Objective:

To describe a rare case of pembrolizumab-induced bilateral optic neuritis with panuveitis and provide a comprehensive review of literature to highlight key diagnostic and management principles for this vision-threatening immune-related adverse event (irAE).

Background:

While immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy, they can induce a wide spectrum of irAEs. Although ocular irAEs are rare (<1%), they include serious, vision-threatening complications like optic neuritis. This specific condition poses a distinct diagnostic challenge, as its presentation is often atypical, and few cases have been reported. Unlike classic demyelinating optic neuritis, it usually involves bilateral, painless vision loss, sometimes with preserved color vision. Recognizing this rare complication is critical, as prompt immunosuppressive therapy can prevent permanent blindness.

Design/Methods:

N/A

Results:

A 63-year-old man with metastatic non-small cell lung cancer developed progressive bilateral painless vision loss after 15 cycles of pembrolizumab. Ophthalmic examination revealed bilateral optic disc edema and panuveitis. Extensive workup including MRI of the orbits, cerebrospinal fluid analysis, infectious and autoimmune studies was unrevealing, supporting a diagnosis of pembrolizumab-associated optic neuritis. Following discontinuation of pembrolizumab and administration of high-dose intravenous corticosteroids, his vision markedly improved from light perception to 20/30 in both eyes. Review of published cases suggests that ICI-associated optic neuritis typically presents bilaterally after multiple treatment cycles, often with unremarkable imaging and laboratory findings, and generally responds favorably to corticosteroids, though some cases required escalation to plasmapheresis or additional immunomodulators. Outcomes varied, with partial to full recovery in most, although some cases resulted in permanent visual loss.

Conclusions: