Abstract Introduction: Zoledronic acid is a potent bisphosphonate used to manage osteoporosis, Paget’s disease, hypercalcemia of malignancy, multiple myeloma, and metastatic bone disease. While generally well tolerated, bisphosphonates can have ocular side effects, including orbital inflammation and optic neuritis. Optic perineuritis (OPN), an inflammation of the optic nerve sheath, is an underreported zoledronate side effect. Case report: We describe a 75-year-old male with osteoporosis who developed left eye pain, ptosis, swelling, diplopia, and headache after a 4 mg zoledronate infusion. Examination showed left eye periorbital edema, erythema, ptosis, conjunctival injection, proptosis, and severe tenderness. Imaging revealed left orbital fat stranding and bilateral optic nerve sheath enhancement. Infectious and inflammatory work-ups were negative. Diagnosed with zoledronate-associated orbital inflammation, he was treated with high-dose intravenous methylprednisolone, resulting in significant improvement. Zoledronate was discontinued, and no symptoms recurred over a year. Ocular inflammation is a rare adverse effect of bisphosphonates, with neuro-ophthalmic complications being even rarer. Conclusion: This is the first reported case of OPN linked to zoledronate. Prompt recognition and treatment of this rare adverse effect are crucial to prevent permanent visual impairment.
Keywords: optic perineuritis; orbital inflammation; zoledronate; zoledronic acid