Nystagmus is a vision condition involving rhythmic, regular movements of the eyes. The characteristic pattern of nystagmus distinguishes it from other abnormal involuntary eye movements. These movements can reduce vision and affect depth perception, balance, and coordination. The eye movements can be paroxysmal, continuous, or caused by such things as changes in gaze or head positioning. Often, nystagmus can be seen transiently, which may indicate some type of underlying pathology. Nystagmus can also be labeled as manifest, latent, or a combination of the two. Manifest nystagmus is always present. Latent nystagmus occurs when covering one eye. Manifest-latent nystagmus is always present but worsens when one eye closes.
There are two basic types of nystagmus including optokinetic (also known as pendular nystagmus) and vestibular (also known as jerk nystagmus). Pendular nystagmus can occur in any direction – torsional, horizontal, vertical, or a combination of these. This type of nystagmus can be monocular or binocular and can differ in both eyes. A characteristic finding with optokinetic nystagmus is that it occurs without fast phases. Comparatively, vestibular nystagmus has a fast phase and classifies according to the direction of the fast phase. With vestibular nystagmus, eyes drift slowly in one direction and then jerk back in the other direction. This nystagmus can be upbeat, downbeat, horizontal, or mixed and is more common than optokinetic nystagmus.
The age of the individual exhibiting nystagmus can help determine the underlying causes. For example, infantile nystagmus usually develops by three months of age. In most instances, it is a horizontal movement and has correlations with conditions such as albinism, congenital iris absence, underdeveloped optic nerves, or congenital cataract. Children age 6 months to 3 years can have a form of nystagmus known as spasmus nutans. This form usually improves without intervention between ages 2 through 8 years. Characteristically, children will often nod or tilt their heads with this type of nystagmus, and the eyes may move in any direction. Acquired causes of nystagmus require exploration if the eye movements develop later in life.
Nystagmus in some patients can be asymptomatic. However, in the majority, nystagmus causes vertigo, oscillopsia, blurred vision, or abnormal head positioning. Vertigo is the primary symptom and occurs most commonly with vestibular problems. Oscillopsia, which is a sensation of the environment moving back and forth, depends on the type of nystagmus present but can be continuous, intermittent, or gaze-evoked. Blurred vision usually occurs due to the retinal image being affected by the motion. This blurred vision can lead to abnormal head positioning, which is when patients compensate for their vision changes by finding gaze positions that minimize their symptoms.
A major concern with finding nystagmus on the clinical exam is determining the cause. For instance, acquired nystagmus which develops later in adolescence or adulthood and can indicate a central nervous system issue like multiple sclerosis, head injury, brain tumor, metabolic disorder, medication side effect, hyperventilation, or even alcohol or drug toxicity.
The differential diagnosis of nystagmus also includes oculogyric crises and ocular bobbing. Oculogyric crises are distinguishable from nystagmus by noting a lack of a specific rhythm or slow phase with the eye movements. This type of eye movement most commonly presents with phenothiazine intoxication. Ocular bobbing is more irregular than nystagmus and usually occurs in locked-in syndrome.
|||Dell'Osso LF,Schmidt D,Daroff RB, Latent, manifest latent, and congenital nystagmus. Archives of ophthalmology (Chicago, Ill. : 1960). 1979 Oct; [PubMed PMID: 485910]|
|||Gresty MA,Ell JJ,Findley LJ, Acquired pendular nystagmus: its characteristics, localising value and pathophysiology. Journal of neurology, neurosurgery, and psychiatry. 1982 May; [PubMed PMID: 7086456]|
|||Baloh RW,Spooner JW, Downbeat nystagmus: a type of central vestibular nystagmus. Neurology. 1981 Mar; [PubMed PMID: 6970904]|
|||Young TL,Weis JR,Summers CG,Egbert JE, The association of strabismus, amblyopia, and refractive errors in spasmus nutans. Ophthalmology. 1997 Jan; [PubMed PMID: 9022113]|
|||ANDERSON JR, Causes and treatment of congenital eccentric nystagmus. The British journal of ophthalmology. 1953 May; [PubMed PMID: 13042022]|
|||Rushton D,Cox N, A new optical treatment for oscillopsia. Journal of neurology, neurosurgery, and psychiatry. 1987 Apr; [PubMed PMID: 3585351]|
|||Masucci EF,Kurtzke JF, Downbeat nystagmus secondary to multiple sclerosis. Annals of ophthalmology. 1988 Sep; [PubMed PMID: 3190116]|
|||Tilikete C,Jasse L,Pelisson D,Vukusic S,Durand-Dubief F,Urquizar C,Vighetto A, Acquired pendular nystagmus in multiple sclerosis and oculopalatal tremor. Neurology. 2011 May 10; [PubMed PMID: 21555732]|
|||Schmidt D,Kommerell G, [Seesaw nystagmus with bitemporal hemianopia following head traumas]. Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie. Albrecht von Graefe's archive for clinical and experimental ophthalmology. 1969; [PubMed PMID: 5307804]|
|||Hübner J,Sprenger A,Klein C,Hagenah J,Rambold H,Zühlke C,Kömpf D,Rolfs A,Kimmig H,Helmchen C, Eye movement abnormalities in spinocerebellar ataxia type 17 (SCA17). Neurology. 2007 Sep 11; [PubMed PMID: 17846415]|
|||Fish DJ,Rosen SM, Epidural opioids as a cause of vertical nystagmus. Anesthesiology. 1990 Oct; [PubMed PMID: 2221451]|