Purpose of review: "Double vision" is a commonly encountered concern in neurologic practice; the experience of diplopia is always sudden and is frequently a cause of great apprehension and potential disability for patients. Moreover, while some causes of diplopia are benign, others require immediate recognition, a focused diagnostic evaluation, and appropriate treatment to prevent vision- and life-threatening outcomes. A logical, easy-to-follow approach to the clinical evaluation of patients with diplopia is helpful in ensuring accurate localization, a comprehensive differential diagnosis, and optimal patient care. This article provides a foundation for formulating an approach to the patient with diplopia and includes practical examples of developing the differential diagnosis, effectively using confirmatory examination techniques, determining an appropriate diagnostic strategy, and (where applicable) providing effective treatment.
Recent findings: Recent population-based analyses have determined that diplopia is a common presentation in both ambulatory and emergency department settings, with 850,000 such visits occurring annually. For patients presenting to an outpatient facility, diagnoses are rarely serious. However, potentially life-threatening causes (predominantly stroke or transient ischemic attack) can be encountered. In patients presenting with diplopia related to isolated cranial nerve palsy, immediate neuroimaging can often be avoided if an appropriate history and examination are used to exclude worrisome etiologies.
Summary: Binocular diplopia is most often due to a neurologic cause. The onset of true "double vision" is debilitating for most patients and commonly prompts immediate access to health care services as a consequence of functional impairment and concern for worrisome underlying causes. Although patients may seek initial evaluation through the emergency department or from their primary care/ophthalmic provider, elimination of an ocular cause will not infrequently result in the patient being referred for neurologic consultation. A logical, localization-driven, and evidence-based approach is the most effective way to arrive at the correct diagnosis and provide the best outcome for the patient.