A positive response to a previous dexamethasone implant predicts more significant anatomic improvement after switching to a fluocinolone acetonide (FAc) implant, according to findings published in Eye.

Anti-vascular endothelial growth factor (VEGF) agents are a first-line treatment approach for diabetic macular edema (DME). If patients don’t respond to anti-VEGF treatment or have systemic contraindications to antiangiogenic treatment, intravitreal corticosteroids are recommended.

Two steroidal drug-delivery systems are approved for DME. The dexamethasone 700 μg bioerodable implant releases a high dose in the first 2 months, followed by a lower-dose for the next 4 months. The FAc 0.19 mg nonbioerodable implant, on the other hand, delivers a low-level, steady dose for 36 months. In Europe, the FAc implant is approved for use only if other agents were unsuccessful.

The researchers conducted a retrospective cohort study to determine if the visual and anatomic response to the first dexamethasone implant can predict the response to the FAc implant in patients with DME. Functional and morphologic response to the dexamethasone implant was measured via best-corrected visual acuity (BCVA) and central macular thickness (CMT) changes after the first DEX. Steroid response was defined as intraocular pressure (IOP) elevation of 5 mm Hg or greater or IOP readings of 21 mm Hg or lower after any previous dexamethasone exposure.


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Investigators found that the morphologic changes observed after FAc were predicted by looking back to the first injection of the dexamethasone intravitreal implant. Specifically, patients with a greater macular thinning after dexamethasone had a more significant CMT reduction in the first year post-FAc injection. Conversely, eyes with an inadequate morphologic response to the first dexamethasone implant saw an insignificant change in the CMT values after switching to FAc, according to the findings.

The team examined 44 eyes of 33 patients. Patients were shifted to FAc after approximately 4.6 dexamethasone implant injections. Overall, BCVA and CMT improved during the first 12 months after switching to FAc (P =.04 and P <.001, respectively). Only eyes with a good morphologic response to dexamethasone had a significant CMT reduction after FAc (P <.001). The team noted no significant relationship between BCVA improvement after dexamethasone and after FAc. Elevated IOP occurred in 9 eyes (20%) following the dexamethasone implant. These eyes carried a 20-fold increased risk of having an IOP rise after FAc (P < 0.001), with a non-linear relationship between the IOP increases after dexamethasone and the one after FAc.

Investigators concluded that eyes with steroid-induced IOP elevation after dexamethasone also have an increased risk of elevated IOP after FAc. 

This study had several limitations, including the short follow-up and analyzing outcomes after only the first injection of the dexamethasone implant. In addition, the study didn’t include information about the perfusion state of the macula and its relationship to the response to the FAc implant. Further, although useful for this task, optical coherence tomography angiography is not the standard of care for following DME. Lastly, the study didn’t include a control group, making it potentially vulnerable to regression to the mean.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Cicinelli MV, Rosenblatt A, Grosso D, et al. The outcome of fluocinolone acetonide intravitreal implant is predicted by the response to dexamethasone implant in diabetic macular edema. Eye. January 21, 2021. doi:10.1038/s41433-020-01373-1