To seek for mechanisms to prevent fixed dilated pupil including Urrets-Zavalia syndrome after intraocular surgery by analyzing and classifying the causes of such cases.

Medical records and anterior segment photographic images of patients with fixed dilated pupil who underwent penetrating keratoplasty, lamellar keratoplasty, or cataract surgery were analyzed in a retrospective manner from April, 1984 to February, 2014.

Among 15 cases of postoperative fixed dilated pupil, 8 eyes of keratoconus eyes had received penetrating keratoplasty done and 7 eyes with ocular disorders other than keratoconus underwent intraocular surgeries. In cases 1 and case 2, which received penetrating keratoplasty for keratoconus, dilated pupil with regular pupil border, iris atrophy, and secondary glaucoma occurred; these cases were classified as group 1 and diagnosed as Urrets-Zavalia syndrome. Cases from 3 to 8 which also received penetrating keratoplasties due to keratoconus, irregularly dilated pupil, severe iris atrophy, posterior synechiae after moderate to severe inflammation in the anterior chamber, and fibrotic membrane on the anterior capsule occurred; these cases were classified as group 2. Finally, cases 9 to 15, which had mild inflammation, no fibrotic membrane, and regularly fixed dilated pupil after receiving other intraocular surgeries were classified as group 3.

Differences exist between definite Urrets-Zavalia syndrome and postoperative fixed dilated pupil with regards to regularity of pupillary margin, degree of iris atrophy, posterior synechiae, fibrotic membrane, and posterior subcapsular opacity. Therefore, a new classification of fixed dilated pupil after intraocular surgery which addresses these characteristics is required and various trials to prevent the adverse postoperative complications of fixed dilated pupil should be performed. Preventive measures may include careful control of intraocular pressure, restricting atropine use, completely removing of viscoelastics, and minimal air or gas injection.