Trochleitis is diagnosed based on three criteria: 1) demonstration of inflammation of superior oblique tendon/ trochlea region, 2) periorbital pain and tenderness to palpation in the area of the sore trochlea, and 3) worsening of pain on attempted vertical eye movement, particularly with adduction of the eye. It is important to identify trochleitis because it is a treatable condition and the patient can benefit much from pain relief. Treatment consists of a single injection of corticosteroids to the affected peritrochlear region. A specific "cocktail" consisting of 0.5 ml of depomedrol (80 mg/ml) and 0.5 ml of 2% lidocaine can be injected into the trochlea; immediate relief due to the effects of the local anesthetic indicates successful placement. However, great care must be taken as the injection is in the region of several arteries, veins and nerves. The needle should not be too small (so as not to penetrate tiny structures), the surgeon should draw back on the syringe (to ensure not have pierced a vessel), the lidocaine should not contain epinephrine (which could cause vasospasm), and the pressure of the injection must always be controlled. Only a limited number of injections can be made as they would otherwise lead to muscle atrophy. Diagnosis can be confirmed by response to this treatment; pain and swelling are expected to disappear in 48–72 hours. Some patients experience recurrence of trochleitis.

Trochleitis was first identified in 1984 by Tychsen, et al. in a study of thirteen patients with orbital pain and point tenderness over the trochlear region. Previously, the trochleitis syndrome had been included in the broad category of idiopathic orbital inflammation (also called orbital pseudotumor). From the study, Tychsen and his group surmised that trochleitis was a subtype of idiopathic orbital inflammation distinct from the larger category in that it produced little/ no discernible ocular signs (the eye looked normal) and did not cause restricted extraocular movement.