In order to safely watch the solar eclipse, you need special glasses to protect your eyes from the sun's rays. And if you don't know what to buy, you could be putting your vision at risk. Here's what you need to know.Buyer BewareReuters reports that a flood of fake glasses and other solar viewers has been hitting the market, and doctors are warning consumers to check before they buy. Some of them come with fake logos of reputable brands, or even fake safety labels. Peru State College in Nebraska mistakenly ordered 7,500 pairs of sketchy glasses, which were from a Chinese manufacturer, but found they were defective, and only came with the typical safety label that comes with normal sunglasses (they eventually ordered new ones.)If you bought your glasses on Amazon, check your email. The company notified customers who bought certain solar eclipse glasses from a third-party seller. They specifically emailed buyers of glasses that did not comply with industry standards, so if you did not receive an email, your product is likely still safe to use. If you want to double check, you can contact Amazon customer service.What Your Solar Eclipse Glasses Should DoWhen you use the proper glasses, your view should be completely dark, almost like you're wearing a blindfold, unless you're looking right at the sun. You shouldn't be able to see more run-of-the-mill brightness, like you do when you wear normal sunglasses. That's because solar eclipse glasses are around 100,000 times darker than typical sunglasses, so your normal pair won't cut it. When you look at the sun in eclipse glasses, it should be comfortable to look at, like you're looking at the full moon. If it's uncomfortable, not in focus, or hazy-looking, it's not safe and you should return your product. And if it's scratched, torn, or damaged, throw it away. What Can Happen If You Aren't ProtectedIf you don't use the approved glasses, or don't use glasses at all, you could put your eyes at severe risk. Consider it equivalent to using a magnifying glass to try and burn leaves on a sunny day. Your retinas magnify light from the sun in a similar way, says Dr. Russell N. Van Gelder, clinical spokesperson for the American Academy of Ophthalmology and professor of ophthalmology at University of Washington School of Medicine. So if you're not protecting yourself, you can literally burn your retinas—and because your eyes don't feel pain the same way the rest of your body does, you might not know it until it's too late. Dr. Van Gelder notes that people with eye damage come to him with a hole in their vision after gazing at the sun; it might look black, gray, or have a color. Only half of such patients will recover—the other half will lose the central vision in their eye. Even though they have peripheral vision, they can't see straight ahead, which affects the vast majority of your life. "At present we have no treatments for this," Dr. Van Gelder says. "There's no way to reverse the damage, so prevention is the only cure."How to Know If Your Glasses Are LegitAccording to the American Astronomical Society, it used to be sufficient to look for a label that had the international safety standard code of 12312-2. But now, some companies are printing that number on fake products, even if they don't block enough of the sun's rays. And some sellers are even putting fake safety test results on their websites. Instead, before you buy, make sure your product is on the AAS list for reputable vendors. "If we don't list a supplier, that doesn't mean their products are unsafe," AAS press officer Rick Fienberg said in a statement. "It just means that we have no knowledge of them or that we haven't convinced ourselves they're safe." The AAS also notes that if you got your viewer from a science museum or planetarium, or a professional astronomical organization, you are almost certainly good to go. How to Enjoy Sungazing SafelyThere's only one time you can look at the eclipse without glasses, and that's during the period of "totality," when the moon completely blocks the sun and the stars come out in the middle of the day. This will only occur in a 70-mile-wide path across the country, and it'll last slightly less than three minutes. So for most of the time, and in most of the country, you definitely need glasses. And if you are in the totality zone, you must put your glasses back on immediately after you see the slightest glint of sunlight post-totality. No matter where you are, there are extra precautions you need to take if you want to watch the eclipse in different ways. If you're planning on using a telescope, NASA warns you have to use a special solar filter or lens at the large end of the scope. The same goes for binoculars. And Dr. Van Gelder warns that if you want to take a photo of the eclipse with your cell phone, you need to put eclipse glasses over your phone's camera lens. And if you take your glasses off to take the photo, make sure that you don't look directly into the sun yourself. It's a tricky balance, but worth it if you want to protect your eyes while getting that perfect photo. Approved Glasses You Can BuyHere are a few AAS-approved eclipse glasses that were still in stock as of August 16. There's not much left, so you'll need to hurry, and be sure to check sites' shipping policies to see if there's still time to order. If you're out of luck, check your local library, because free pairs have been sent to libraries across the country. Free glasses may also be available at official NASA viewing sites. American Paper Optics, 10 packLunt Solar Systems, 5 packCPPSLEE, 3, 4, or 5 packFirefly Buys, from 3 to 20 packsEclipser HD, 1 pair