What to look for when buying specs online

What to keep in mind as you shop for glasses online:

SELECTION
Framesdirect.com, a full-service online eyewear company, offers 100,000 frames and sells contact lenses. Also offering a generous selection is 39dollarglasses.com. Shopping them can be overwhelming. Warby Parker cuts the clutter, offering about 35 styles, all in acetate and most fairly chunky.

PRICE
If you need a strong correction or like extra-thin or tinted lenses, fees for those extras can add up. High-index lenses can add $30, for instance, and a strong correction another $30, though vendors charge in different ways for add-ons.

SHIPPING
Be sure to examine each company's fees, too. The site 39dollarglasses.com offers free shipping on all orders over $99. Warby Parker doesn't charge for shipping, including for up to five pairs you can try on for free as long as you return them within five days, while Eyefly.com -- launching in June -- plans to charge a flat shipping fee of $4.95 for standard delivery.

SERVICE
Remember that any fine-tuning or tightening you need after you've worn your glasses awhile will have to be done in person, and your local optician may charge for those services if you didn't purchase your glasses there.

RETURN POLICIES
Bestbuyeyeglasses.com, for example, doesn't allow full returns or exchanges but will give you 50 percent off new lenses if you exchange the pair of glasses within 30 days of purchase. Warby Parker gives you 30 days to decide if you like a pair of glasses and, if you don't, promises to refund your full payment.

QUALITY OF LENSES
While glasses assembled in the United States should at least have impact-resistant polycarbonate lenses, Sam Pierce of the American Optometric Association warns some foreign labs may use substandard materials.