Similar to examination for retinal hemorrhages, evaluation of the optic nerve is often difficult in pediatric patients, particularly infants and toddlers. In older children, examination of the nerve may be part of the routine well-child examination, or may be performed due to specific symptoms (such as headache). The presence of papilledema requires prompt evaluation, including neuroimaging and consultation with a neurologist. If the patient has an abnormal-appearing nerve, but no symptoms of increased intracranial pressure, referral to a pediatric ophthalmologist should be considered to evaluate for pseudopapilledema, which could obviate the need for further extensive testing. Most children with other abnormal optic nerve findings should be referred to a pediatric ophthalmologist.

What Shouldn’t Be Missed

Optic nerve hypoplasia is a frequent cause of very poor vision and nystagmus in infants. Due to the difficulty of direct ophthalmoscopic evaluation of the optic nerves in infants with nystagmus, such patients require referral to a pediatric ophthalmologist. Optic nerve hypoplasia may be associated with pituitary abnormalities, and these patients may be unable to mount a normal stress response, potentially causing severe problems during even mild illnesses. This possibility should be kept in mind until the patient is evaluated by an endocrinologist.

Papilledema may occur in patients with idiopathic intracranial hypertension. In children, this is most commonly associated with medication use, such as corticosteroids or retinoic acid. Prompt evaluation is indicated to rule out intracranial tumors or other abnormalities and minimize the risk of vision loss associated with untreated papilledema.

• 1. Optic nerve hypoplasia. Optic nerve hypoplasia is a common cause of decreased vision in infants (Figure 21–1). This diagnosis usually cannot be made by the pediatrician due to the difficulty examining the optic nerves in infants with nystagmus. However, this potential diagnosis should be kept in mind while the evaluation is in progress, due to the risk of associated pituitary problems.
  
• 2. Papilledema. True papilledema usually results from increased intracranial pressure (Figure 21–2). This may occur due to space-occupying lesions, trauma, or idiopathic intracranial hypertension (pseudotumor cerebri) (Table 21–1). It may also arise due to tumors within the optic nerve (Figure 21–3A and B). The finding of papilledema warrants prompt evaluation.
  
• 3. Optic nerve coloboma. Optic nerve colobomas result from incomplete closure during the embryonic development of the eye (Figure 21–4). They are widely variable, both in appearance and in visual consequences.
  
• 4. Glaucoma. In infants and young children with glaucoma, the initial signs and symptoms include enlargement of the eye, corneal clouding, and light sensitivity. In older children and adults, the eye does not grow in response to increased intraocular pressure. The pressure causes damage to the optic nerve, producing an increase in the cup:disc ratio (Figure 21–5A and B). The vision loss affects the peripheral visual field first, with gradual constriction until the central vision is affected. Therefore, patients may have substantial loss of vision before the problem is detected. This is why glaucoma is sometimes called “the sneak thief of sight.” This type of minimally symptomatic glaucomatous visual loss is much more common in adults (particularly the elderly) than in children.
  
• 5. Pseudopapilledema. The term pseudopapilledema describes patients who have an abnormality of the nerve with an appearance suggesting possible increased intracranial pressure (Table 21–2). Common causes include optic disc drusen (Figure 21–6) and Trisomy 21 (Figure 21–7). It is important to differentiate this abnormality from true papilledema, in order to avoid unnecessary testing.
  
• 6. Myelinated nerve fibers. This abnormality has a very distinctive appearance, with white, feathery opacities adjacent to the optic nerve (Figure 21–8). The myelinated nerve fibers themselves do not cause vision problems, but they are frequently associated with asymmetric myopia, which may cause amblyopia.