Strabismus refers to an eye that deviates in, out, up or down.  It is often referred to as an eye turn.  There are six muscles in each eye that ideally keep the eyes pointed forward.  If there is an imbalance in these muscles, strabismus can result.  The tendency for the eye to drift may be intermittent (especially with fatigue) or constant.  It is most often present from birth, but can be later onset if secondary to trauma or a neurological deficit.  When strabismus occurs, you will either have double vision or your brain will learn to suppress or “turn off” the deviating eye.  If suppression occurs in early childhood, this can lead to amblyopia, which is a lazy eye that does not develop good vision from lack of use.  The more constant strabismus is, the more likely amblyopia will develop.  However, not all people with strabismus will go on to develop amblyopia.  Parents are often the first to notice strabismus, but the signs are not always obvious.  An eye examination will determine whether strabismus is causing amblyopia or not.  Strabismus treatment may vary from spectacle correction, prisms, surgery to realign the eye, vision therapy to help train the eye muscles, patching to treat any associated amblyopia, or even just monitoring the condition if it is mild.  Your eye care provider can tell you which of these options are best for you or your child.  The most common types of strabismus are esotropia (the eye turns inward, or crossed eyes) and exotropia (the eye turns outward).  Because strabismus can affect vision development in children, and because it can be a sign of a serious medical condition with sudden onset in an adult, it is important to have an eye examination as soon as possible if you have symptoms.