Strabismus
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.
What Causes Strabismus?
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.
Pseudostrabismus
Pseudostrabismus is the false appearance of misaligned eyes. When eyes are truly misaligned, the condition is referred to as strabismus. In strabismus, the eyes can drift inward, outward, upward or downward. An infant’s eyes may drift in or out at times, but this small variable alignment can be perfectly normal. When a child begins focusing on the environment, at about two or three months of age, the eyes should be straight most or all of the time.