A study in the September 2009 issue of Retina by Huang et al. out of Taiwan is titled “Intravitreal Bevacizumab and Panretinal Photocoagulation for Proliferative Diabetic Retinopathy Associated with Vitreous Hemorrhage.” In this important study, they took 40 patients with vitreous hemorrhage (VH) too dense to treat with PRP, and if the VH did not clear within two weeks, they treated them with bevacizumab (Avastin). If the VH did not clear, they treated again in 4-6 weeks. If the VH heme had not cleared by 12 weeks, they performed a pars plana vitrectomy (PPV). They compared this to a group of 40 patients who did not receive bevacizumab. When the vitreous was clear enough in either group, they received PRP.
The results showed that patients receiving bevacizumab cleared anywhere from 2-20 weeks (avg 12 weeks), whereas the patients who did not receive bevacizumab required 6-30 weeks (avg 18 weeks) to clear. Only 10% of those receiving bevacizumab required PPV, whereas 40% of those who did not receive the drug required PPV.
So, clearly, intravitreal bevacizumab is helpful in the initial treatment of VH from proliferative diabetic retinopathy. It improves the rate of resolution of VH, and decreases the need for surgery. Two points were of interest to me. Neither was specifically studied in the paper, but the authors raise the issues in their study design . First, they remind us that bevacizumab can induce a fibrous response (“Avastin crunch”) and lead to tractional retinal detachments, and so they excluded patients whose ultrasounds showed the presence of tractional detachments or fibrous responses. They repeated the B-scans as they followed the injected patients to watch for tractional detachments. Second, they chose 4-6 weeks as the interval for re-injection of bevacizumab. They based this on two previous papers. One by Jorge et al. which showed that peak regression of NV in diabetic retinopathy occured at 6 weeks, and that by 12 weeks, leakage had resumed; and the other by Arevalo et al. which showed that regression of NV could occur as quickly as 7-15 days after injection of bevacizumab.
Pearls to take away: Inject bevacizumab for dense vitreous hemorrhages, get a baseline B-scan and follow the B-scans after injection for tractional detachments, and consider re-injections at 4-6 weeks.