystalline lens, such as cataracts, which may lead to experiencing double vision in that eye.
- Corneal diseases such as scars or opacities in the cornea.
- Retinal alterations, such as epiretinal membranes, which are membranes growing on the retina.
In all these eye structure alteration cases, once the alteration is corrected, double vision disappears.
Binocular double vision: In case of binocular double vision, a neurological alteration or eye muscle problems may be at the root of the problem. Some of its causes may be:
- An strabismus, which could be decompensated, that is, an eye deviation present from childhood that may be decompensated in adult age.
- Neurological alterations, such as paresis or intra-cranial nerve palsy (nerves that bring information to muscles and may suffer infarctions, which paralyses the muscles and causes an eye misalignment leading to double vision);
- Alterations in central nervous system, that cause an eye misalignment and, thus, double vision.
- Problems in neuromuscular junction, that is the union between the nerve and the muscle, such as myasthenia gravis.
- Other factors, such as thyroid problems or even mechanical problems in the extraocular muscles may also lead to eye misalignment.
Double vision or diplopia may occur at any point in life. Children may suffer from diseases leading to double vision, and, in case of strabismus, when the disease is being consolidated, during acute moments when there is a rapid decompensation, episodes of double vision may occur. Nevertheless, eye deviations caused by strabismus, especially in young ages, are usually compensated by our brain over time, and double vision is not consolidated. In case there has been a deviation from childhood, when the child reaches the adult age, he usually won’t experience.
Diplopia is a symptom reported by the patient, which is usually quite striking and causes a lot of visual discomfort, so the patient comes to the consultation saying that they “see double”.
In consultation, in order to carry out a diagnosis and determine why does the patient see double, we perform a comprehensive eye exam, including:
- An assessment of eye motility (ability of the eyes to move in coordination) in order to exactly determine whether there is a muscle that is not working properly due to a palsy or due to an hyperfunction of such muscle, which means the muscle is working more than it should;
- We perform orthoptics testing, which are measurements made in every sight position;
- We request additional tests going from general testing, hormone tests (in order to examine the thyroid) or even tests to rule out infectious or autoimmune diseases. Imagin tests could also be necessary and eye MRI or computerized tomography when a neurological or compressive cause is suspected, as well as electromyography when a muscle disease is suspected, among other tests.
Is it serious? Do I need to go to an emergency room?
A patient should go immediately to an emergency room in order to determine the cause.
If it is due to a decompensated strabismus, there will be enough time to perform an examination. However, it is important to rule out any neurological cause requiring urgent performing of studies and even hospital admissions in order to determine the cause of such double vision. Therefore, it is always recommended in case of acute double vision to go immediately an eye emergency room.
Treatment will depend on the cause of the diplopia. In case of monocular diplopia, which produces structural alterations of the eye, if these alterations can be corrected we will be able to solve the problem of double vision. However, in the case of binocular diplopia, if it persists, there are three therapeutic options:
- Prisms are lenses that are applied in glasses and help displace and, thus, correct the images causing double vision.
- Botulinum toxin: it is useful in some cases, when the patient does not adapt to prisms, or in certain cases of oculomotor paralysis.
- Surgery: Surgical intervention is usually only used to correct diplopia or double vision when the pathology or diplopia itself cannot be treated with prismatic correction.
Surgery that is carried out in case of eye misalignment is the same surgery performed in case of strabismus It consists of adjusting the muscles in order to correctly align the eyes. It is an outpatient surgery which usually does not require the patient’s admission. In most cases, the patient goes back home the same day of surgery. Procedure is performed under topical anesthesia effects with some kind of sedation. In some very specific cases, it may be performed under the effects of general anesthesia.
After a strabismus surgery, the recovery time is relatively short. Usually, patients may resume their daily tasks (job, studies…) within the first week after the surgery, depending on the complexity of the case. It is, however, recommended for patients to avoid going to the beach or swimming pool, as well as to not perform any sports contact during approximately the first 10 to 20 days.
During the postoperative period there may be some discomfort, such as a foreign body sensation or something rubbing inside the eye, but the evolution is usually favorable and in a few weeks it disappears completely.
The patient will need to follow a treatment with eye drops during the first month and to attend the required control visits.Usually, a control visit is scheduled 24 hours after surgery. Then, contingent upon the evolution, we carry out another control visit after a week. Finally, one month after surgery we are already able to determine the more or less definite surgery outcome and the impact it’s had on double vision.