Recommended Reading – Treatment of Nystagmus and Saccadic Oscillations

Treatment of Nystagmus and Saccadic Oscillations
Matthew J. Thurtell, and John J. Brinkley/ University of Iowa. EyeRounds.org. 2013
http://webeye.ophth.uiowa.edu/eyeforum/tutorials/Nystagmus/

Introduction
Nystagmus is often encountered in ophthalmology practice, having a prevalence of about 24 per 10,000 in the general population.[1] Unlike physiologic nystagmus, where the slow phases of nystagmus minimize retinal image slip, the slow phases of pathologic nystagmus cause retinal image slip. Retinal image slip of greater than 5 degrees per second produces a decline in visual acuity, partly because the image of the object of interest no longer lies on the fovea, and illusory motion of the visual environment known as oscillopsia.[2,3] Saccadic intrusions and oscillations can also cause visual symptoms, such as difficulty reading, since they take the eye off target so that the image of the object of interest no longer lies on the fovea.[2]

Goals of Treatment
The goal of treatment is to reduce visual symptoms (e.g., blurred vision, oscillopsia) by reducing the speed of nystagmus slow phases or by suppressing saccadic oscillations. Treatments that stop the eyes from moving altogether (e.g., botulinum toxin injections into the extraocular muscles) are not ideal, because they cause oscillopsia during head movements (due to loss of the vestibulo-ocular reflex) and diplopia (due to loss of vergence eye movements).[2] Thus, treatments that suppress the abnormal eye movements without affecting normal eye movements are preferred. Note that some types of nystagmus (e.g., gaze-evoked) and saccadic intrusions (e.g., square-wave jerks) do not usually give visual symptoms and, thus, do not require specific treatment.

General Approaches to Treatment
Treatments for nystagmus that have been proposed include medical, optical, surgical, and other miscellaneous treatments (Table 1); few of these have been evaluated in prospective masked clinical trials.[2,4] Likewise, a variety of treatments for saccadic oscillations have been proposed; few have been evaluated in prospective masked clinical trials.[2] Most treatments aim to suppress the abnormal eye movements without affecting normal eye movements, whereas others aim to negate the visual consequences of the abnormal eye movements. Choice of treatment depends on the type of nystagmus or saccadic oscillation and its characteristics. While some patients will derive benefit from one treatment approach, others require a combination of treatments.[2,4]

Full Article http://webeye.ophth.uiowa.edu/eyeforum/tutorials/Nystagmus/