Management of foveal adhesion of a dexamethasone implant (2015)

The dexamethasone implant (Ozurdex, Allergan, Inc, Irvine, CA, USA) is an FDA-approved intravitreal corticosteroid for the treatment of non-infectious uveitis, macular oedema following retinal vein occlusion, and most recently diabetic macular oedema (DME). Case reports have surfaced regarding occasional malposition of the implant, particularly anterior segment migration (Afshar et al. 2013; Coca-Robinot et al. 2014; Khurana et al. 2014). In this report, we describe a case of postinjection foveal adherence of a dexamethasone implant that was placed during vitrectomy requiring surgical repositioning. A 63-year-old man with DME and proliferative diabetic retinopathy was initially treated with serial intravitreal bevacizumab injections and panretinal laser photocoagulation. Despite therapy, macular oedema persisted with an associated epiretinal membrane (Fig. 1) and was scheduled for a pars plana vitrectomy. He was enrolled in a prospective study examining the use of the dexamethasone implant at the time of vitrectomy for DME (Clinical trial ID: NCT01613716). He underwent vitrectomy with membrane peeling (i.e. ERM and internal limiting membrane) and panretinal photocoagulation. The dexamethasone implant was placed inferotemporally into the posterior chamber with standard technique. A 90% air–fluid exchange was performed, and the implant remained mobile at time of surgical closure. The patient was instructed to avoid supine positioning. On postoperative day 1, 80% air-fill remained and the dexamethasone implant was adherent to the fovea centre. The patient was instructed to maintain upright positioning with intermittent supine positioning to allow for fluid to interact with the implant. Six days following surgery, a 40% air-fill remained and the implant was unchanged (Fig. 1). VA was 20/125, and the patient noted a central linear scotoma. The next day, vitrectomy with implant repositioning was performed. The implant was carefully lifted from the macular surface with a soft-tip cannula and positioned to the mid-periphery (Fig. 1). Intra-operative OCT confirmed removal without underlying gross alterations of the fovea. Prior to leaving the OR, the posterior pole was visualized with the patient upright. The implant gently moved to the inferior vitreous cavity. Strict upright positioning was performed. Postoperatively, the implant remained in optimal position in the inferior vitreous cavity. The pre-existing retinal oedema improved significantly, and the VA improved to 20/20 (Fig. 1). No additional complications were noted with resolution of oedema. Malposition of the dexamethasone implant has been reported in association with silicone oil after complicated retinal detachment repair. The implant migrated to the fovea and remained trapped beneath the silicone oil over a month (Afshar et al. 2013). The implant spontaneously moved inferiorly, but a linear scotoma persisted with a corresponding pigmented ERM. Two cases of intralenticular injection of dexamethasone implant have also been reported (Coca-Robinot et al. 2014). Cataract progression and increased intra-ocular pressure were noted. Recently, Khurana et al. (2014) reported 18 eyes of 15 patients with dexamethasone migration into the anterior chamber. Sixteen of 18 cases developed corneal oedema. In ten cases, the oedema did not spontaneously resolve, and six cases required corneal transplantation despite implant removal, supporting early intervention for implant malposition (Khurana et al. 2014). In our case, intravitreal dexamethasone implant was administered without any complication and the implant was confirmed to be freely mobile upon completing surgery but was firmly adherent to the fovea postoperatively. The muzzle velocity of the impact during introduction has been calculated at 0.8 m/seconds and decreases dramatically over time (Meyer et al. 2012). Factors that may have contributed to adherence include the formation of fibrin following membrane peeling and the air–fluid exchange. Early repositioning was performed with an excellent anatomic and visual outcome. To our knowledge, this is the first report of a dexamethasone implant that is adherent to the macula in a fluid-/air-filled eye.