It was like being "trapped in a nightmare," says 61-year-old Colin Farmer, a blind stroke victim from Chorley in Lancashire, of his recent run-in with police that ended with him being tased and cuffed for no apparent reason.

After "a number of reports" were received of a man armed with a samurai sword strolling through Chorley, police were dispatched to the scene only to encounter Farmer, who was walking "at a snail's pace" with his white cane.

Giving him no time to explain, officers shot Farmer in the back with a 50,000-volt Taser, sending him crashing to the ground.

"I thought I was going to be attacked by hooligans," Farmer recalled.

Despite his efforts to notify officers of his blindness, Farmer was dragged and cuffed, leaving him bruised both physically and mentally. "[I] was absolutely terrified," he said.

Farmer was taken to hospital by officers who stayed with him throughout his treatment and later drove him to a friend's house.

The department has since released an apology, saying "we have clearly put this man through a traumatic experience and we are extremely sorry for that."

A full investigation has been launched by the Independent Police Complaints Commission.

Police in Lancashire did eventually track down the man with the samurai sword: A 27-year-old was later detained temporarily on suspicion of being drunk and disorderly.

[photos via Lancashire Police]