RVO Stabilizes, but Does Not Improve, With Dexamethasone Implant, Study Says

Intravitreal dexamethasone implants were found to stabilize, but not improve, vision for most patients with retinal vein occlusion (RVO) even though a majority were pretreated and were receiving the steroid injections as a second-line treatment, a new study showed.

Researchers from Germany targeted the effectiveness of treatment of macular edema (ME), the most frequent vision-threatening consequence of RVO. Most patients previously had been treated with anti-vascular endothelial growth factor (anti-VEGF) agents, with a handful having received intravitreal corticosteroids (triamcinolone).

Results from the study, published in Scientific Reports, found treatment with dexamethasone intravitreal implants (marketed as Ozurex) maintained mean [SD] visual acuity (VA) throughout the observation period (about 10 months on average), with a baseline of 66.7 [23.5] letters and measurements at final observation of 64.9 [28.3]. Central retinal thickness (CRT) saw a reduction from 526 [179] μm at baseline to 431 [199] μm. There was a slight increase in mean intraocular pressure (IOP), rising from 14.4 [3.1] mmHg at baseline to 17.1 [6.3] mmHg.

“Considering the fact that most patients (83%) in this study were not treatment-naïve at the time of first DII treatment, the overall VA results are not surprising,” the researchers said. “Mean VA could be stabilized but did not increase significantly. This may, to a large extent, be contributed to the fact that long-standing or frequently recurring edema has a lower potential for VA increase due to either macular ischemia or structural retinal damage or a combination of both. In this light, it is reassuring that almost one-third of the DII treated eyes were considered a treatment success (ie, having fully resolved macular edemas).”

RVO is the second most common retinal vascular disease after diabetic retinopathy. It is estimated that 16.4 million adults worldwide are affected by RVO and conditions that subsequently develop. The cumulative 10-year incidence was 1.6% in the Blue Mountain eye study of patients 49 and older. ME can be treated with intravitreal injection of anti-VEGF agents or corticosteroids, but when edema is chronic, it poses a challenge to clinicians.

The study evaluated a real-life cohort of 99 eyes from 99 patients with ME due to RVO. Patients were treated between 2011 and 2016 at the University Eye Hospital Freiburg, Germany.

Most eyes were not treatment naïve: 61 eyes (62%) had received anti-VEGF injections prior to DII, 6 (6%) eyes had received triamcinolone, and 15 eyes (15%) had received both. Only 17 eyes (17%) received DII as a first-line treatment. Mean duration of follow-up in the study was 312 [310] days. The number of DII treatments ranged from 1 to 10 with a mean of 2.2 [2.1] injections.

Overall, 47 eyes (47%) did not experience the desired effect and either were stopped from further treatment or switched to other treatments.

Main concerns expressed by the authors were increased IOP and cataract formation. The slight increase translated into a similar increase in usage of intraocular pressure-lowering drops. Over 75% did not require any IOP-lowering therapy during the follow-up period, which was up to 3 years. The IOP returned toward baseline values at later time points. The authors speculated the decrease was because those who showed a significant IOP increase after the first injection frequently did not receive another.

Fifty-eight eyes were phakic at initiation of DII treatment, meaning they were at risk of cataracts. Of those, 13 eyes (22%) received cataract surgery during the follow-up period. Cataract surgery (as well as elevated IOP) occurred less frequently during this study than others.

Reference

Wecker T, Grundel B, Grundel M, et al. Real-life medium term follow-up data for intravitreal dexamethasone implant in retinal vein occlusion. Sci Rep. 2021;11(1):8303. doi:10.1038/s41598-021-87467-6