Background and Purpose: Torsional diplopia can result in failure of fusion in an individual without a measureable strabismus. When presented with a patient with complaints of binocular diplopia, physicians and orthoptists should consider cyclovertical muscle dysfunction when the source of the complaint is not readily apparent. Methods: A thorough review of the literature combined with the author's own personal experience in treating adult patients with strabismus was used to evaluate the different potential causes of torsional diplopia. Predisposing factors, diagnostic techniques, and strabismus diagnoses are considered. Results: The most common cause of torsional diplopia is a superior oblique palsy. Other more common causes include thyroid-related orbitopathy and skew deviations. Conclusions: Torsional diplopia is a common cause of undiagnosed strabismus in the adult patient population. Proper consideration of the most common causes should be made.
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