Typically, the eyes work as a team, aiming at the same spot, providing the brain with the information it needs to create a three dimensional image. This three dimensional image provides a person with depth perception. Strabismus also known as heterotropia, is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely affect depth perception.
The word strabismus most often brings to mind crossed eyes (esotropia), it also means any misalignment and includes walleyes (outward turning or exotropia) and one eye turning up or down (hypertropia or hypotropia).
Signs and symptoms
One eye moves normally, while the other points in out, up or down.
In fact, amblyopia refers to the brain’s ignoring input from one eye, which itself can result from discordance in the images provided by the eyes such as occurs in constant unilateral strabismus. It is also referred to as “crossed eyes”, “wandering eyes”, or having a “cast”. Other names include “squint”, “crossed eye”, “google eye”, “boss eye”, “cock eye”, “wonk eye”, “codeye”, “derpy eye”, “waz eye” and “wok eye”.
“Cross-eyed” means that when a person with strabismus looks at an object, one eye fixes on the object and the other fixes with a convergence angle less than zero; the optic axes overconverge. “Wall-eyed” means that when a person with strabismus looks at an object, one eye fixes on the object and the other fixes with a convergence angle greater than zero; that is, the optic axes diverge from parallel
Strabismus in Children
There are 2 most common types of strabismus in children: Accommodative esotropia – the eyes cross due to excessive farsightedness, and infantile esotropia, where children are born with the tendency to cross their eyes. Strabismus in children is less commonly caused by head trauma and diseases that affect the brain or nerves that go to the eye, such as tumors, hydrocephalus (water on the brain), or cerebral paralysis. In any childhood strabismus, amblyopia may occur. Often called “lazy eye”, amblyopia is when the brain shuts off the image in one eye long enough that the vision is permanently degraded in that eye. In most cases, this condition is easily resolved by simply patching the stronger, more developed eye and forcing the weaker eye to develop better sight.
Strabismus in Adults
In adults, new strabismus usually causes double vision. Head trauma and diseases which affect the nerves, such as multiple sclerosis, may cause it. Long-standing high blood pressure or diabetes can cause paralysis of eye movement muscles, as can an aneurysm in blood vessels supplying the brain or a tumor.
Treatment of Strabismus
Different forms of strabismus must be treatment differently:
Wearing glasses is possibility to correct farsightedness and allow the eyes to focus correctly. Accommodative esotropia is generally treated in this manner. Infantile esotropia, on the other hand, is usually caused by problems within the muscles that move the eye. These muscles must be operated upon to align the eyes. Often times, in cases of infantile esotropia when amblyopia (lazy eye) is also involved, the child must first wear a patch over their healthy eye in order to force the weaker eye to develop its vision. Once the amblyopia is solved, surgery can be performed to straighten the eyes. Other treatments for strabismus include eye exercises and injection of a drug called Botox into the eye muscles. An injection of Botox into an eye muscle temporarily relaxes the muscle, allowing the opposite muscle to tighten and straighten the eye. Although the effects of the drug wear off after several weeks, the misalignment may be permanently corrected in some cases.
How is Strabismus Surgery Done?
The ophthalmologist makes a small incision in the tissue covering the eye to reach the eye muscles. Certain muscles are repositioned during the surgery. People are usually able to resume their normal activities within a few days. After surgery, glasses or prisms may be useful. In many cases, further surgery may be needed at a later stage to keep the eyes straight.
Risks include infection, bleeding, excessive scarring, and other rare complications that can lead to loss of vision. Strabismus surgery is usually a safe and effective treatment for eye misalignment. It is not, however, a substitute for glasses or amblyopia therapy.
Early Detection is Key
Early diagnosis and treatment by a trained physician offers the best chance of getting the eyes working together.