Before getting an eye examination, you should familiarize yourself with the basics of lenses and frames.

For low price and optical quality, CR-39 plastic lenses are the best choice. (We found prices ranging from $29 to $129 for single-vision lenses.) But they are less shatter-resistant than other lenses, and with strong prescriptions they look like Coke bottle bottoms. If you are active in sports, you should instead choose polycarbonate lenses ($50-$180). For a strong prescription, get thinner polycarbonate, high-index ($49-$275) or Trivex ($100-$135) lenses.

When shopping for frames, keep in mind that plastic frames break more easily than metal ones, but they are fine for people susceptible to allergies.

Metal frames made of stainless steel or titanium also are non-allergenic, unlike those made of nickel alloy, which can irritate the skin. If durability is a concern, you should choose titanium frames and titanium-based flexible metals.

Prices for lenses alone can vary dramatically.

LensCrafters, for example, charged $120 before any discount for C-39 lenses. That’s five times the price we found at one Costco store. Sam’s Club also scored high for low prices. Overall, smaller chains, independents and private medical offices provided the best service, according to our survey respondents.

As for frames, we discovered that the Internet is a great place to shop. Prices are generally lower than at many brick-and-mortar stores.

For the complete package, you can enter your prescription and order your glasses at a Web site, or buy the frames there and have the lenses made at a store, where an optician can do a fitting. Expect to pay extra for this service, though: It’s $18 at Costco, for example, and $20 at Wal-Mart.