The SCORE study showed that intravitreal triamcinolone was no more helpful than standard therapy (macular laser) in improving vision in patients with branch retinal vein occlusions (BRVO), and thus the SCORE study concluded to continue using standard therapy to treat BRVO. The question is, might another agent, say a VEGF inhibitor like bevacizumab (Avastin) be helpful in treating BRVO?
We get some indirect answers in a study published in the November/December issue of Retina. The study (Comparison of two doses of intravitereal bevacizumab as primary treatment for macular edema secondary to branch retinal vein occlusion: results of the pan american collaborative retina study group at 24 months) by Wu et al and the Pan-American Collaborative Retina Study Group was a retrtospective multicenter study looking at results from 63 eyes treated with two different doses of bevacizumab: 1.25 mg and 2.5 mg. Other studies had shown benefit in visual acuity and central macular thickness (CMT) with bevacizumab in BRVO, and the authors wondered if an increased dose may improve the visual outcome or decrease the frequency of injections. Patients with macular edema were given bevacizumab at one of the two doses (depending on the center they visited) and were examined on a monthly basis. OCT’s were performed at months 1, 3, 6, 12 and 24. If at any time the OCT measured CMT > 250 microns, they were classified as “recurrent” or “persistent” macular edema, and were re-injected. Re-injections were also given if visual acuity decreased by more than 5 letters (1 line).
Their study found that there was no additional benefit from the higher dose, and that both groups experienced improved vision and decreased CMT. The results showed that on average, CMT improved from about 450 mic at the first visit, to 250 mic at 3 months, and ended up at the 240 mic range at 24 months. Furthermore, the mean time for repeat injections was in the 10-13 week range.
But is this better than laser? Well, the study doesn’t directly look at this question, but it does state that among its small sample size of 63 eyes, of those receiving 1.25 mg, 68% experienced improvement in vision by 3 or more lines of vision (72% in the 2.5 mg group). That’s pretty significant percentage of improved vision. You’ll recall that the SCORE Study patients had improved vision in the 26-29% range for IVTA and laser. So bevacizumab seems to give better results than laser for BRVO. I realize I’m mixing studies — not really a meta-analysis (maybe a “mini”-analysis), and clearly this needs to be studied further. But the authors seem to lay out a reasonable approach for treating BRVO with bevacizumab, and their results seem to be significantly better than best results we have available with laser or IVTA. Check vision monthly, and if worse by 5 letters, treat with bevacizumab; check OCT at 3, 6 12 and 24 mo, and if CMT > 250 treat with bevacizumab. Expect about 70% to improve 3 or more lines of vision.