The era of biological agents for the management of neovascular age related macular degeneration was firmly ushered in when two randomised controlled clinical trials in 2007 found that ranibizumab, a monoclonal antibody to vascular endothelial growth factor, improved visual outcomes in patients with this condition.1 2 However even before the original trial data were released, ophthalmologists had already begun to treat patients with neovascular age related macular degeneration with bevacizumab (the parent molecule of ranibizumab), which is licensed for intravenous administration in advanced colorectal cancer. In the linked study (doi:10.1136/bmj.c2459), Tufail and colleagues report their findings from the ABC Trial, a multicentre randomised controlled study that compared the use of bevacizumab and ranibizumab for the treatment of neovascular (wet) age related macular degeneration.3

Originally ophthalmologists administered bevacizumab intravenously but soon changed to intraocular delivery because of the potential for systemic adverse events.4 5 Intraocular delivery vastly reduced the dose of bevacizumab, which meant that the commercially available preparation (for intravenous use in the treatment of cancer) could be dispensed into hundreds of 1.25 mg …