When a patient comes to our office and asks us, distressed, ".Why do I see double?"In the case of ophthalmologists, we are faced with the dilemma of assessing whether or not the patient suffers from a neurological disorder.
The patient is looking for a simple answer to his problem, "I see double", but listing the list of possible causes without going into further details, even in a simple way, is not usually the most reassuring for most patients.
What is diplopia or double vision?
We call double vision any visual disturbance that manifests itself as double vision, whether or not it affects the entire visual field, whether it follows lines, e.g. horizontal lines, or whether it occurs in one or both eyes.
Therefore, when we are asked about double vision and what it may be, we must respond calmly, conveying the need for a thorough review until we find the problem and solve it if it exists.
Types of double vision
The three most common types of double vision are as follows:
Double monocular vision
It affects only one eye and usually indicates a structural problem in the eye, and rarely corresponds to a neurological disorder.
Double vision is only perceived with the affected eye open, so it may be the patient himself who tells us, as soon as he sees us, that "with one eye I can see double".
Double binocular vision
It affects both eyes and disappears when either eye is closed.
Physiological double vision
In this case, what we see double are objects out of focus in the background of the visual field. If we add to this the fact that the brain learns to compensate for this visual alteration quite well, we could detect this type of diplopia in an examination motivated by another independent symptomatology. There are times when patients do comment that "I see double and blurred.".
Is it serious? When to see a professional
The double vision tells us that there is a problem and we need to find it in order to offer treatment. Diagnosis is not always straightforward, as we must look for problems in the structure of the eye to see if it is a neurological problem or a muscular disease. Each assessment usually requires a specialised diagnostic test.
Given the seriousness of some of the possible diagnoses, we recommend that you visit your ophthalmologist or, failing that, the emergency department when symptoms begin, as long as you do not have a previous diagnosis. The typical example: some migraines. Also go if the pattern of these episodes of diplopia changes at any time, or if they recur after treatment.
Treatment of diplopia
The treatment of double vision depends on where the cause of the double vision lies and may not be the responsibility of the ophthalmologist or may require joint work between different medical specialties.
- If the cause of double vision is damage to one or both optic nerves, the patient may have diabetes or multiple sclerosis. Tumours cannot be ruled out, although they are less frequent. It is necessary to work closely with other medical specialists who are also treating the patient.
- When the cause of double vision is located in the brain, we are faced with diagnoses as diverse as cerebral hypertension, aneurysms or tumours, without ruling out some migraines. In these cases, it is usual to refer the patient to another specialist, the neurologist or neurosurgeon, or to work together.
- If the cause of the double vision is a structural problem with the eye, then it is up to the ophthalmologist to treat it with vision therapy, corrective prisms or, if that does not work, surgery.
- When double vision is caused by muscular problems, we may be dealing with a case of strabismus or a muscle weakened by a neurological problem. Treatment may consist of the use of spectacles or contact lenses to improve vision or, depending on the case, surgery.
Blurred vision or double vision may be a sign of something serious. When faced with a distressed patient who says, "Doctor, I can see double," it is advisable to adopt a serious but not dramatic tone, and to explain a little so that the patient can understand what diagnostic tests we are going to perform and what we are checking with each one of them.