Risk factors for and management of anterior chamber intravitreal dexamethasone implant migration

BACKGROUND: This study aimed to investigate the incidence of and risk factors for the anterior chamber migration of an intravitreal dexamethasone implant (Ozurdex®). METHODS: A retrospective review of 640 consecutive intravitreal dexamethasone implant injections was conducted from February 2011 through February 2018 at the University Eye Hospital in Tübingen, Germany. Those patients who experienced anterior chamber dexamethasone implant migrations were identified, as well as the reasons for the anterior chamber migration. The surgical histories were obtained and comprehensive ophthalmic examinations were conducted for all of the eyes. Cross-tabulations, chi-squared tests, and Fisher’s exact tests were used to assess the influences of different factors on the anterior chamber implant migrations. RESULTS: Overall, 4 eyes of four patients (0.63%) showed anterior chamber implant migrations. All four of the eyes were pseudophakic, and they had undergone prior vitrectomies. Three eyes had sclerally-fixated intraocular lenses, and one eye had a posterior chamber intraocular lens in the capsular bag, with a capsular tension ring due to partial zonular dehiscence. When comparing the vitrectomized eyes with reduced zonular/capsular bag complex integrity to the vitrectomized pseudophakic eyes with intact zonular/capsular bags, the former were significantly associated with an increased risk of anterior chamber implant migration (P = 0.008). The vitrectomized pseudophakic eyes, in contrast to the nonvitrectomized pseudophakic eyes, were significantly associated with an increased risk of anterior chamber implant migration (P = 0.009). CONCLUSIONS: The anterior chamber migration of an intravitreal dexamethasone implant is a serious complication. To minimize the risk of permanent corneal edema, immediate removal of the implant with a 20-gauge alligator forceps over a 2.75-mm long clear corneal tunnel is important. Those patients with insufficient zonular support, defects, or missing posterior capsular membranes and vitrectomy histories present a high risk of anterior chamber dexamethasone implant migration.