Tragically, Keith’s daughter was also recently diagnosed with the same condition and will also lose her sight.
He said: “It was quite tough for me to have to see her witness this, it could be a glimpse of what she has to face in the future.”
Keith added: “I was just speaking very clearly because I wanted the other people around us to hear.
“We didn’t feel safe in that situation.
“I just kept repeating ‘I will not leave the shop, I have a right to be here, I have a guide dog’.”
The 55-year-old said the manager then asked staff to “put the cameras” on him and his daughter, and even threatened to call the police.
Keith said: “I asked my daughter what we were going to do and she insisted that we stand our ground. So we just carried on shopping.
“My daughter went and paid for our food at the self checkout while I stood and waited for an apology.
“I just thought if we left the store now I’d never be able to use it again. It’s the shop on my trained route.
“The manager came back and said ‘the rules have all changed recently, so I’ll let you off’. I just thought ‘you’ve got to be joking’.
“I was actually shaking. When I came out I was just miserable. It’s a horrible feeling.”
Keith has formally complained to the store who told him an email: “I am sorry to hear about your most recent visit to our Wapping London Dock Local store whereby the duty manager and two staff members asked you to leave due to your guide dog, I understand how upsetting this would have been, I do hope you are okay.
“I would like to confirm, as stated on our website, assistant dogs are absolutely welcome in our stores and petrol stations. I will be contacting the stores management team to highlight the concerns you experienced. Please be assured we have taken this seriously and appropriate action will be taken.
“Thank you for bringing this matter to our attention.”
A Sainsbury’s spokesperson said, “We are in touch with Keith to apologise.
“We have a clear policy which welcomes guide dogs into our stores and we are investigating his experience and reminding all colleagues of our policy.”