Decision making in a patient with hypotropia has identified paralysis of a superior rectus muscle. Further diagnostic maneuvers are now required to confirm the diagnosis and exclude similar conditions.

The differential diagnosis of a superior rectus muscle paralysis includes mechanical causes that limit elevation of the eye, such as contracture, fibrosis, high myopia (heavy eye), myositis, endocrine orbitopathy, or a blow-out fracture of the orbital floor . Whenever elevation is restricted mechanically the forced duction test will be positive, and the restriction often involves the entire upper field of gaze.

The head tilt test  is less consistent in vertical rectus paralyses than in oblique muscle paralyses.

 Measuring the deviation with either eye fixing may be useful. The contralateral inferior oblique muscle overacts when the patient fixates with the paralyzed eye in elevation and abduction (secondary deviation) .

Superior rectus muscle paralysis is frequently but not always associated with weakness of the homolateral levator palpebrae muscle, particularly if the paralysis is congenital. Since the upper lid elevates with elevation of the globe and drops when the eye moves downward, a true ptosis caused by levator weakness must be differentiated from pseudoptosis secondary to the hypotropic position of the globe , which is the case in this patient

Superior rectus paralysis may be associated with weakness of the ipsilateral levator palpebrae muscle, in which case a true ptosis is present. In other cases, levator function may be essentially normal and pseudoptosis is present, caused by the depressed position of the paretic eye. In that case, the upper lid elevates normally when the sound eye is covered.

But in SO palsy when the eye with the paretic superior oblique is used for fixation the yoke inferior rectus in the contralateral eye receives extra innervation. Its antagonist, the superior rectus and also the levator palpebri on that side are inhibited resulting in hypotropia and more importantly, pseudoptosis. When the normal eye takes up fixation, the ptosis disappears.

A superior rectus paralysis frequently causes a head tilt with chin elevation. However, the direction of the head tilt (i.e., to the right or left shoulder) is inconsistent and therefore of no diagnostic value.

Patients with trochlear palsy who habitually fixate with their paralyzed eye have a pseudoparalysis of the contralateral superior rectus muscle (inhibitional palsy of the contralateral antagonist).^{58, p.367} The Bielschowsky head tilt test distinguishes between these two conditions

Depending on the comitance of the deviation and on whether secondary contracture of the ipsilateral inferior rectus muscle has developed, resection of the superior rectus is combined with recession of its antagonist.^{58, p.393} In paralysis of both elevator muscles (double elevator paralysis), the insertions of both horizontal rectus muscles are transposed to the insertion of the superior rectus muscle (Knapp procedure), provided the forced duction test is negative. In other cases, resection of the paretic superior rectus may be combined with recession of the contralateral superior rectus.