Pediatric nystagmus is a common reason for referral to an ophthalmologist or neurologist; however, new-onset nystagmus is a rare and alarming presentation when seen in emergency departments (EDs) (1). This case involves a 2-month-old male who presented to an urban pediatric ED with new-onset positional nystagmus and was diagnosed with primary congenital glaucoma (PCG). To the authors’ best knowledge, there is a paucity of cases reporting infantile nystagmus as the presenting symptom of PCG. By understanding this chief complaint, the differential diagnosis, and the appropriate workup, there would be an opportunity to reduce the use of magnetic resonance imaging (MRI) or hospitalization in patients without red-flag symptoms, such as altered mental status, gait or balance disturbance, neurological abnormalities, or delayed development (2). The legal guardians of the patient provided informed consent to share the details of this case.

The 2-month-old male, born full-term via uncomplicated vaginal delivery, presented to a large, urban pediatric ED with new abnormal eye movements, as reported by the parents. Three days prior to the visit, they noticed the rapid eye movements lasting 5-30 seconds, primarily when he was placed in the supine position. He had otherwise been developing as expected without other abnormal ocular or motor movements. The parents described a “glaze”over both eyes since birth, which had never changed nor had been evaluated by a medical provider. There was no reported decrease in feeding, vomiting, fever, or persistent fussiness. Family history revealed asthma and anemia in his mother as well as hyperten-sion in his grandparents on her side. There was no known family history of metabolic or genetic disorders.

The initial vital signs were as follows: blood pressure, 96/42 mmHg; heart rate, 172 beats/minute; respiratory rate, 52 breaths/minute; and temperature, 37.4 ^。C. On physical examination, the patient was alert, well-looking, and acting appropriately for his age, moving all extremities equally. The anterior fontanelle was open and flat, and muscular tone was normal. Eye examination revealed cloudy corneas bilaterally. Although extraocular movements were intact, it was difficult at his age to assess whether he was able to track an object appropriately during the examination. Upon laying him supine, there was reproducible, intermittent, large-amplitude, conjugate vertical nystagmus for approximately 5 seconds. Following resolution of the nystagmus, he returned to baseline with no additional abnormal extraocular movements.

After consultation with a pediatric neurologist and ophthalmologist, brain MRI and laboratory tests were deferred during the initial visit. The patient was achieving developmental milestones, appeared otherwise well, and had no other concerning features on physical examination (e.g., bicycling of legs, decreased muscular tone, strabismus, or lethargy). Given these reassuring features, his clinical picture appeared to be more consistent with an isolated eye disorder, rather than seizure-like activity, metabolic abnormalities, or other intracranial pathologies.

On the bedside ophthalmic examination, the patient was noted to respond to light stimuli appropriately in each eye and did not appear to have photophobia. Intraocular pressure (IOP) measured by a handheld applanation tonometry was at 60 mmHg (oculus dexter [OD]) and 45 mmHg (oculus sinister [OS]), elevated above the age-related reference value of 9.1 ± 2.9 mmHg (3). There was moderate bilateral corneal edema, indicating early buphthalmos, and a dilated fundoscopic examination revealed an optic cup-to-disc ratio of 0.5 (reference value, < 0.3 [4]). The constellation of ocular findings was consistent with PCG, which caused a visual deprivationinduced nystagmus. He was discharged on the same day with ophthalmic 0.25% timolol and 2% dorzolamide as temporary medications, and urgently referred to a pediatric glaucoma specialist.

Three days following the initial visit, the patient underwent the glaucoma specialist’s examination under anesthesia. Despite the use of the aforementioned topical medications, his IOP remained at 30.4 mmHg (OD) and 23.7 mmHg (OS). Gonioscopy showed a“ hazy view”and“ flat iris insertion”on all views, findings indicative of corneal edema and anomaly of the trabecular meshwork. Central corneal thickness measured on pachymetry was 710 μm (OD) and 707 μm (OS), thicker than the age-related reference value of 544 μm (5). The fundus examination revealed “cupped”optic nerves bilaterally (Figure). Bilateral trabeculectomy was performed without a complication.

On post-operative days 1, 6, and 27, the patient showed normal IOP and routine post-operative healing. The parents declined genetic testing related to PCG. Since the operation, he has remained developmentally normal and continued ophthalmology follow-up. There were no further reports of abnormal eye movements per clinician documentation, and corneal haziness and optic nerve cupping have resolved.

This case is unique in the discussion of PCG because the presenting chief complaint was nystagmus rather than more common symptoms such as epiphora, photophobia, blepharospasm, or buphthalmos. In this discussion, we will review the differential diagnosis of pediatric nystagmus, including the appropriate workup, as well as the diagnosis and treatment of PCG.

The differential diagnosis of pediatric nystagmus varies depending on the age of presentation. An infant who presents with nystagmus within the first 6 months of life is considered to have infantile nystagmus (2). From an emergency medicine perspective, it is essential that neurologic and ocular categories be discerned among the numerous other etiologies of such nystagmus.

Neurological causes of pediatric nystagmus, which account for 2% of infantile nystagmus cases, include congenital brain tumors and other brain anomalies, such as encephalocele or Chiari malformation, and other malpositions of the cerebellar tonsil (1). Vertical nystagmus, as seen in the case patient, is most often associated with neurological abnormalities (6). However, he was otherwise developing normally with no neurological abnormalities. Given the presence of isolated ophthalmic findings, neuroimaging was deferred. This case suggests the importance of considering causes of infantile nystagmus aside from neurological abnormalities, particularly in the absence of other neurologic symptoms such as strabismus, cranial nerve deficit, or ataxia. In an Iowa hospital, among 202 patients with infantile nystagmus, 74 (36.6%) underwent MRI as their first test. In the group of patients, 28 with isolated nystagmus had a 0% diagnostic yield, while the other 46 with neurologic signs had a 30% yield (1). Although less likely, a minority of patients may have isolated vertical nystagmus without overt neurological abnormalities (7). Therefore, if there had not been a clear abnormality intrinsic to the eye noted on examination of our patient, neuroimaging would have been pertinent for further evaluation.

Ocular etiologies include any condition that causes bilateral visual deprivation (e.g., cataracts, optic nerve hypoplasia, or corneal opacities) or genetic conditions (albinism, Leber congenital amaurosis, or other retinal dystrophies) (1). In this patient, PCG caused a corneal opacity that resulted in visual deprivation-induced nystagmus. In the Iowa study, a complete pediatric ophthalmic examination was able to detect the cause of the nystagmus in 67% of the cases, later confirmed by specialized ophthalmic testing such as electroretinogram or optical coherence tomography if needed (1).

PCG is rare among the causes of visual deprivation in infants. The incidence of PCG varies widely across different geographic groups, with studies from Western countries (e.g., Ireland, Britain, or the United States) reporting rates of 1:10,000-70,000 (8). There is a much higher incidence (1:2,500-3,300) in Saudi Arabia, Southern India, and the Roma population in Slovakia, thought to be secondary to the high incidence of consanguinity in these populations (8). PCG is caused by genetic variants that are autosomal recessive with incomplete penetrance; thus, most cases occur without a family history of PCG (9). The classic triad of symptoms includes epiphora, photophobia, and blepharospasm (9). On examination, a provider should determine the patient’s ability to fixate and follow a light, as well as closely examine the sclera and cornea for signs of buphthalmos (9). Evaluating IOP is critical as it is usually elevated with this diagnosis. Although not every ED has a 24/7 access to ophthalmologic consultation, patients with possible PCG should be urgently referred to an ophthalmologist.

The initial treatment of PCG consists of topical medications to lower IOP and decrease corneal edema until surgical intervention is performed (9). Topical medications, such as alpha-adrenergic agonists, beta-blockers, or carbonic anhydrase inhibitors, act by decreasing aqueous production and therefore decreasing IOP (9). Goniotomy or trabeculectomy is the gold standard intervention used to alleviate IOP by improving aqueous outflow with a 70%-90% success rate (9).

The prognosis of PCG depends on the disease severity, age of presentation, and corneal clarity at the time of diagnosis. Early diagnosis and management are of utmost importance for vision preservation, as corneal edema and optic nerve head changes are reversible if there is a timely intervention (9). These patients do require lifelong monitoring of IOP and the optic nerve head, as studies have demonstrated gradual disease progression throughout life (10).

This case report highlights a rare diagnosis of new-onset infantile nystagmus secondary to PCG. This serves as a relevant case that teaches the appropriate workup and evaluation of nystagmus, potentially decreasing the use of neuroimaging and hospitalization when a patient has otherwise normal neurological findings and an abnormality noted intrinsic to the eyes. Appropriate subspecialty consultation is essential in establishing the diagnosis and subsequently reducing vision-related morbidity associated with delayed diagnosis and management.