SUN-793 - A Rare Case of Zoledronic Acid-Associated Orbital Inflammation and Optic Perineuritis

Background: Zoledronic acid is widely used for osteoporosis and can be associated with acute-phase reactions such as fever and myalgias. Rarely, bisphosphonates have been implicated in orbital inflammation (OI). Optic perineuritis following zoledronic acid infusion is exceedingly uncommon, with only isolated cases reported.


Case: A 72-year-old woman with severe osteoporosis (lowest DEXA T-score −3.6) presented to the emergency department with acute painful right eye swelling, chemosis, mechanical ptosis, and subjective fever one day after her first zoledronic acid infusion. She had no prior exposure to oral bisphosphonates due to gastroesophageal reflux disease and had a remote history of ankle fracture. Visual acuity and intraocular pressures were normal. Slit-lamp examination demonstrated diffuse scleral injection without funduscopic pallor or edema. Laboratory evaluation revealed an erythrocyte sedimentation rate of 111 mm/hr; thyroid peroxidase antibodies were positive, while thyroid-stimulating immunoglobulin, IgG subclasses, ANA, and ANCA were negative. MRI of the orbits with and without contrast showed enhancement and inflammation of the right globe extending along the optic nerve, lacrimal gland, and adjacent retrobulbar tissues. Neuro-ophthalmology diagnosed optic perineuritis with orbital inflammation secondary to zoledronic acid. She was treated with intravenous methylprednisolone 1 g daily for three days, followed by an oral prednisone taper starting at 60 mg over three months, resulting in complete resolution of eye pain and diplopia.

Discussion: Bisphosphonate-associated orbital inflammation has been reported in approximately 68 cases, most commonly with pamidronate and zoledronic acid. Optic nerve involvement is exceptionally rare. To our knowledge, this represents the second reported case of zoledronic acid–associated optic perineuritis. Unlike the only other reported case of bisphosphonate-associated optic neuritis, which followed multiple infusions with incomplete recovery, our patient presented after a single infusion and experienced complete resolution with timely steroid therapy and cessation of treatment. Although bisphosphonate rechallenge has been successful in select cases, at least one reported case describes recurrence of orbital inflammation following rechallenge, highlighting the high potential risk of re-exposure.

Conclusion:
Orbital inflammation with optic perineuritis is a rare but serious adverse effect of bisphosphonate therapy. Early recognition, cessation of the offending agent, and timely corticosteroid administration are associated with favorable outcomes. Given one report of recurrence of OI following bisphosphonate rechallenge, alternative osteoporosis therapies should be considered, though optimal management strategies after this adverse event remain undefined.

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