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Editor,—A fixed and dilated pupil is an uncommon postoperative complication first described by Urrets-Zavalia following penetrating keratoplasty for keratoconus.1 We report the same problem occurring in two patients after uncomplicated trabeculectomy. To the best of our knowledge, such cases have not been previously described in the literature.
A 38 year old woman with bilateral advanced glaucoma was referred for further management of her condition. Her ophthalmic history included surgery to her left squint as a child and left amblyopia. She was otherwise fit and well and took no systemic medication.
On examination her best corrected visual acuities were 6/6 in the right eye and 6/36 in the left with a left relative afferent pupillary defect. Her anterior segments were normal and her intraocular pressure (IOP) was 19 mm Hg bilaterally on timoptol twice daily. Gonioscopy revealed open angles and funduscopy showed end stage optic disc cupping in both eyes. Despite attempts to lower her IOPs further, they remained uncontrolled on maximal tolerated topical treatment.
A left then right uneventful trabeculectomy with peroperative 5-FU was carried out. Postoperatively, her topical medication was dexamethasone (Maxidex, Alcon) and chloramphenicol. Both IOPs were well controlled and she maintained the same preoperative visual acuity. Following surgery the patient noticed her right pupil was larger than the left.
On examination her right pupil was dilated with no direct or consensual response to light and no constriction to accommodation. There was also no reaction to either 0.125% or 4% pilocarpine drops. The left pupil had normal characteristics. Iris fluorescein angiography revealed delayed filling of the iris capillary plexus with large areas of non-perfusion on the right (Fig 1A). The left iris angiogram was normal (Fig 1B).
A 60 year old Turkish woman was referred with a high IOP in her right eye. She had no ophthalmic history of note. Her medical history was unremarkable and she took no medication.
On examination her best corrected visual acuities were 6/9 in the right eye and 6/6 in the left. Her anterior segments were normal and her IOPs were 40 mm Hg in the right eye and 15 in the left. Initial medical treatment failed to control her IOP and a right trabeculectomy was carried out 2 months after presentation. Since the operation her right IOP has been controlled but her right pupil has remained fixed and dilated (Fig 2A). On examination of her pupils, there was no right direct or consensual response to light or constriction to accommodation. There was also no reaction to either 0.125% or 4% pilocarpine drops. The left pupil was normal (Fig 2B). Iris angiography was not possible in this case owing to her darkly pigmented irides.
To our knowledge these are the first cases of Urrets-Zavalia syndrome to be reported after trabeculectomy. The clinical features of this syndrome following penetrating keratoplasty for various conditions are well established1-5 but the pathophysiological mechanisms responsible for the mydriasis remain uncertain. Iris ischaemia secondary to postoperative rise in intraocular pressure has been suggested as the likely aetiology6 7 with possible immunological,4 neurological,8-10 and structural iris6 changes playing a role. We have discounted other possible causes of an internal ophthalmoplegia in our cases by ruling out Adie's pupil as there was no response to accommodation or to 0.125% pilocarpine. There was also no history of mydriatic use preoperatively or postoperatively and the pupil did not react to 4% pilocarpine. In addition, both patients had full extraocular movements with no ptosis and no other associated neurological signs suggestive of a third nerve palsy. There was no peroperative use of viscoelastic substances and both patients had minimal inflammation postoperatively. The angiography findings confirm the iris ischaemia as the most probable cause of the unilateral dilated pupil. Peripheral iridectomies performed as part of the trabeculectomy did not protect against this syndrome as is believed by some authors.6 11 12 It is interesting to note that the syndrome occurred unilaterally in case 1 despite bilateral surgery. A similar finding is also reported by Saraux et al following penetrating keratoplasty.4