Urrets-Zavalia syndrome (fixed and dilated pupil following penetrating keratoplasty for keratoconus) and its variants

Urrets-Zavalia Syndrome (UZS) was described 50 years ago as the appearance of a fixed and dilated pupil following penetrating keratoplasty for keratoconus in patients receiving atropine. The mechanism of UZS has still not been fully determined, but an acute increase in intraocular pressure and ischemia of the iris most probably play a major role. Fixed and dilated pupils also occur in association with other ophthalmic surgeries, such as lamellar keratoplasties, cataract surgery, and glaucoma procedures. Some have questioned the existence of this syndrome, as well as the linkage to keratoconus and use of mydriatics. We review the pathophysiology, etiology, and clinical presentation of fixed and dilated pupils following ophthalmic procedures.