He said: "I was waiting for the burning feeling. It was terrifying.
"Acid attacks are becoming more and more common and I thought my family were the next victims."
All three victims - Roy and his son and grandson - ran into the back of the shop to wash their faces.
They then armed themselves with tools before chasing after the robbers.
One of the attackers swung an axe at Mr Thompson, which struck him a glancing blow.
The getaway car was also driven at him but he managed to jump out of the way.
In his statement to the court, Mr Thompson said: "It is fortunate for the guilty parties that the ammonia burns we received to the skin on our faces and in our eyes did not turn out to be a lifelong debilitating injury.
"Had the assailant with the axe struck me with the blade instead of glancing me with the blunt edge I could have been hospitalised or worse.
"It is ridiculous and a bad judgement on their part to risk so much for a mere motorcycle. The only use for which is having fun.
"Given that we have a retail business open to members of the public and have spent tens of thousands of pounds on security, we are now totally at a loss as to how we can stop anything like this happening in the future.
After the case, Detective Inspector Dave Watts of Wakefield CID, said: "This was a very serious offence in which Braham and his teenage accomplice sprayed their victims with an ammonia based substance, clearly risking causing very serious injuries.
"We are pleased this has been recognised by the courts and reflected in the sentences they have both received today.
"They were caught following extensive searches by colleagues including Wakefield uniformed officers and the National Police Air Service after engaging in some truly reckless and dangerous driving in trying to flee the scene.
"Those who think it is acceptable to behave with this level of lawlessness in Wakefield should be prepared for the police to stop at nothing to hunt them down, arrest them, and put them before the courts to face justice.