Greater Manchester Police Federation said one of the officers injured during a protest by Manchester United fans on Sunday suffered "life-changing" eye injuries.
An officer sustained a "significant" slash wound to the face during the unrest at Old Trafford, which caused the postponement of Manchester United's Premier League match with Liverpool when fans occupied the pitch.
Stu Berry, chairman of Greater Manchester Police Federation, which represents the force's rank-and-file, said the injured officer was a PC with around 20 years' service.
He said: "Our brave colleague went to work yesterday to keep the people of Greater Manchester safe - and he ended up coming under attack. He is incredibly lucky not to have lost the sight in an eye.
"This is not right. Police officers are mothers, fathers, husbands, wives and partners. They are sons and daughters. They are human beings who should be able to go home to their families in one piece at the end of their shifts. Not be rushed to hospital.
"We are offering support to our injured colleague and will continue to do so as he recovers from his injuries."
Berry believes a wider public debate is now needed around the kit officers wear during protests.
He said: “We are witnessing colleagues come under relentless attack wearing not much more than a flat cap and a high-vis jacket and with a baton to keep themselves safe.
"Our officers must be properly protected and appropriately equipped with public order gear - including helmets and shields - when policing these protestors.
“This will in no way be the last demonstration UK police officers have to encounter as the nation unlocks and our courageous colleagues are bearing the brunt of public frustration. They must have the appropriate kit available to protect themselves.
“Officers are not – and never will be - punchbags for people protesting for their cause. We have seen too many images of police officers at protests over recent weeks with blood gushing from their faces. How many more do we have to see? How badly does a police officer have to be injured before we do something?
“Our approach has to change. And it has to change now.”
