Hypertropia

Causes

Hypertropia may be congenital or acquired, resulting from an imbalance in extraocular muscle function involving the superior rectus, inferior rectus, superior oblique, and inferior oblique muscles. These muscles can be paretic, restrictive due to fibrosis, or overactive. Congenital cases may involve developmental abnormalities such as muscle atrophy, hypertrophy, or rarely absence or incorrect placement of a muscle. Specific causes include superior oblique palsy (fourth nerve palsy), inferior oblique overaction, Brown's syndrome, Duane's retraction syndrome, double elevator palsy, fibrosis of the rectus muscle in Graves disease (most commonly the inferior rectus), and surgical trauma to vertical muscles during procedures like scleral buckling or cataract surgery.

Sudden onset hypertropia in middle-aged or elderly adults may result from trochlear nerve compression by a tumor, requiring urgent brain MRI, or from infarction of blood vessels supplying the nerve due to diabetes and atherosclerosis. It may also arise from abnormal neuromuscular transmission, as in Myasthenia Gravis.

Treatment

Treatment options for hypertropia include correction of refractive errors with glasses, prism therapy if tolerated for diplopia, vision therapy, patching for amblyopia in children or diplopia in adults, botulinum toxin injection, and surgical correction. Surgery aims to achieve binocularity, manage diplopia, or correct cosmetic defects, and the specific procedure depends on the mechanism and identification of offending muscles. A detailed orthoptic examination of ocular motility and visual status is required, and specialty fellowship trained pediatric ophthalmologists and strabismus surgeons are best suited for these complex procedures.