Treatment of abnormal eye movements that impair vision: Strategies based on current concepts of physiology and pharmacology

Abstract

Certain abnormal eye movements, especially pathological nystagmus, degrade vision and cause illusory motion of the seen environment. These symptoms are due to excessive movement of images of stationary objects on the retina. Recently, the pathophysiology underlying several types of nystagmus and saccadic oscillations was better defined by the development of animal models and by experimental pharmacological studies. Despite this, few reliable therapies are currently available for these abnormal eye movements. In clinical studies, a number of drugs reportedly helped individual patients, but few drugs have been subjected to double-blind trials. An alternative approach to pharmacological suppression of abnormal eye movements is optical stabilization of images on the retina, which is helpful in selected patients. Weakening of the extraocular muscles, using botulinum toxin or surgery, is prone to cause diplopia and may induce plastic-adaptive changes that render the effect temporary. In some patients, treatment of an underlying condition, such as the Arnold-Chiari malformation, reduces nystagmus and improves vision. There is a need for multicenter trials to evaluate systematically potential treatments of abnormal eye movements that impair vision.

Drug therapy for acquired pendular nystagmus in multiple sclerosis

“…One reason for the controversy is the poorly understood pathophysiology of APN. Several of the following possible factors have been proposed: (1) spontaneous oscillations of neurons in the inferior olive [26], which are denervated after lesions of the dentato-rubro-olivary pathways [27,38,40]; (2) lesions of the deep cerebellar nuclei [25]; (3) lesions of retino-tectal pathways; (4) lesions in the vicinity of the oculomotor nuclei [13]; (5) and abnormalities of 13 Fig. 2 Dose-dependent effect of memantine on the amplitude of APN (patient 9; original monocular DC-EOG recordings; eyes open, fixation straight ahead).…”

Evaluation of the visual function of patients with locked-in syndrome: Report of 13 cases

“…In the latter, oscillopsia occurs even when the head is still. The magnitude of oscillopsia is usually inferior to the magnitude of the nystagmus [4]. Paresis and abnormalities of the vestibulo-ocular reflex are only reported in patients who suffered from incomplete LIS form with preserved head movements.…”

“…The best visual acuity is obtained if the object projects within 0.5 degrees from the center of the fovea [4]. Oscillopsia is usually caused by excessive motion of images of stationnary objects upon the retina.…”

The use of contact lenses to treat visually symptomatic congenital nystagmus

“…1 It is possible that a true damping effect would be more obvious in patients with acquired nystagmus and severe oscillopsia than in patients with congenital nystagmus. 4 There are problems with the use of contact lenses in nystagmus. Fitting is technically difficult and requires multiple measurements of keratometry.…”