Strabismus is the deviation of one of the eyes with respect to the other. This deviation can be outward (divergent strabismus), inward (convergent strabismus) or vertical. It may occur in all or only in certain positions of the gaze, near and/or far, and may be the consequence of the alteration of one or more muscles.
Gaze deviation may originate in childhood and persist into adulthood, or occur in adulthood. It is common to find patients who reach relatively advanced ages without treatment of their disease.
What are the causes of strabismus?
Strabismus in adulthood can be the result of trauma to the orbit that can trap the muscle in the fracture zone or be secondary to paralysis of muscles that rotate the eye, common in patients with cardiovascular risk factors (diabetes, arterial hypertension, etc.).
It is also common to find strabismus that originates in childhood and persists into adulthood. In this case the causes are the usual ones of childhood strabismus: from high myopia or hyperopia to alterations in the movement or strength of certain eye muscles, as well as neurological problems that have repercussions on ocular alignment.
What are the symptoms of strabismus?
It mainly manifests itself as an ocular deviation (which may or may not be evident to the naked eye, constant or intermittent, near or far and in some or all eye positions). It can also lead to loss of binocular vision and spatial perception. When strabismus appears suddenly (for example, if it is the result of muscle paralysis) it can cause double vision (diplopia).
If strabismus is present from childhood and is not corrected during the early years, it is often associated with a lazy eye. This occurs because the brain overrides the image of one of the eyes (usually the one that is more deviated or has worse vision) to avoid double vision.
Apart from parents being able to detect the deviation on a day-to-day basis, it is important to have regular ophthalmopediatric check-ups: before the age of 1 year if indicated by the pediatrician or if there is a history of serious eye disease in the family, and at 3 years of age as a general rule.
How is it diagnosed and treated?
By seeing a specialist, the cause of strabismus can be identified and treated. Tests are performed to determine visual acuity, spatial perception and measure ocular deviation.
Strabismus treatment aims to achieve correct alignment of both eyes. It consists of several stages:
- A proper prescription of the patient’s glasses.
- The treatment of the lazy eye if it exists, usually by means of patches (in childhood).
- The use of prisms, if the deviation is small and the patient manifests double vision (in adulthood).
- Corrective surgery, if the deviation persists after the previous steps.
Strabismus surgery acts on one or several eye muscles, weakening or strengthening them as needed. Depending on the type of strabismus, it may be necessary to act on one or both eyes of the patient.
Since visual capacity is not recovered after 10 years of age, the intention of this intervention is eminently cosmetic, since there is currently no technique that allows recovering the vision of the lazy eye if it has been produced as a consequence of strabismus.
Surgery in adulthood can be performed under general or regional anesthesia. In both cases the patient can return home the same day.
What advances have been made in the last decade in the treatment of this pathology?
The latest research in this field is aimed at treating lazy eye more effectively and earlier, by means of games on screens and even virtual reality techniques, although patching is still the treatment that offers the best results. There are also several studies that are trying to find a way to estimate the position and strength of the ocular muscles without having to take the patient to the operating room.
From a surgical standpoint, techniques are constantly being refined to achieve smaller incisions that allow for faster recoveries after surgery, as well as to treat less common types of strabismus.