My father started losing his eyesight in his late 30s and eventually was diagnosed with a degenerative condition called retinitis pigmentosa. Doctors declared him legally blind and instructed him to turn over his driver’s license when he was 40.

He lost all of his vision along the way, now totally blind at 78.

Having witnessed my dad’s struggles, his frustration and his occasional sadness for nearly four decades, my hope is that Vikings coach Mike Zimmer focuses on his long-term health above anything else.

Jeopardizing his eyesight is not worth one NFL game, or two, or the rest of the season, if that happens to be the case.

Far be it from me to tell someone how to live their life, but the Vikings hope Zimmer is their coach for a long time. Missing a few games this season, even as his team fights to make the playoffs, shouldn’t override Zimmer’s health and doing what’s best for him.

Apparently, Zimmer has accepted that fact, however reluctantly.

“I can’t express how hard it is on Coach not to be able to coach,” General Manager Rick Spielman said.

Zimmer agreed to miss Thursday’s game vs. the Dallas Cowboys after undergoing emergency surgery to repair a detached retina. He reportedly listened to the game from home.

If Zimmer needs to miss next week’s game at Jacksonville too, or others after that while he recovers, so be it. Everyone at Winter Park will rally around him.

We all know Zimmer is a tough guy. His fierce determination and competitive spirit are admirable. His take-no-guff personality makes him who he is and has endeared him to Minnesotans.

Remember Zimmer’s angry response last season after Teddy Bridgewater got knocked out of the St. Louis Rams game by a cheap shot?

“If we were out in the street,” Zimmer fumed, “we probably would have had a fight.”

His serious eye problem requires a calm approach and willingness to treat his health as more important than devising new blitz schemes.

Football coaches are wired differently than most. They’re often obsessive control freaks who believe the only way to win is to outwork everyone else, 18-hour workdays at a time.

They sleep in their offices, study video until exhaustion and then get up and do it again the next day, week after week. Many times they put their own health far down the list of priorities.

Zimmer already had endured two eye procedures before this emergency surgery. His right eye looked awful as he conducted a regular weekly news conference after the second surgery.

Zimmer refused to miss work, saying his eye felt OK.

“Back to the grind,” he said.

He later noted that he was encouraged by how his team performed in a loss a few days earlier.

“If I had to get six needles stuck in my eye the last two weeks,” he said, “then they could suck it up for me.”

His coaches and players can still do that while he recovers. In a conference call with reporters Thursday morning, Spielman sounded like he basically had to order Zimmer to stay home. Zimmer had never missed a game in his long coaching career.

“As hardheaded and as tough-minded as he is, we had some pretty significant talks one-on-one, heart-to-heart about what is important in life and what isn’t,” Spielman said. “You have to look out for your long-term health. That’s the No. 1 thing everyone’s worried about.”

Good for Spielman for drawing a line and insisting that his stubborn coach put health first, team second. Maybe Zimmer would have come to that same conclusion, as painful as it undoubtedly is for a football lifer to be away from his team.

Hopefully Zimmer’s surgery fixed the problems without permanent damage and he’s able to return to coaching soon. And hopefully he doesn’t attempt to defy doctor’s orders and rush back before his eye is healed and not at further risk.

Zimmer needs to think about himself right now. Football can wait.