Dexamethasone improves visual outcomes in BRVO-associated macular oedema
Early intravitreal implantation of the corticosteroid dexamethasone at an interval of ≥4 months provided rapid and significant improvement in best-corrected visual acuity (BCVA) and central retinal thickness (CRT) in patients with macular oedema following branch retinal vein occlusion (BRVO), according to the COBALT* study.
“[A]s early as week 1 … approximately 70 percent of the maximum improvement in BCVA and reduction in CRT was observed. This is a novel finding,” said the researchers, noting the mean improvements in BCVA of 12.8 letters and CRT of 173.7 μm (p<0.0001 for both) from baseline measurements of 51.9 letters and 505.1 μm, respectively.
BCVA improvement and CRT reduction persisted at 6 (18.6 letters and 246.8 μm, respectively; p<0.0001 for both) and 12 months (15.3 letters and 196.9 μm, respectively; p<0.0001 for both). Both timepoints also saw a gain of ≥15 letters (≥3 ETDRS** lines) in 65 percent and 56 percent of participants, respectively. [Ophthalmologica 2018;240:81-89]
Thirty-two and 49 percent of individuals received one and three injections, respectively, over 12 months with a mean interval of 20.0 weeks. Patients who required three injections had a significantly thicker CRT (644.7 vs 506.5 μm; p<0.016) and larger macular nonperfusion area (26.7 percent vs 12.9 percent) at baseline compared with those who only required one injection.
“[T]hese results suggest that patients with BRVO whose CRT is >600 μm and who have significant macular nonperfusion should be reviewed more frequently, since these patients may require dexamethasone implants on a 4-monthly basis,” they said.
The most common adverse event (AE) was increased intraocular pressure (IOP; 35 percent) which was well-managed with IOP-lowering agents. Other common AEs were cataract and posterior vitreous detachment (16 percent and 6 percent, respectively).
The results were found after evaluating 71 individuals (mean age 57.5 years, 54 percent male) with treatment-naïve BRVO-associated macular oedema involving the centre of the fovea for <3 months with visual acuity loss due to macular oedema, and CRT of ≥340 μm. Initial dexamethasone 0.7 mg intravitreal implant was administered on day 0. Retreatment was allowed ≥4 months from the last injection.
The early treatment outcomes in the current study appear to outdo those found in the GENEVA*** trial, which showed improvement with dexamethasone only on day 30. [Ophthalmology 2010;117:1134-1146] Moreover, retreatment interval in GENEVA was at least 6 months as opposed to the current study interval of 4 months, and only 16 percent of GENEVA participants had symptoms of macular oedema for <90 days as opposed to the 100-percent rate in COBALT.
The proportion of eyes exhibiting worsening further underlined the significance of early dexamethasone treatment and retreatment at optimal intervals. The current findings reveal a worsening of ≥15 letters in 2 and 5 percent of the study population at months 6 and 12, which were lower than those found in GENEVA at month 6 (6 percent).
Delaying treatment for BRVO-associated macular oedema compromises prognosis and may result in vision loss, [Curr Eye Res 2008;33:111-131] with each 1-month increase in duration associated with a reduced likelihood of achieving BCVA improvement or CRT reduction. [Ophthalmology 2012;119:1190-1198] Conversely, early treatment is associated with better visual outcomes especially if treatment is initiated within 2 weeks after onset. [Jpn J Ophthalmol 2014;58:146-154]
“[Taken together,] these factors may have contributed to better efficacy results observed in our study, which also reflects real-world practice patterns,” said the researchers. “Compared with other studies … our results were better, possibly related to multiple factors, including the duration of macular oedema at baseline and retreatment intervals.”
Nonetheless, given the lack of a control group in the current trial, researchers called for further studies with sham or active controls to facilitate a more comprehensive analysis of the efficacy and safety of dexamethasone implants.