Intravitreal injection of Ozurdex (Allergan Inc) is one of the effective treatment methods for macular edema caused by diabetic retinopathy, retinal vein occlusion, and uveitis. This intravitreal implant has a biodegradable property to provide a sustained release of preserved-free dexamethasone to the vitreous and retina. It can be inserted into vitreous cavity through a minimally invasive pars plana puncture, facilitated by a specialized applicator system. Recently, there were several cases of misplacement or migration of implants during or after intravitreal injections. Given the possibility of complications including cataract, corneal edema, and retinal damage, it is crucial to exercise caution regarding implant mislocalization. In this report, we present a previously undocumented case where dexamethasone implant was adherent to surface of fovea in a nonvitrectomized eye, highlighting the significance of this occurrence. Written informed consent for publication of the research details and clinical images was obtained from the patient.

Four years ago, an 83-year-old woman with diabetes, hypertension, and chronic kidney disease was diagnosed with hemi-central retinal vein occlusion in her left eye. She received eight intravitreal bevacizumab injections, but macular edema was poorly controlled. Subsequently, she underwent 11 injections of dexamethasone implant (Ozurdex) at 3- to 4-month intervals. She also underwent laser treatment for diabetic microaneurysms and ischemic retina. Over the past 2 years, her best-corrected visual acuity (BCVA) has remained without changes, with 20 / 20 in the right eye and counting fingers in the left eye. Prior to 12th injection of dexamethasone implant, fundus findings and image of optical coherence tomography (OCT) of the left eye were as follows (Fig. 1A, 1B). The dexamethasone implant was injected into inferotemporal quadrant of eyeball, approximately 3.5 mm from limbus. Three months after 12th injection, OCT showed dexamethasone implant was adherent to fovea (Fig. 1C, 1D). Although the implant was positioned in front of fovea, she did not complain of any new visual symptoms or discomfort. Furthermore, no additional abnormalities, which could be attributed to the implant, were observed in fundus examination and OCT imaging. She denied any history of ocular trauma or excessive movement that could explain abnormal positioning of implant. Despite maintaining a lateral sleeping position and sitting posture during the day for 3 weeks, position of the implant remained unchanged (Fig. 1E, 1F).

There were few previous case reports where dexamethasone implant was attached to macula. Kim et al. [1] presented a case where dexamethasone implant persisted on perifoveal macula in a vitrectomized eye that went through several bevacizumab injections, and did not result in any significant complications. Afshar and Loh [2] reported a case where implant stayed at perifoveal macula, in between silicone oil and retinal surface. Their patient complained of scotoma related to the implant at 1 month, and pigmented epiretinal membrane corresponding to implant adherent site occurred at 2 months. Kim et al. [3] reported a case of dexamethasone implant on fovea in a vitrectomized eye, considering it to be a complication requiring surgical management. After surgical intervention, no specific damage related to the implant was observed.

We presented a case of a nonvitrectomized eye, whereas previous studies presented cases of vitrectomized eyes. Implant placed at fovea caused visual symptoms in the case where patient’s BCVA was better than 20 / 80, but in our case, patient could only count fingers which might explain why she had no visual complaints.

Although the exact mechanism of implant mislocalization remains elusive, previous studies suggested poor patient cooperation, surgeon’s inexperience, a too-acute injection angle, and use of less refined drug delivery system applicator as the reason of misplacement. However, our case showed limited relevance to the aforementioned factors. Instead, vitreous liquefaction associated with aging process had significant implications for drug delivery and degradation [4]. Kim et al. [5] reported that patients with persistent remnants had significantly higher numbers of previous intravitreal dexamethasone and triamcinolone acetonide injections than patients without remnant persistence. We speculate that vitreous liquefaction and multiple injections might have contributed to the mislocalization of implant in our case.

To the best of our knowledge, this is the first case report demonstrating misplacement at fovea following intravitreal injection of dexamethasone implant in a non-vitrectomized eye. No complications related to the mislocalized implant was observed on funduscopic examination and OCT image. Therefore, we suggest that it is sufficient to observe dexamethasone implant adherent to fovea without surgical intervention. Moreover, additional intravitreal Ozurdex injections can be safely performed.