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Wobbly eyes in infancy


Introduction

The infant with wobbly eyes is worrisome. While the majority have a benign etiology, this presentation may indicate severe neurological disease or even potentially lethal underlying malignancy. It is important therefore to have a diagnostic rationale for this problem. Here, I hope to share a concise clinical approach to the most common forms of nystagmus and ocular oscillations of infancy. The underlying diagnosis can be determined by history, clinical examination and with the proper investigation such as neuroimaging and/or electrophysiological testing (electroretinogram [ERG], visual evoked potential [VEP]). Optical coherence tomography (OCT) is an important adjunct to investigation; however, the feasibility of OCT in infancy in the outpatient setting for infants is difficult.

Classification

There are several ways of classifying nystagmus, each with relevant information to determine the differential diagnosis.

The nomenclature of the various eye movement disorders was revised in a collaborative effort by the NEI committee for the Classification of Eye Movement Abnormalities and Strabismus (CEMAS):

  • Description according to the phase: jerk vs. pendular type, named after the fast phase direction although the slow phase is the initial problem

    • Jerk: one fast, one slow phase

    • Pendular: phases are equal in amplitude and speed in both directions without a fast phase.

  • Axis of the fast phase: horizontal, vertical, torsional, or any combination.

  • Conjugate or dysconjugate: symmetric or asymmetric.

  • Time of onset: congenital or acquired.

  • Isolated or secondary to ocular diseases or neurological disease.

  • Distinction between sensory nystagmus from decreased vision and congenital motor nystagmus.

The distinction between the infantile nystagmus syndrome (INS) and an acquired nystagmus is essential because of the implication for associated neurological disease with acquired nystagmus.

Saccadic oscillations and intrusions

Opsoclonus and ocular flutter are not true nystagmus but are considered disorders of saccadic intrusions. They are back-to-back saccades without an intersaccadic interval and no refractory period. While opsoclonus saccades are multidirectional, ocular flutter is purely horizontal.

History

Clinical history

The clinical history can guide in the differential diagnosis of nystagmus. Pay attention to the following:

  • Prenatal: maternal diabetes or infections, substance drug abuse, alcohol. A history of maternal gestational diabetes, anticonvulsants, substance drug abuse can be associated with optic nerve hypoplasia.

  • Delivery: premature or traumatic birth, hypoxia.

  • Postnatal: intraventricular hemorrhage, retinopathy of prematurity (ROP) treatment.

  • Developmental delay, metabolic disorders, neurological disorders (seizures, cerebral palsy, Chiari malformation).

  • Onset: sensory nystagmus onset is between 2 and 4 months and is usually not present at birth. An acquired nystagmus can present after the age of 4 months.

Family history

The family history can suggest a genetic disorder in ocular conditions such as albinism, X-linked disorders, retinal disease, and the presence of nystagmus in other members of the family. A family history of poor vision, high refractive errors, or family members whose vision is not good enough to drive raises suspicion for a genetic disorder. A history of consanguinity increases the likelihood of autosomal recessive disorders.

Other family members can be affected, and in X-linked disease only males are affected. Patients with congenital stationary night blindness (CSNB), or blue cone monochromatism are affected with nystagmus. Infantile nystagmus is usually transmitted in an X-linked pattern caused by an FRMD7 mutation.

Symptoms

Photophobia or light sensitivity is an important symptom that can originate from anterior segment involvement, especially corneal disease, or from retinal diseases even if the retina appears relatively normal in the early stages of the disease. Extreme light sensitivity usually occurs in patients with achromatopsia or blue cone monochromatism.

Light gazing is also a symptom of poor vision. The infant is mesmerized by lights and this usually indicates poor vision, often arising from posterior visual pathway (post-geniculate) disease.

Night blindness or nyctalopia might be difficult to evaluate in infancy. In the toddler or older child parents might report that their child is afraid in the dark or scared in unfamiliar surroundings at night. This symptom is found in patients with CSNB or rod–cone dystrophy. Day blindness or hemeralopia is a common symptom in cone-related diseases such as cone dystrophy and Stargardt’s disease.

The oculodigital reflex or “visual self stimulation” is seen in patients whose poor vision is attributable to retinal disease. Eye pressing is thought to cause entoptic photopsias, in patients with severely reduced vision such as in Leber’s congenital amaurosis (LCA) or bilateral stage 5 ROP.

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