The Ozurdex implant (Allergan, Dublin, Ireland) offers sustained-release dexamethasone and has been used to effectively treat various vitreoretinal diseases including macular edema associated with retinal vein occlusion, non-infectious uveitis, and diabetic macular edema. Although the sustained delivery of dexamethasone has been a valuable asset to the arsenal of retinal medicine, shortly after becoming available, a few reports of the implant migrating into the anterior chamber began to emerge. This can lead to potentially complicated corneal edema with permanent damage to the corneal endothelium, decreased vision and requires immediate removal.
If implant migration has occurred, moving or removing the rogue implant may further complicate the changes that occur in the implant over time. Attempts to grasp the implant in an effort to surgically remove or reposition, can lead to its fracture, and aspiration could cause dispersion of the material. Some clinicians have tried to carefully push the implant back into vitreous, but the likelihood of it returning to the anterior chamber is high.
A recent publication in Graefes Archives of Clinical and Experimental Ophthalmology, describes the clinical course, and individualized management approaches of patients with migration of a dexamethasone implant into the anterior chamber.
They reviewed a total of 924 intravitreal dexamethasone injections and identified four cases in which anterior migration of the implant occurred. In all four cases, the eyes were pseudophakic, one with a PC-IOL in a post-YAG laser capsulotomy state, two eyes with a sulcus IOL, and one eye with an iris-fixated retropupillary IOL. All the cases had a prior vitrectomy with no posterior lens capsule and had previous, uneventful Ozurdex injections. Two of the eyes required surgical removal of the implants. Repositioning of the implant back into the vitreous cavity was successful in the two other cases. One of the study authors, Dr. Min Kim, M.D., from the Gangnam Severance Hospital and Yonsei University College of Medicine in South Korea, provided some insight: “Repositioning the implant may be considered as an option in cases involving the first episode with no significant corneal endothelial decompensation.”
Why are these implants migrating in the first place, and can we predict which ones will move? The authors suggest that previously vitrectomized eyes may facilitate the migration, because they are missing the scaffold that holds the implants in place. Additionally, they point out that because the vitreous cavity is filled with aqueous fluid after vitrectomy, any change in fluid dynamics could contribute to the movement of the implant.
The paper concluded that when the differences within and across cases was carefully considered, neither repositioning nor removal was a strong predictor of treatment outcomes. They advise clinicians to carefully consider both the advantages and disadvantages of repositioning the implant in the eye. As well, they note that not all patients need to have the dislocated implants removed, and repositioning them back into the vitreous cavity might be the first option to consider, in the absence of severe corneal decompensation.
“Considering potential anterior segment complications and the loss
of drug effectiveness together, our results suggest that instead of always removing the implants immediately, an individualized approach is recommended to obtain the best treatment outcomes and to minimize the risk of corneal complications,” Dr. Kim explained.
Reference:
Kang H, Lee MW, Byeon SH, et al. The clinical outcomes of surgical management of anterior chamber migration of a dexamethasone implant (Ozurdex®). Graefes Arch Clin Exp Ophthalmol. 2017; doi: 10.1007/s00417-017-3705-y. [Epub ahead of print]
