Jennifer Aniston's natural-looking brows put her in Ruder's top four, along with Nicole Kidman, Jennifer Lopez and Lindsay Lohan.

If eyes are the windows to the soul, then many Hollywood celebrities need to pay better attention to their curtains.

Some are letting their eyebrows grow wildly out of control, while others are oversculpting to the point of absurdity.

Raisa "Raya" Ruder, a skin and eyebrow specialist for 15 years and owner of Raisa Laser and Skin Care clinic in West Hollywood, has plucked Renee Zellweger and Molly Sims and helped "feminize" Madonna's squarish brows before the diva kicked off her summer tour.

"People look very different when they have their eyebrows done," says Ruder, who received dermatology training in her native Russia. Eyebrow sculpting, when done properly, she says, "can open your face, give you more definition and help you express yourself."

She advises women to have their eyebrows done every three to five weeks, while men should avoid overshaping their brows.

"Just clean them up," Ruder tells the guys.

But just because you like J. Lo's brows doesn't necessarily mean you should pluck your own to look like hers. "Everybody is different, and someone else's style might not be right for you," Ruder says.

"You have to work with what you have."