Did you look up at the solar eclipse without your safety glasses? Looking at the sun — even when it's partially covered like during the eclipse on April 8 — can cause eye damage.

There is no safe dose of solar ultraviolet rays or infrared radiation, said Dr. Yehia Hashad, an ophthalmologist, retinal specialist and the chief medical officer at eye health company Bausch + Lomb.

"A very small dose could cause harm to some people," he said. "That's why we say the partial eclipse could also be damaging. And that's why we protect our eyes with the partial as well as with the full sun."

But how do you know if you've hurt your vision? We asked eye doctors what to know.

Is it a sign of eye damage if your eyes hurt after looking at the eclipse?

Your eyes likely won't hurt if you look at the eclipse without protection — but that doesn't make it any less dangerous.

In fact, the painlessness is part of why the event is so concerning to eye care professionals, said Dr. Jason P. Brinton, an ophthalmologist and medical director at Brinton Vision in St. Louis. 

"Everyone knows don't look at the sun. If you go out on a bright day and try to look at the sun — it's very uncomfortable, very bright. So most people intuitively associate that with something they should not be doing," Brinton said. "But with the eclipse, so much of that is blocked and so that natural sense of discomfort and aversion to the brightness is not there."

In some cases, the sun can also damage the cornea, which can be painful, Brinton says.

"The good news is that this fully heals without lasting issues, so this is why we don't think about this aspect as much. The retinal issues, on the other hand, are painless and can have permanent, lasting effects on vision," he said.

What are other signs of eye damage from looking at a solar eclipse?

Hashad says there are a few "alarming signals" to be aware of, including: 

• Headaches
• Blurred vision
• Scotomas, or dark spots: "You just see a black area or a black spot in the field of vision," Hashad said. 
• Color changes: "You don't see the colors the same way you were seeing it before," he said.
• Distorted lines: Hashad says this is clinically known as metamorphopsia, which makes lines appear warped, distorted or bent.

"This could be happening unilateral or bilateral," he said. "So it doesn't necessarily happen in both eyes. It could be affecting one over the other or both eyes together."

Issues may not be apparent immediately, either, sometimes appearing one to a few days following the event.

And while some will regain normal visual function, sometimes the damage is permanent. 

"Often there will be some recovery of the vision in the first few months after it, but sometimes there is no recovery and sometimes there's a degree to which it is permanent," Brinton said. 

What should you do if you show symptoms of eye damage?

If you're experiencing any symptoms of eye damage, Hashad suggested people "immediately" seek an ophthalmologist's advice.

"Seeing an eye care professional to solidify the diagnosis and for education I think is reasonable," Brinton said. 

Unfortunately, there isn't a treatment for solar retinopathy, the official name for the condition.

"Right now there is nothing that we do for this. Just wait and give it time and the body does tend to heal up a measure of it," Brinton explained.

That is why prevention is so important, and remains the "mainstay of treatment of solar retinopathy or solar damage to the retina," Hashad explained. 

How long is too long to look at a solar eclipse without glasses?

Any amount of time looking at the solar eclipse without glasses is too long, experts said.

"Damage from the solar eclipse could happen to the retina in seconds," Hashad said. "That's why we don't want people to stare even for a short period of time — even if for a few seconds to the direct sun — whether eclipsed or even partially eclipsed."

In:
• Eclipse

Sara Moniuszko

Sara Moniuszko is a health and lifestyle reporter at CBSNews.com. Previously, she wrote for USA Today, where she was selected to help launch the newspaper's wellness vertical. She now covers breaking and trending news for CBS News' HealthWatch.

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