The AMD disease leads to a progressive loss of sight
The NHS is looking into if it should break with convention and recommend the use of an unlicensed treatment for patients at risk of blindness.
Lucentis is the preferred option for wet age-related macular degeneration - but at £10,000 per patient on average it is a costly therapy.
However, it is derived from Avastin, a cheaper drug used for bowel cancer.
The National Institute for Health and Clinical Excellence is now reviewing whether that should be used instead.
The move, if agreed to, would be unusual, although by no means unprecedented - similar deliberations have been given to transplant drugs.
The official NHS advisory body normally only considers cases where the drug is licensed for the condition.
But the Department of Health has asked NICE to consider altering its normal procedures because of the unique situation.
Doctors across the world have used Avastin to treat wet AMD on an unlicensed basis by splitting it into tiny doses and injecting it into the eye.
NHS patients were also treated in this way until NICE backed Lucentis two years ago.
Both drugs are made by US-based Genentech, but it has so far refused to put forward an application for Avastin to be licensed for wet AMD use.
But the authorities in the UK are now looking at a way around the issue after the bill for Lucentis has risen faster than expected because patients are staying on it longer than expected.
At this stage, NICE is only considering whether they should fully investigate the possibility of recommending Avastin.
But the move has received the cautious backing of doctors and campaigners.
Cathy Yelf, of the Macular Disease Society, said: "This is an exceptional case and could lift some of the pressure on the NHS.
"But we need to get results from the trials currently going on into whether Avastin is truly safe and effective before a decision is taken."
Richard Smith, vice president of the Royal College of Opthalmologists, described it as a "simply good house-keeping" given the circumstances.
NICE said it was not expecting to make a decision until next year.