Sudden double vision in a teenager: how to deal with it and how serious is it?

My son is 16 years old, suffers from headaches occasionally and has never worn eyeglasses. Last morning he woke up saying he was seeing double. Is it a worrying condition?

He replies Andrea Lemboophthalmologist, San Giuseppe Multimedica Hospital, Milan (GO TO THE FORUM)

There diplopia, or double visionis a visual symptom that manifests itself with the simultaneous perception of two images relating to the same object. It can be transient (and therefore disappear on its own), constant or intermittent (appears and disappears periodically). The ophthalmologist is one of the first professionals consulted to understand the causes, which can be very varied. First of all it is important to ask ourselves if it is a binocular or monocular diplopia, which means that it does not disappear by closing one eye. In the latter case, the phenomenon can be attributable to an uncorrected refractive error, such as astigmatism, or to a scar or other irregularity on the corneaor even the onset of cataracts or a retinal pathology.

Dry eye

Even in the dry eye syndrome double images can be created: in this case it is a diplopia that improves or attenuates by blinking and distributing the tear on the surface of the cornea. However, if double vision occurs with both eyes open and disappears when one eye is closed, it should always be investigated promptly, especially if the genesis is sudden. The professional who can support the ophthalmologist in this case is the orthoptist: by studying ocular motility, it is possible to understand whether diplopia is at the basis an unrecognized strabismus, therefore a failure to align the two eyes in one or more gaze positions which leads to the images not overlapping. For this to happen, a single binocular vision must first have been established.

Congenital strabismus

In fact it seems obvious but it is not: in conditions of sensorial normality, our brain receives an image from each eye, and the two images are merged into a single one through a sensory processing process. When this mechanism is disrupted, double vision occurs. That's what happens in some forms of congenital strabismus who have been well compensated up to that point and who suddenly decompensate in adulthood. Mechanical interference with normal eye movement may be related to a problem in neuromuscular transmission or a disease that affects the cranial nerves that innervate the eye muscles (as occurs in paralysis of the 3rd, 4th or 6th cranial nerve).

Neurological examination

Finally, it must be remembered that sudden onset diplopia is a phenomenon that must always be investigated, as it could hide a more serious clinical condition. If there is no clear monocular cause, the neurologist is the third fundamental figure in the diagnostic team. Neurological diplopia often requires further investigation with neuroimaging, i.e. with a CT scan or MRI of the brain. In summary, double vision can be caused by numerous conditions. Some causes of diplopia are relatively benign, while others require urgent medical attention. If a person reports seeing double, this must never be overlooked: the cause must be sought as soon as possible, whether it is an intraocular problem linked to motility or a neurological disease below.