What is Strabismus?
In patients with Strabismus, the two eyes do not line up together properly to look at the same object. In some people with strabismus the condition can be very obvious to any onlooker who will immediately notice that the eyes are clearly misaligned, crossed or turned outward or turned inward. strabismus is often called "crossed eyes" when the eyes are turned inward towards the nose or "wall eyes" when the eyes are turned out towards the wall. However, it is important to be aware that in some cases strabismus is only obvious to an eye doctor but still must be taken seriously and treated.
Alternative names for strabismus include, crossed eyes, esotropia, exotropia, hypotropia, hypertropia, squint, walleye, misalignment of the eyes, comitant strabismus, noncomitant strabismus.
What causes strabismus?
Six different muscles surround the eyes and allow them to move. Normally the eye muscles work as a team so that both eyes can focus on the same object. However, in patients with strabismus, the eye muscles do not work together and the eyes do not "team up" properly. The result is that one eye looks at one object while the other eye turns in a different direction and is focused on another object.
In most children with strabismus, the cause is not known. In more than half of these cases, the problem is present at or shortly after birth and is called congenital strabismus. Most of the time the misalignment of the eyes has to do with muscle control, and not with muscle strength. More rarely, problems with one of the nerves or muscles, or graves disease restriction may cause strabismus.
Other disorders associated with strabismus include:
- brain and nerve disorders, such as traumatic brain injury, stroke, cerebral palsy, or Guillain-Barre syndrome;
- diabetes (causes a condition known as acquired paralytic strabismus);
- damage to the retina in children who are born premature;
- hemangioma near the eye during infancy;
- injuries to the eye;
- tumor in the brain or eye; and
- vision loss from any eye disease or injury.
A family history of strabismus is a risk factor. Farsightedness may be a contributing factor, especially in children. Any other disease that causes vision loss may also cause strabismus.
Photo by Artem Beliaikin on Unsplash
How does strabismus effect the patient's vision?
When each of the two eyes is focused on a different object, two different images are sent to the brain - one from each eye. This is not normal and two different images cannot be simultaneously processed by the brain which is forced to ignore one of the images. Over time, the brain may learn to ignore the image from the weaker eye.
If the strabismus is not treated, the eye that the brain ignores will never see well, causing a condition called amblyopia in the ignored eye. Amblyopia is often called "lazy eye." The onset of the two conditions may also be reversed with the patient first having amblyopia, which then causes strabismus. Other vision problems associated with strabismus include stereopsis (the inability to see in three dimensions) and diplopia (double vision).
Strabismus, anxiety and depression
Sometimes eye health overlaps with mental health. A study from The British Journal of Ophthalmology identifies the psychological factors associated with strabismus. The study looked at the psychological and social well-being of 220 patients with strabismus and found that 11% of them experienced clinical depression and 24% experienced clinical anxiety.These numbers were mostly due to negatives beliefs about strabismus, even more so that clinical factors such as double vision.
The study highlights the need for doctors to pay attention to the psychological and social aspects of strabismus when treating patients, as these factors are significantly correlated to the patient's well-being.