Sporadic Optic Nerve Glioma Case Presenting with Unilateral Proptosis in a Child

INTRODUCTION

Optic nerve gliomas (ONGs) are uncommon tumors arising along the optic nerve pathway and are most frequently classified as pilocytic astrocytomas. These tumors are typically benign and slow-growing, predominantly affecting children aged 1 to 6 years, whereas malignant variants are rare and more commonly seen in adults.¹ ONGs usually involve the pre-chiasmal segment of the optic nerve but may extend posteriorly to the optic chiasm and adjacent intracranial structures if untreated.²

A strong association exists between ONGs and neurofibromatosis type 1 (NF1), with 50–70% of pediatric optic pathway gliomas occurring in patients with NF1.² In such cases, the tumors often have a relatively benign course and may remain asymptomatic or stabilize spontaneously over time. In contrast, sporadic optic nerve gliomas, which occur in the absence of NF1, are less common and tend to present later in childhood or adolescence. These tumors are more likely to exhibit aggressive clinical behavior, manifesting as progressive visual loss, optic disc edema, optic atrophy, and disfiguring proptosis.¹

We report a rare case of sporadic optic nerve glioma in a 12-year-old child presenting with acute unilateral vision loss and proptosis, without association with NF1.³

CASE REPORT

A 12-year-old female child from Bapatla presented to the ophthalmology outpatient department with complaints of sudden diminution of vision in the left eye (LE) associated with headache for the past 7 days. The child was apparently normal 10 days prior to presentation and suddenly developed LE visual loss while playing. There was no history of ocular trauma or systemic illness. The patient’s mother served as a reliable informant.

On examination, best-corrected visual acuity was 6/6 in the right eye (RE) and counting fingers at 2 m in the LE. Proptosis of the LE was noted on inspection. Slit-lamp examination revealed a normal anterior segment in the RE, while the LE showed mild bulbar conjunctival congestion with an inferior conjunctival nevus. A grade 3 relative afferent pupillary defect (RAPD) was present in the LE.⁴

Further evaluation showed a complete color vision defect in the LE. Confrontation visual fields were full in the RE and restricted to the central 5 degrees in the LE. Extraocular movements were full, free, and painless in all gazes. Inspection using the worm’s view and Naffziger’s view confirmed LE proptosis [Figure 1a and b]. Hertel’s exophthalmometry measured 18 mm in the RE and 21 mm in the LE, with a base of 92 mm. On palpation, the orbital mass was non-reducible and non-compressible, with a positive retropulsion test. No bruit was heard on auscultation.

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Figure 1a:

Nafziger’s view showing left eye proptosis.

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Figure 1b:

Worm’s view showing left eye proptosis.

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Fundus examination of the RE was normal. The LE showed a hyperemic optic disc with blurred margins, suggestive of disc enema, along with dilated and tortuous retinal vessels and an obliterated cup–disc ratio, while the foveal reflex was preserved [Figure 2].⁵

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Figure 2:

(a and b) left eye optic disc edema.

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Radiological findings

Orbital imaging revealed a fusiform enlargement of the left optic nerve measuring 23 × 18 mm, resulting in proptosis. The lesion extended posteriorly into the optic canal, causing widening of the left optic canal (7.3 mm) compared to the RE (4 mm). These findings were suggestive of optic nerve glioma [Figure 3].⁶

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Figure 3:

(a) CT orbit showing a fusiform enlargement of the left optic nerve (b) MRI confirming optic nerve glioma.

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DISCUSSION

This case represents an unusual presentation of sporadic optic nerve glioma in an older child without NF1, highlighting the importance of early recognition in pediatric patients presenting with unilateral proptosis and vision loss.^3,7 The differential diagnoses include optic neuritis, autosomal dominant optic atrophy, and other intracranial or orbital neoplasms.⁵

MRI remains the gold standard for diagnosing ONGs due to its superior soft tissue contrast and ability to delineate tumor extent. At the same time, CT is useful for detecting enlargement of the optic canal and bony changes.⁶

Management of ONGs depends on tumor progression, visual function, and NF1 status. In sporadic cases with progressive disease, chemotherapy is the preferred first-line treatment. Surgical intervention is reserved for cases with severe proptosis or intracranial extension, though complete excision is often avoided due to the risk of significant visual and neurological impairment.^7,8

CONCLUSION

Early diagnosis is crucial, as delayed recognition may result in irreversible visual impairment and extension of the tumor to the optic canal, chiasm, or intracranial structures. A comprehensive ophthalmic evaluation, combined with prompt neuroimaging, is essential for early detection and appropriate management.

This case emphasizes the need for a high index of suspicion for optic nerve glioma in children presenting with unilateral proptosis and vision loss, even in the absence of NF1. Early diagnosis and a multidisciplinary approach are crucial for appropriate management and favorable outcomes.