A small but obvious tip for police: Don't accuse a man with a debilitating eye condition of "turning a blind eye" to drug dealers in his area. And then don't also hit him right in the eyes.

Yet that's exactly what a 74-year-old landlord accuses a group of City of Miami Police officers of doing. Fernando Coipel in a federal lawsuit says cops beat him while he was wearing "two protective eyeglasses" and a white eyepatch, all used to treat a condition that leaves him visually impaired.

Coipel's lawyers did not respond to multiple requests for comment. The City of Miami, meanwhile, does not comment on active litigation.

But Coipel outlines his allegations in the lawsuit, which he filed in February. He says the trouble began when he was talking to a prospective tenant at the apartment complex he owns on NW 61st Street in Miami on Valentine's Day 2012.

It was around 6 p.m. when Miami Police Officer John Carpenter approached Coipel from behind and said, "Put your fucking hands against the wall," Coipel alleges. Instead of waiting for Coipel to comply, the lawsuit says, Carpenter grabbed him by the back of his shirt and slammed his face into the wall.

“What’s going on?" Coipel claims he asked. "I am the owner of the building.”

Carpenter then allegedly responded, “Shut the fuck up. I don’t care who you are." He then slammed Coipel against his police cruiser several times, the landlord says.

"During this ordeal, Mr. Coipel kept on yelling, 'I can’t see,'" the suit says. "By this point, Mr. Coipel’s last pair of glasses had fallen to the ground and blood was coming from his right eye."

As a second officer arrived, Coipel says, his pants fell down, but Carpenter continued kneeing him, throwing him against the pavement, and hitting him on his back and head. Carpenter then finally told Coipel he was under arrest.

According to Coipel, the whole ordeal was caught on film: His prospective tenant was recording on her phone. After allegedly demanding the tenant stop filming, the lawsuit says, the cops then threw Coipel, whose pants were down, into a police cruiser.

With his eye still bleeding, Coipel slowly deduced why he was being detained. The cops allegedly drove Coipel to another spot in the neighborhood and pointed at two men, ostensibly drug dealers, and asked if he knew them. Coipel said no.

The lawsuit says the cops then arrested those two men and took them all back to the station. While there, Coipel says, he asked for water to help clean his bleeding eye. He says police said, "I'm not going to give you a fucking thing."

Police then finally told Coipel why they had arrested him: The lawsuit states the police accused Coipel of "turning a blind eye to people dealing drugs in his building." They threatened to take his building from him.

Coipel was charged with two counts of obstruction and one count of battery on a law enforcement officer. The charges were later dismissed.

Coipel later filed a complaint against the City of Miami Police Department, alleging abusive treatment, discourtesy, and improper procedure. (He also added that Carpenter had broken his ribs.)

On September 17, 2013, the city's Civilian Investigative Panel, which oversees internal affairs complaints against Miami Police, unanimously sustained the charges against Carpenter, as well as one allegation of improper procedure levied against Officer Kenya Crocker.

Coipel and his wife Ida then sued Carpenter, four other officers, and the City of Miami in February for multiple counts of false imprisonment, excessive force, assault, battery, failure to implement appropriate policies, and loss of his 14th Amendment civil rights.

Carpenter has since filed a motion to dismiss Coipel's lost-rights claim. The lawsuit is still winding its way through court.

Here's a copy of the complaint: