Hypertropia

By convention, when one eye is positioned higher than the other, the higher eye is the one that is labeled as being out of alignment – this is called a hypertropia and the higher eye is “hypertropic” relative to the other eye.   This is the case even though the problem may actually be that the other eye is lower (hypotropia).  Again, the important point here is that the problem is the alignment of the eyes relative to each other. 

One of the most common causes of hypertropia is a problem with the eye muscle that rotates the eye down and in towards the nose (the superior oblique muscle).  When the eye cannot be fully rotated down and in towards the nose, the muscle that balances the superior oblique (called the inferior oblique) is unopposed and does it’s job exceedingly well.  The function of the inferior oblique is to rotate the eye up and out towards the ear.  Therefore, when the superior oblique is weak (paretic) or not working at all (palsied), the inferior oblique is unopposed and it twists the eye up and out – to avoid double vision, people with this problem will tilt their head to make up for the eye being rotated.

Superior oblique palsy often presents in early childhood with a head tilt.  When diagnosed in an infant, it is best to correct a superior oblique palsy before too much time has passed because a head turn before the age of 2 years is associated with permanent changes in the development of the face.  Also, the neck muscles and bones can be affected by the head tilt.  In older children and adults, most cases of superior oblique palsy have actually been present since childhood but have become more pronounced with time – these patients often complain of eyestrain or “headache” and may not realize that they are tilting their head.  In older adults, superior oblique palsy can be associated with atherosclerosis, diabetes, or high blood pressure – this type of strabismus often gets better on it’s own.    Regardless of the age, or the cause, superior oblique palsy can be managed very effectively when properly diagnosed.

Another common causes of hypertropia in adults is thyroid disease, which can affect the eye muscles (Graves’ ophthalmopathy).   Graves’ ophthalmopathy can occur in people whose thyroid gland is overactive (hyperthyroid), underactive (hypothyroid), or even normal (euthyroid).  Surgery is often needed to eliminate the double vision and abnormal head position.    

At other times, a hypertropia is due to a misalignment of the horizontal muscles of the eye; getting the eyes horizontally aligned will then correct the hypertropia. Other causes of hypertropia include stroke, head trauma, tumor, and certain inflammatory disorders.