Urrets-Zavalia Syndrome After Posterior Chamber Phakic Intraocular Lens Implantation: An Unusual Complication

Dear Editor, Urrets-Zavalia syndrome (UZS), also known as Castroviejo syndrome, is characterized by a fixed dilated pupil and is a recognized complication of various anterior segment surgeries, including cataract surgery, deep anterior lamellar keratoplasty, Descemet stripping automated endothelial keratoplasty, trabeculectomy, iridoplasty, goniotomy, C3F8 injection into the anterior chamber (AC), and phakic intraocular lens (P-IOL) implantation. 1,2The reported incidence in the published literature ranges from 0% to 17.7%, depending on the type of surgery performed and numerous intraoperative and postoperative factors. 1 The pathophysiology of UZS involves iris ischemia causing sphincter muscle atrophy or damage to the radial parasympathetic fibers that innervate the pupil constrictor muscles.Neuronal injury can result from direct trauma or alteration in the acetylcholine mechanism leading to parasympathetic dysfunction.Atrophy of the iris sphincter muscle may be due to surgical injury, use of mydriatic agents,