What would happen to your eyes if you looked at the eclipse without glasses?

Experts say it's always dangerous to look at the sun with the naked eye, as a blast of focused light directly from the sun can damage the photoreceptors in your eyes.

An eclipse can be an especially risky time to look at the sun, according to Suzanne Fleiszig, a professor of optometry and vision science at Berkeley's School of Optometry. While the sun is partially obscured, some wavelengths that trigger pain don't come through, dulling a person's reflex to look away, but enough rays will get through to damage your eyes.

According to experts, two main types of injuries can come from looking at the sun — a burn to the outside of your eye and damage to the nerve tissue within your eye.

"You can get a little bit of a burn to the surface of the eye, or what we call solar keratitis," said Daniel Lattin, an ophthalmologist at Nemours Children's Health. "You can get sort of a burn to that cornea, and that'll cause redness and tearing and those sorts of symptoms. That should resolve on its own, within a day or two, without any sort of permanent damage."

According to Russell Van Gelder, an ophthalmologist at University of Washington Medicine and director of the Karalis Johnson Retina Center, that type of injury is rare and is typically associated with climbers who spend time at high altitudes without proper eye protection.

"It's pretty hard to get that eclipse gazing; you need a fair amount of exposure," he said.

The symptoms to watch out for

Solar retinopathy, which is damage to your retinas from looking at bright lights, can permanently affect your vision, according to Seth Laster, an optometrist in Arkansas, and experts note the damage isn't always evident right away.

If you looked at the solar eclipse without protection or with faulty glasses, you should pay close attention to any symptoms. According to Laster, if your vision is blurry or if you see gray spots that don't go away, you may have suffered damage to your retinas.

"I tell people, 'Hey, if you're looking at something [and] a part of the image is missing, definitely come in and see your local optometrist," Laster said.

"If you have symptoms of a blind spot, wavy lines, floaters, or blurry vision, that could be solar retinopathy after this eclipse, and you need to be seen right away," said Luxme Hariharan, chief of ophthalmology at Dayton Children's Hospital.

Hariharan said solar retinopathy symptoms typically develop within 24 hours after sun exposure, and noted the condition isn't associated with pain.

"It's not a pain sensation," Van Gelder said. "The retina is devoid of the sense of pain or temperature. The retina can't feel when it's injured."

"Viewing the sun is often like getting a sunburn," said Tamara Oechslin, an optometrist and associate professor at the University of Alabama at Birmingham. "You don't notice the worst of the damage until an hour or two later."

According to Lattin, there's no treatment for solar retinopathy, however, some patients' eyes will recover over time.

The main thing to pay attention to is how long your symptoms last, said Carl Jacobsen, a clinical professor at Berkeley's School of Optometry. If problems persist after using eyedrops or if blurry shapes continue after you close your eyes, you should see your doctor.

"There's so many different things that can happen with people's eyes," Jacobsen said. "And we can never go wrong by saying, 'Call your eye doctor right away.'" (Wu, Washington Post, 4/9; Bush/Bendix, NBC News, 4/8)

Millions of cases of skin cancer are diagnosed every year, and many of them have been linked to ultraviolet (UV) radiation from the sun. Writing for NPR's "Shots," Allison Aubrey offers six expert-backed tips on how to protect your skin from sun damage this summer.