For about 64% of Americans, prescription glasses are both medical devices and fashion accessories. Not only can they correct your eyesight, but they can also help you tell the world faster what you want others to think of you.

However, even a simple pair of glasses can easily cost you hundreds of dollars. This is especially true if you buy glasses in a doctor's office or an eyewear chain store in the traditional way, or if your degree is more complex. Online retailers, like hypermarkets, offer ways to save money, but you may get less guidance and fewer options for frames. These choices and trade-offs can be overwhelming.

Therefore, we surveyed more than 91000 readers and personally bought glasses online and in brick-and-mortar stores to understand the advantages and disadvantages of different suppliers. We also interviewed glasses experts and ophthalmologists to get their best advice. We have come to the conclusion that where to buy discountglasses should depend on your priority of convenience, service, choice, or the lowest price.

Doctor's office and independent optician shop. Nearly 40% of respondents bought glasses from one of these channels. They spoke highly of the sellers' lens and frame matching, staff knowledge and follow-up service. But frames and lenses tend to be more expensive than elsewhere: our readers spend a median of about $400, two to three times as much as online or discount stores.

Big glasses chain. It is convenient to buy glasses in the glasses chain store because it has many branches. If there is something wrong with the glasses, you can get help there. Our readers report that the follow-up service of most chain stores is also very good. But in other ways, the survey score varies from company to company.

Warby Parker and Zenni Optical. Both stores sell only their own brands of glasses. Warby Parker is sold online (they mail you up to five frames to try on at home for free) and in brick-and-mortar stores in 18 states, the District of Columbia, and Ontario, Canada. In the seven years since its launch, Warby Parker has become a major optician, offering unifocal lenses for $95, including anti-reflective coatings. But if you order progressive lenses, the price will soar to nearly $300, much higher than the prices we found at some other retailers. Warby Parker's warranty on frames is only 30 days, while some other stores have a full year's warranty.

As for online retailer Zenni Optical, you can only virtually try on the frame by uploading a picture of yourself. It also has a 30-day warranty. Nonetheless, Zenni frames with basic unifocal lenses start at less than $10 and upgrade to progressive lenses starting at $28. Respondents who bought a full pair of glasses at Zenni spent a median of just $69, making it the lowest-cost retailer in the survey.

Large discount chains. Costco and Walmart are low-cost one-stop spots for buying eyeglasses where you can do everything from having your eyes examined to getting your finished glasses adjusted for fit. Frames can be inexpensive at these stores. At Walmart and Sam's Club, we found basic, plastic progressive lenses for as little as $79. Costco charges $130 for high-definition progressive lenses, which, as with all Costco lenses, include an anti-reflective coating. That's about half what you'd pay at many walk-in stores. But if you need basic, plastic single-vision lenses, you can pay as little as $29 at Walmart, about half as much as at Costco.

These retailers got high marks from readers, with Costco, our top-rated eyeglass retailer, edging out Walmart in several areas, including the quality of frames and lenses and follow-up service. However, readers were not impressed by the selection of frames, especially at Costco. One workaround: You can usually have a discount store put lenses into frames you purchased elsewhere. Walmart charges an extra $10 and Costco $18 to do this. They'll also adjust the frames while you're there.

Online retailers. While only about 5 percent of our respondents bought their glasses online, nearly twice as many browsed online before purchasing at a walk-in store. Even if you don't plan to buy from a website, the price information you get might help you negotiate your way to a discount from a walk-in store. For instance, in a web search, we found a Dolce Gabbana men's frame that was $190 at LensCrafters on sale for $99 at LensesRx Optical and $89 at Amazon.com.

But no matter how good an online retailer's tools, prices, and return policies, getting your glasses by mail can be a hassle, especially if you have to send them back.