Abstract
Purpose: :
To report a series of eyes that failed to respond to anti-VEGF therapy with intravitreal bevacizumab in neovascular AMD, either primarily or secondarily after prolonged successful treatment. All eyes subsequently demonstrated a successful response to intravitreal ranibizumab.
Methods: :
The medical records of all eyes treated with intravitreal anti-VEGF therapy for neovascular AMD by a single retinal specialist from January 2006 until November 2010 were reviewed. Eyes that had received treatment with both bevacizumab (IVB) and ranibizumab (IVR) were then reviewed to identify eyes that received initial treatment with bevacizumab and then were switched to ranibizumab due to failure to respond to bevacizumab either primarily or after prolonged successful treatment. Visual acuity (VA) and OCT center subfield thickness (CSFT) were used to monitor response to treatment. Failure was determined by worsening vision or fluid on OCT.
Results: :
A total of 291 eyes were identified that had received anti-VEGF treatment for neovascular AMD. Eight eyes (2.7%) were identified that failed to respond to IVB treatment. Two eyes (0.7%) failed primarily and 6 eyes (2.0%) failed after prolonged successful treatment. Duration of treatment in the secondary failure group ranged from 78 weeks to 184 weeks with a mean of 140 weeks. The mean number of IVB treatments before primary failure was 2.5 and before secondary failure was 20.7. The mean initial VA was 20/40 and the mean initial CSFT was 269. At the time failure was determined, the mean VA was 20/50+1.5 letters and the mean CSFT was 273. All eyes that failed IVB treatment subsequently improved after treatment with IVR. At one month after initial IVR, mean VA was 20/40-0.5 with a mean gain of 3 letters and the mean CSFT was 229 with a mean improvement of -44 microns. After improvement with IVR 6 of the 8 eyes were again challenged with IVB. Once again, all 6 deteriorated with IVB and then had improved VA or CSFT one month after repeat IVR. The majority of eyes have continued with IVR therapy. At last follow-up mean VA was 20/50-2 and mean CSFT was 234 microns. This is a mean reduction of 39 microns in CSFT with a mean gain of 3 letters since the onset of IVR therapy.
Conclusions: :
Failure of bevacizumab therapy for neovascular AMD is uncommon but can occur, particularly after prolonged therapy. However, this does not preclude a successful response to subsequent anti-VEGF therapy with other agents, in this instance ranibizumab.
Keywords: age-related macular degeneration