ME treatment benefits according to duration of BRVO

Macular oedema (ME) is widely known to be a common cause of visual impairment in patients suffering from branch retinal vein occlusion (BRVO).¹ This complication can be treated using intravitreal anti-VEGF agents and steroids; however, the impact of oedema duration on efficacy of the different treatments is an innovative slant that had not been investigated until recently.²

Time-dependent changes

The study consisted of 65 BRVO patients in total, who were separated into two subgroups, early (≤4 months after onset of BRVO) and late (>4 months after onset of BRVO) treatment. Within these groups the patients were divided again to accommodate either IVB or IVT treatment methods. Both visual acuity (VA) and central retinal thickness (CRT) were measured after 6 months of treatment and compared with baseline measurements.

Significant improvements

It was found that all patients had a significant improvement of VA and CRT (Figure 1). However, there was a higher level of improvement for the IVB treated group with early onset of BRVO when compared with the patients that had undergone IVT treatment. "These results were in line with our previous experimental studies," added Dr Rehak. "This demonstrates the fast-up regulation of VEGF in acute ME."

Additionally, the opposite result was true for the late treatment group, so the IVT treated patients were found to have improved more than the IVB patients, however, the difference was not significant. "The inflammatory factors were up-regulated over a much longer time and played a role in the pathogenesis of chronic ME," he asserted.

Dr Rehak explained that VEGF is one of the most important factors playing a role in the pathogenesis of ME but he warned that there are several further genes that are up-regulated in the ischaemic retina. "In the rat model for vein occlusions, we found that the over expression of VEGF is very fast and can be detected predominantly in the first days after the development of the vein occlusion," he said. "This might be the explanation for the results we observed. Anti-VEGF drugs seem to be the best choice for the acute stage; the benefit of steroids is more pronounced in the chronic ME."