Acquired nystagmus

Nystagmus is the repetitive to and fro movement of the eyes, which may be physiological or pathological. The movements can be horizontal, vertical, torsional or a combination of these movements. It starts by a slow movement of the eye away from the visual target. The second movement brings the eye back to the visual target. If this second movement is quick, the nystagmus is called jerk nystagmus. If the second movement is slow, the nystagmus is said to be pendular. Maintaining steady gaze is dependent upon visual fixation, the vestibulo-ocular reflex and the gaze-holding neural integrator system. Pathological nystagmus typically presents with the symptom of oscillopsia, which is the illusory movement of the surrounding environment. Nystagmus that develops outside of early infancy is termed acquired nystagmus. There may be serious underlying pathology that will require further investigation and management. This article reviews the terminology, pathophysiology, causes and treatment of acquired nystagmus.

A Case Report of Nystagmus with Acute Comitant Esotropia Secondary to Heroin Withdrawal: A Novel Presentation

Background: Acute comitant esotropia secondary to heroin withdrawal is a rarely reported phenomenon that has never been described with nystagmus. Adverse effects of heroin on eye alignment were first reported in soldiers returning from Vietnam, yet no theory is generally accepted as the cause of these abnormalities. Method: We present a case of a 22-year-old female who developed 40 prism diopters of alternating comitant esotropia with nystagmus 8 days after abrupt heroin cessation, review the existing literature, and propose a novel hypothesis for this phenomenon. Results: After 76 days, her esotropia resolved, and she was left with 7 prism diopters of esophoria. Conclusion: This case demonstrates that acquired nystagmus can present in addition to acute-onset esotropia after abrupt heroin cessation. We compare and contrast the theories of this mechanism and review the literature.