All those celebrities in oversized sunglasses might be doing more than shielding themselves from the paparazzi: Large lenses, especially those that fit the contours of the face, provide better protection from the sun's rays.

But those big, round frames come with a different sort of risk, albeit a minor one: The wearer might be mistaken for a fly, bee or other bug-eyed creature.

"The oversized bug eye is a trend that started in Hollywood," says Rene Soltis, an optician and director of education and training for the Vision Council. "A lot of trends start in celebrity land and then middle-class America tries to imitate and emulate. It appeared the more waifish the person was, the bigger the glasses. That's one of the things we're still scratching our heads over."

Not that questions about the look, which largely can be traced to Jackie Onassis and revived by starlets such as Mary-Kate and Ashley Olsen, have ever hampered its popularity.

And, says Eden Wexler, spokeswoman for manufacturer Safilo USA, the bug-eye glasses are probably here to stay as technology has improved to allow for curved frames and the public becomes more interested in getting shade from their shades.

Safilo holds the licenses for Giorgio Armani, Marc Jacobs and Christian Dior, among others, and owns the Solstice chain of stores.

The Dior Glossy frames kicked off the trend with fans including Lindsay Lohan and Katie Holmes, Wexler says, while the newer Dior Mixt frame keeps the large lenses but has a squarer shape.

The roundest of all might come from the debut Balenciaga collection, which emphasizes its circular shape with curved arms that dip right at the temple. For old-school glamour, there's a new oversized cat-eye from Jimmy Choo.

Some brands are taking the bug-eye thing seriously. Prada's "it" sunglasses of the summer are the shape of a butterfly, and Lilly Pulitzer puts a butterfly icon on its frames.

In the same spirit are Boucheron's serpent logo and Jimmy Choo's use of a watersnake treatment on the arms.

Trends in sunglasses shapes don't necessarily change from year to year, because once people find the shape that they feel best suits their face, they tend to stick with it, says Michael Hansen, vice president and general manager of the upscale retail chain Ilori.

Soltis says the oversized frames are a win-win situation for the wearer because they make a fashion statement and provide extra shade from the UV rays.

"Everyone is paying attention to skin cancer and the skin tissue around the eye is very delicate," she says. "Oversized frames do give more protection on the face, and they also give more protection on the sides, which means less squinting. Squinting goes against the young, fabulous and firm mindset because you get crow's feet."

Soltis acknowledges, though, bug-eye glasses probably are not for everyone. She suggests the following alternatives:

• Glasses with a forked arm piece tend to have wider arms but also offer good visibility.

• Modified aviators have a contoured lens so they're more comfortable for people with high cheekbones.

• Wrap-style sunglasses now have a greater depth to make them more wearable, but they still have limitations with prescription lenses.

Hansen notes that the bug-eye shape tends to be a feminine one. He recommends men stick with classic aviators or something like the Ray-Ban Wayfarer, although there are some sunglasses with pronounced hinges and thicker arms for the fashion-forward man.