Michael Howard caught Tony Blair by surprise at prime minister's questions yesterday when he claimed government delays on eye treatments would mean 2,800 people losing their sight.

Health chiefs were given nine months rather than three to introduce treatment for a form of acute macular degeneration after clinical watchdogs approved its use in September to combat the most common cause of blindness among elderly people.

Mr Howard said claims by John Reid, the health secretary, that it had been delayed because of staff shortages were rejected by the Royal National Institute for the Blind, which had come up with the figure of 2,800. The RNIB had said there were 50 centres which "could provide the treatment today".

Mr Blair said he was unaware of the situation but would "look into it very carefully". He said he understood from Mr Reid, who was sitting next to him, that the extension in implementation had been agreed by the National Institute for Clinical Excellence and that the number of NHS training places had increased "massively" since 1997. Before taking further action, he wanted to be sure the Tory leader was "being entirely accurate with the facts".