Diabetic Macular Edema: Dexamethasone Implant May Improve Vision

Troy Brown, RN

September 22, 2016

A dexamethasone implant improved the physiological morphology of the outer retinal layers in patients with recalcitrant diabetic macular edema (DME) associated with proliferative diabetic retinopathy, a new case series has found.

"Our results showed that dexamethasone implant has a positive outcome in terms of visual acuity improvement and [central macular thickness (CMT)] reduction, at the 6-month and at the 12-month observation, with a retreatment interval under 6 months," the researchers write.

Pierluigi Iacono, MD, from the G.B. Bietti Foundation for Study and Research in Ophthalmology, Istituto di Ricovero e Cura a Carattere Scientifico, Rome, Italy, and colleagues report their findings in an article published online September 13 in the British Journal of Ophthalmology.

The prospective, interventional case series included 13 consecutive patients (18 eyes) with recalcitrant center-involving DME associated with proliferative diabetic retinopathy, CMT 300 mm or higher, and previous platelet-rich plasma therapy, focal/grid laser treatment, and anti-vascular endothelial growth factor injection.

The researchers conducted a complete ophthalmological examination that included best-corrected visual acuity (BCVA) assessment, slit-lamp examination, applanation tonometry, fluorescein angiography, and spectral domain optical coherence tomography.

The patients underwent insertion of a 0.7-mg dexamethasone implant (Ozurdex, Allergan) into the vitreous cavity through the pars plana with a customized, single-use 22-gauge applicator in the operating room. Patients received a topical ophthalmic antibiotic for 4 days and were observed for adverse effects for the study duration. They underwent a bimonthly ophthalmological examination and received retreatments if necessary for persistent or recurrent DME from the fourth month on during the 12-month follow-up.

BCVA improved significantly from 0.99 ± 0.31 standard deviation (SD) LogMAR (logarithm of the minimum angle of resolution; Snellen equivalent: 20/196) at baseline to 0.83 ± 0.27 SD LogMAR (Snellen equivalent: 20/136; P = .004) at the 6-month examination, and to 0.77 ± 0.25 SD LogMAR (Snellen equivalent: 20/117; P < .001) at the 12-month examination.

CMT fell from 510 ± 169 SD mm at baseline to 480 ± 190 SD mm (P = .46) at 6 months and to 423 ± 171 SD mm (P = .018) at 12 months.

Secondary outcomes also improved, the researchers report. At baseline, external limiting membrane was absent in 38.9% of cases and disrupted in 61.1% of cases compared with being absent in 22.2% of cases, disrupted in 55.6%, and present in 22.2% (P = .02) at 12 months. Ellipsoid zone (EZ) was absent in 22.2% and disrupted in 77.8% of cases at baseline compared with absent in 5.6%, disrupted in 83.3%, and present in 11.1% of cases (P = .025) at 12 months. Retinal pigment epithelium was disrupted in 72.2% of cases and present in 27.8% at baseline compared with disrupted in 33.3% and present in 66.7% of eyes (P = .008) at 12 months.

"With regard to EZ, the eyes showing absent EZ at baseline did not reveal any BCVA improvement at the end of the follow-up," the authors write.

"On the contrary, eyes with disrupted or present EZ at baseline significantly improved their BCVA (p=0.001). The [retinal pigment epithelium] layer was classified as present or disrupted in all the eyes and BCVA had significantly improved by the end of the 12 months," they continue.

"So, judging by our results, the integrity of EZ plays an important role as a prognostic factor and a combined analysis of EZ and ELM could provide interesting prognostic information," they conclude.

Study limitations include that it was uncontrolled and included a small study population. In addition, the study did not perform subclassification accounting for patients with type 1 and type 2 diabetes.

"However, the survey provides fresh insights into a topic that is rarely explored but is nevertheless of great interest, contributing to the evaluation of the functional and morphological efficacy of several intravitreal dexamethasone implants for recalcitrant macular oedema," the authors write.

One author reports being an advisory board member for Allergan, Novartis Pharmaceuticals Corporation, Farmila-Thea, Bayer Schering Pharma, Pfizer, Alcon, Bausch and Lomb, Genentech, Alimera Sciences, sanofi aventis, and Thrombogenics. One author is a consultant for Novartis Pharmaceutical Corporation (Switzerland), and one author is consultant for Bayer. The remaining author has disclosed no relevant financial relationships.

Br J Ophthalmol. Published online September 13, 2016. Abstract

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