(INSIDE EDITION) — A 20-second look at the sun cost Lou Tomososki much of the sight in his right eye.

So he has some words of advice for kids and teens tempted to look at the upcoming solar eclipse: You’ll be sorry!

“Why take a chance with your eyes?” the 71-year-old Oregon man told InsideEdition.com Monday.

He was a teenager when his science teacher told the class about a solar eclipse happening that afternoon.

So he and his buddy, Roger Duval, stood in front of their high school and looked up. He remembers watching the moon pass over the sun.

He thought nothing of it at the time, he said.

“There’s no sign” that your eye is being damaged, he said. “You just squint. You don’t feel anything.”

On the walk home, “there was a little bit of a blurry spot,” he said. Luckily, he had looked at the eclipse with only one eye.

But even that left him with a pea-sized blank spot in his right eye.

“The damage was done right then and there,” he said of his 20-second glimpse of a solar eclipse. “The longer you look at it, the more damage is done.”

He didn’t realize that the sun had burned a hole in his retina until months later, during a visit to the eye doctor.

He couldn’t see past the second line of the eye chart when the physician told him to close his left eye and read the letters in front of him.

“The sun is 93 million miles away and look what it can do,” he said.

He and Duval, who’ve been friends since the fourth grade, are speaking publicly about the danger of looking at the rare celestial event on Aug. 21, when the eclipse will be visible in North America.

“If we can save just one person from looking up at that thing,” that will be enough to please them both.

“Why would you a take chance with your eyes?” he said.Click here for more articles and information about the Great American Eclipse.