Bilateral retrobulbar optic neuropathy as the only sign of zoledronic acid toxicity.

Introduction: Bisphosphonates may rarely cause ocular adverse effects and retrobulbar optic neuropathy (RON) secondary to zoledronic acid is very rare.

Case Report: A 67-year-old man was referred because of progressive and painless decrease vision in the left eye. He had been treated with 7 cycles of zoledronic acid infusions because of metastatic prostate cancer.