Nystagmus in Infancy

Definition and Characteristics of Nystagmus

• Nystagmus is characterized by involuntary, rhythmic eye oscillations disrupting steady fixation and affecting visual acuity.
• Normal eye appearance, but constant movement results in poor vision.
• Key parameters include:
  • Direction: fast phase orientation (horizontal, vertical, cyclorotary)
  • Amplitude: size of oscillation
  • Frequency: number of cycles per second
  • Intensity: product of amplitude and frequency
  • Waveform types: jerk, pendular, complex
  • Conjugacy: can be conjugate (associated) or disconjugate (dissociated)
  • Null point: position where nystagmus intensity is minimal; induces compensatory head posture.
  • Foveation: slow eye movements allowing for better visual acuity.

Congenital Motor Nystagmus

• Onset occurs within the first six months of life, can be sporadic or autosomal dominant.
• Usually presents as purely horizontal in all gaze positions, and vision often remains relatively good without oscillopsia.
• Waveform can be pendular or jerk, with dampening upon convergence.
• Patients may develop a null point, leading to compensatory head turns.
• Visual acuity typically ranges from 20/40 to 20/80, depending on intensity and frequency.

Funblocs and Latent Nystagmus

• Funblocs involve factors like worsening fixation and maintaining horizontal gaze, often requiring subtle head movements.
• Latent nystagmus typically occurs in cases of congenital esotropia or early vision loss; it manifests more clearly when one eye is occluded.

Sensory Nystagmus

• Occurs due to severely impaired vision (worse than 20/200), often presents as a pendular pattern but can be jerky.
• Associated with various conditions: cataracts, corneal opacity, chorioretinal coloboma, retinopathy of prematurity (ROP), aniridia, optic nerve hypoplasia, albinism, and cone dysfunction.

Pathologic Nystagmus

• Acquired nystagmus in children should prompt neurological evaluation to rule out underlying issues.

Causes of Sensory Nystagmus

• Common etiological factors include congenital cataracts, corneal opacity, aniridia, Leber's congenital amaurosis, optic atrophy, achromatopsia, and ROP.

Types of Nystagmus

• Spasmus Nutans:
  • Occurs after six months of age and typically resolves by ages four to five.
  • Features include pendular nystagmus, head nodding, and torticollis.
  • Presents as disconjugate and can be mistaken for monocular involvement, with a low amplitude and high frequency, described as "shimmering."
  • Considered benign but requires ruling out all pathologic causes.

Treatment Options for Nystagmus

• Optical Treatment:

  • Base-out (BO) prisms utilized if convergence dampens nystagmus significantly.
  • Yoked prisms can assist with eccentric null points.
  • Contact lenses may be prescribed.

• Surgical Treatment:

  • Anderson-Kestenbaum procedure and Cuppers artificial divergence procedure.
  • Large recessions of the horizontal rectus muscles are implemented.
  • Hertle-Del’Osso procedure for additional corrective measures.

• Pharmacological Treatment:

  • Botulinum toxin injections are considered for management in specific cases.

This quiz explores nystagmus, a condition characterized by involuntary, rhythmic oscillation of the eyes, particularly as it presents in infancy. Understand the implications for visual acuity and diagnosis, as well as the differences between normal eye movement and nystagmus. Gain insights into how this condition affects infants and the speed of eye movements.