An anti-blindness injection that a rival drugs manufacturer wants to prevent the NHS from using could save the health service £84m a year.

Avastin, which is used to treat wet age-related macular degeneration – the most common cause of blindness among the elderly – costs only £60 per injection.

But despite trials showing it is no less effective, another drug, Lucentis, is the current official choice, even though it costs £700 per shot.

Avastin is intended to treat cancer, but research by the National Institute for Health Research has shown that it also works just as effectively and safely as Lucentis in treating Wet AMD.

The study, presented at a conference by the Association for Research and Ophthalmology, looks set to further enflame a dispute between the NHS and the maker of Lucentis, Novartis.

Some doctors have been prescribing Avastin for the condition to save money, even though it has not licensed for this use. However, that has led Novartis to take four NHS trusts to court to prevent their doctors from doing so, arguing its unsanctioned use undermines patient safety.