A blind man walking with his guide dog was punched repeatedly when he asked a van driver to move off the pavement to enable him to pass.
Tony Webb, 73, was attacked in Bishop's Stortford in Hertfordshire at about 09:00 GMT on Sunday.
His daughter posted a photograph of his black eye which has been shared by more than 15,000 people on social media.
She said he was recovering at home but was very shaken and was "petrified" of going outside.
Tracy Hassell, who said her father can see some light and dark, wrote on Facebook: "My blind dad was attacked in Bishop's Stortford town centre this morning at 9am by a man... who was parked on the pavement in a white van."
'Didn't believe he was blind'
She told the BBC: "Dad asked the driver if he would move so he and Sammy, his guide dog, could get past, but the man said 'no'.
"Dad asked him again and said it was out of order to park on the pavement, and the next thing he knew he was pushed up against the van - he thinks he was punched three times in his eye.
"The man even told my father he didn't believe he was blind."
Mr Webb was taken to hospital and later discharged.
Mrs Hassell said her father had tried to take Sammy for a walk early on Monday, "but he didn't get far - he said he was absolutely petrified there might be someone behind him".
A spokesman from the charity Guide Dogs said the organisation was "appalled" by the attack on Mr Webb.
"We have been in touch with him to ensure that he and his guide dog are both OK and will continue to support them in any way we can.," he said.
Police confirmed they were investigating "a physical altercation following a dispute about parking".