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Comprehensive Overview of Nystagmus: Mechanisms, Types, and Management

Detailed presentation covering definition, mechanisms, classification, causes, symptoms, evaluation, and treatment options for nystagmus, including congenital and acquired forms.

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NYSTAGMUS Presented by- Nasir uddin
 Definition  Mechanisms  Causes  Symptoms  Classification  History taking  Evaluation  Management and Treatment CONTENT
DEFINITION • Nystagmus is a regular, repetitive, involuntary movement of the eye whose direction, amplitude and frequency is variable. • It may be physiological or pathological or idiopathic • May be early onset or later onset.
MECHANISMS Three mechanism maintaining foveal centration of an object are - • Fixation –The visual system detects drift in the foveating image (the image focused on the retina) and signals corrective eye movements to refoveate the image. If this system is disrupted, it can lead to involuntary eye movements • Vestibulo-ocular reflex(VOR)-This reflex is crucial for stabilizing vision during head movements. It allows the eyes to move in the opposite direction of head motion, maintaining a stable image on the retina. Disruption in this reflex can lead to nystagmus. • Neural integrators-This mechanism helps maintain eye position during eccentric gaze (looking away from the center). If the neural integrator is impaired, it can result in difficulty holding the gaze, contributing to nystagmus.
• Saccades: Saccades are rapid conjugate eye movements performed to bring the image of an object quickly on the fovea. Eg: reading, writing. • Pursuits: Pursuits movement are made when tracking a moving object. It helps to keep the image of a moving object on the fovea constantly. Eg: it is performed while watching a bird which is moving right, left, up & down. Normal eye movements
Frequency Frequency is the no. of to and fro movement in one second. Described as cycles/secs or Hertz(Hz) Slow:1-2Hz Medium:3-4Hz Fast:5Hz or more
Amplitude is the angular distance traveled during nystagmus (excursion of the nystagmus) • Low : less than 5 Degree • Moderate: 5-15 Degree • High: > 15 Degree Amplitude
It states that the amplitude of jerk nystagmus is largest in the gaze of direction of fast component. • 1 degree: nystagmus only in the direction of the fast component. • 2 degree: nystagmus in primary gaze position. • 3 degree: nystagmus in addition to above gazes, also present in the direction of the slow component. Alexander’s Law
Types of Nystagmus based on movement characteristics
Types of Nystagmus based on eye movement
• Horizontal Nystagmus: It refers to involuntary eye movements that occur side-to-side, along the horizontal plane. It's one of the most common forms of nystagmus and is often seen in conditions like vestibular disorders, neurological diseases, or as a medication response. • Vertical Nystagmus: In vertical nystagmus, the eyes move up and down. This type is less common and often points to a central nervous system issue, such as brainstem or cerebellar lesions. It can be upbeat (eyes drift down and jerk upwards) or downbeat (eyes drift up and jerk downwards). • Rotary nystagmus: It is also known as circular or torsional nystagmus. when the eyes rotate around the visual axis. It occurs with vestibular dysfunction or inner ear disturbances. Nystagmus with a torsional component is frequently observed along with other types of nystagmus.
Conjugate- Nystagmus which is symmetric in direction, amplitude & rate between two eyes. Disconjugate- Direction of oscillations differ between two eyes.
Types of Nystagmus based on cause
Physiological Nystagmus This is further classified as- OKN: it is physiological jerk nystagmus induced by presenting to gaze objects serially in one direction, such as strips of a spinning optokinetic drum. EGN: it is a fine jerk horizontal nystagmus seen in normal persons on extreme right or left gaze.  VOR: it is a jerk nystagmus which can be elicited by stimulating the tympanic membrane with hot or cold water. This is the basis of caloric test. (COWS- cold opposite and warm same)
Congenital Nystagmus These are classified as: A. Afferent or sensory nystagmus B. Idiopathic infantile nystagmus C. Latent/latent manifest nystagmus D. Spasmus nutans Pathological Nystagmus
A. Afferent or Sensory Nystagmus: It is also known as congenital ocular nystagmus and is usually associated with sensory deprivation due to: • Ocular albinism • Bilateral congenital cataract • Aniridia • Bilateral optic nerve hypoplasia. B. Idiopathic infantile nystagmus: It is also known as idiopathic congenital nystagmus. It is characterised by: • Hereditary, • Onset -very early, usually by two months of age.
C. Latent/Manifest latent nystagmus: It is not present when both eyes are open. It is present only when one eye is closed. It is a jerk nystagmus, with the rapid phase towards the uncovered eye. Associated with congenital esotropia. D. Spasm nutans: It is a fine pendular horizontal nystagmus associated with head nodding and abnormal head posture. It’s onset is in infancy and self-resolves by the age of 3 years.
Acquired Nystagmus Acquired nystagmus develops later in life due to underlying medical issues. It can be horizontal, vertical, or rotary and may worsen with certain activities or positions. Neurological disorders (e.g., multiple sclerosis, stroke), head injuries, or drug and alcohol intoxication are the most common causes of acquired nystagmus.
Acquired Nystagmus Acquired nystagmus develops later in life due to underlying medical issues. It can be horizontal, vertical, or rotary and may worsen with certain activities or positions. Neurological disorders (e.g., multiple sclerosis, stroke), head injuries, or drug and alcohol intoxication are the most common causes of acquired nystagmus.
History Taking Congenital/acquired H/O oscillopsia Visual behaviour of child H/O poor vision Any associated abnormal head posture Any neurological problem H/O photophobia F/H/O similar problem
Evaluation Type: Rotatory, see-saw, jerk, pendular Pattern: Horizontal, torsional, vertical Frequency: fast/slow Amplitude: Fine/medium/large Direction: down/ up/left/right Symmetry: Yes/no Face turn: Right/left Head tilt: Right/left Head nodding: Yes/no
NYSTAGMUS Which eye Head Nodding Type Pattern Frequency Amplitude Direction Symmetry Face turn Head tilt
• Optical correction(glass or contact lens) • Prism lens • Medications • Surgery(rarely) Management & treatment of nystagmus
Comprehensive Overview of Nystagmus: Mechanisms, Types, and Management