When Uveitis and Hypotony Meets Bilateral Iris Retraction Syndrome: A Rare but Serious Complication of Nivolumab Treatment.

Introduction: Iris retraction syndrome (IRS) is a rare clinical condition characterized by a backbowing of the iris positioned on the lens with a complete pupillary block. Immune checkpoint inhibitors (ICIs) are a new class of immunomodulating agents used in cancer therapy, and although they have high response rates, ophthalmic-related side effects have been reported. We report a rare case of bilateral IRS with hypotony after therapy with nivolumab. Case Presentation: We present a case of bilateral IRS with hypotony, 3 mm Hg OD and 5 mm Hg OS, after therapy with nivolumab. The patient presented with decreased vision, corneal edema, keratic precipitates, deep anterior chamber with posterior synechiae, and hypotony maculopathy. Anterior segment OCT revealed a sharp posterior displacement of the iridolenticular diaphragm consistent with IRS. Discontinuation of nivolumab until ocular improvement was suggested, following oncologic consultation. Four months later, the patient exhibited iris bombé with angle closure and increased IOP. This was managed with phacoemulsification and concomitant surgical iridectomy. One month after surgery, the patient's IOP had returned to physiologic values, and the iris configuration had returned to normal. Conclusion: The exact mechanism of IRS remains unclear, but it is suggested that an aqueous imbalance, in conjunction with uveitis and hypotony, creates an anterio-posterior movement of the iridolenticular diaphragm when the pupillary block is present. Our case highlights the importance of monitoring patients receiving ICIs for ophthalmic adverse effects and prompt management to prevent permanent visual damage. In conclusion, this is the first reported case of IRS after therapy with ICIs. Further research is needed to fully understand the exact mechanism by which it is induced.