Strabismus in adults can happen because of disease that affects your eye muscles (such as thyroid eye disease and myasthenia), disease that affects the nerves to your eye muscles (such as high blood pressure and diabetes) or trauma (where a physical force is applied directly to your eye).
Strabismus can also be caused by trying to correct short- or long-sightedness, or by poor vision in one eye as a result of amblyopia (or ‘lazy eye’).
Strabismus may not cause any symptoms. For some people it can be serious.