Strabismus, also known as crossed eyes or wall eyes, is a condition in which the eyes are not aligned (they don't look towards an object together). One of the eyes may look in or out, or turn up or down. The eye turning away can occur all of the time or only sometimes, such as during stressful situations or illness.
Most of the focusing power in the eye occurs along the front surface, called the cornea, which is the clear "window" in the front of the eyeball. The next structure involved in focussing is the lens, which sits behind the cornea inside the eye. The ideal cornea has a symmetrically curved surface, like a basketball. Astigmatism is caused by a cornea or a lens that is not symmetrical. As a result, people with significant astigmatism may have distorted or blurry vision.
Astigmatism is measured in...
Some people are born with eyes that do not align in the usual way. This is called congenital strabismus. In many children, there is no clear cause of strabismus. In some cases, it is a result of a problem with the nervous system, especially the part that controls the muscles of the eyes. It may be due to a tumor or disorder in the infant eye. If it is not corrected, strabismus can continue into the adult years. Most adults who have strabismus were born with it.
If strabismus does not appear until later in life, it will cause double vision. If the eyes become misaligned in an adult who did not have strabismus as a child, it could be a sign of a serious condition such as a stroke. A sudden misalignment of the eyes, or double vision, are important reasons to see a doctor immediately.
Young children have the ability to suppress vision in a misaligned eye, thereby avoiding the symptom of double vision. However, that may lead to an eye becoming amblyopic or "lazy." Depth perception and peripheral vision (vision off to the side) may be affected. Eyestrain and headaches can occur. When misalignment of the eyes first occurs at an older age, a person may turn his or her head in unusual ways in order to see in certain directions and avoid double vision.
How Is Strabismus Treated?
If strabismus is suspected, a pediatric ophthalmologist should be consulted. Non-surgical treatment may be initially recommended, with the main goal to assure that neither eye becomes amblyopic (lazy) and if that tendency is present, to prescribe optimal eyeglasses and force the use of the lazy eye (with a patch or other measures) until normal vision is established. In some cases, the misalignment of the eyes is caused by excessive farsightedness and eyeglasses may solve the strabismus without eye muscle surgery. The main goal of vision therapy (including optical devices) is assuring that a lazy eye gets visually exercised before the child reaches the age of 8 or so and permanent visual loss occurs. Amblyopia (lazy eye) must be treated in childhood to avoid permanent visual loss.