Hypertropia (Vertical Strabismus)

Hypertropia is a form of vertical strabismus where one eye is higher than the other in primary position. By convention, the deviating eye is named (e.g., right hypertropia means the right eye is higher). Causes include congenital superior oblique muscle palsy (most common cause of vertical diplopia in adults), acquired trochlear nerve palsy from microvascular ischemia or trauma, dissociated vertical deviation in children with congenital esotropia, third nerve palsy, thyroid orbitopathy, orbital floor fracture with inferior rectus entrapment, Brown syndrome (restricted superior oblique tendon), and skew deviation from posterior fossa lesions.

Symptoms include vertical diplopia (especially in adults with acquired hypertropia), abnormal compensatory head tilt to neutralize deviation (tilt away from affected eye in superior oblique palsy), asthenopia, headache, reading difficulty, and amblyopia in children with constant deviation. The Parks–Bielschowsky three-step test identifies the paretic vertical muscle by analyzing direction of greater hypertropia (right vs left gaze, head tilt right vs left).

Diagnostic workup includes uncover/cross-cover testing with prism, ocular motility examination, fundus torsion assessment, double Maddox rod testing for cyclotorsion, and orbital MRI/CT for restrictive or compressive causes. Treatment options include prismatic glasses (Fresnel or ground-in prism) for small deviations, occlusion or amblyopia treatment in children, strabismus surgery (inferior or superior oblique weakening, vertical rectus recess–resect) for larger deviations, and treatment of underlying cause (thyroid orbitopathy, fracture repair).