It’s not polite to stare. And in some cases, it’s downright dangerous.

Take staring at the sun, for instance. As ophthalmologists and other eye professionals have long warned, looking directly at our nearest star can result in serious — and sometimes permanent — damage to one’s vision.

Still, come Aug. 21, it’s going to be awfully hard not to stare, what with a total solar eclipse making its way along the length of the United States.

So, what exactly happens — physiologically speaking — when you look directly at the sun?

“Obviously, the sun is emitting extreme amounts of radiation energy,” explained Dr. Craig Chaya, an ophthalmologist and assistant clinical professor at the University of Utah’s Moran Eye Center in Salt Lake City. “Basically, when you look at the sun, you’re taking all those rays and focusing them on one specific area of your retina — the very center of the retina.”

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 That retinal center is called the macula, and according to Dr. Robert Treft, an ophthalmologist with Mountain View Eye Center in Layton, it’s the most sensitive area of our straight-ahead vision.

“The macula is about the size of the head of a pin, and it’s responsible for all of our best vision,” Treft said. “If you have focused light on the retina, it can create a sort of burn damage.”

More accurately, it’s a type of photochemical damage. Treft said the photons of light entering the eye are so intense that they disrupt and destroy the cells on the retina, which leads to scarring and a loss of light perception. This can cause a blurred or dark spot before one’s eyes.

There’s a name for this damage. It’s called “solar retinopathy,” and it’s the greatest danger associated with looking directly at the sun.

“Basically, it’s a blind spot in the center of your vision,” Chaya explained.

Treft said some studies have shown it takes about a minute of staring at the sun to create this damage to your central vision. However, that time can be affected by the intensity of the light source, as well as individual sensitivity.

Recovery from less severe cases of solar retinopathy can occur spontaneously, according to Treft — usually over the course of three to six months. However, he warned such visual recovery may be incomplete, and the patient may suffer from permanent vision problems.

“Fortunately, the eye has a remarkable ability to heal itself,” Treft said. “You may recover some vision over the next three or four months, but no one can guess how much you’ll recover and how much you’ll be left with as a permanent deficit.”

And Chaya warned that while you might get away with short glimpses at the sun, there simply aren’t any guarantees. The damage can be cumulative and occur without any noticeable pain or discomfort, so the longer and more repeated the exposure, the more likely the damage will be permanent.

“There’s probably a point of no return, where that damage may be irreversible,” Chaya said.

Also, because the sun emits much more energy than just visible light, there can be more damage than, well, meets the eye.

“Different spectrums of light have the ability to penetrate at different levels,” Chaya said. “There are certain structures in the eye that are more sensitive to blue light, for example, than longer-wavelength lights. And because of the different frequencies of light that are coming out of the sun, it’s going to damage a spectrum of different cellular structures in the retina. That’s what makes it so intense.”

Chaya said solar retinopathy is actually more common than you might think. Although he doesn’t see a lot of these patients in his practice — “every couple of years I see one,” he estimated — Chaya knows doctors who deal with this type of eye damage regularly.

“My retina colleagues probably do have a handful of patients that have suffered from solar retinopathy,” he said. “Maybe as children they watched an eclipse, or you have some sun worshippers that have been under this impression that staring straight at the sun is a good idea, for whatever reason.”

Treft said he sees a few cases of solar retinopathy after each solar eclipse.

“Every solar eclipse that takes place, we will end up seeing some kids who will be brought into the office with sunlight damage from ignoring the suggestions and staring at the sun,” he said. “It’s usually elementary school kids, who kind of dare each other to stare at it.”

The majority recover fairly well, Treft said, but it’s a months-long process. And he does see the occasional patient with permanent burns to the retina.

“We need to help people understand this is a real danger, and they need to take it seriously,” Treft said.

Contact Mark Saal at 801-625-4272 or msaal@standard.net. Follow him on Twitter at @Saalman. Friend him on Facebook at facebook.com/MarkSaal.