Sunglasses are the ultimate summer accessory. How do you find frames that fit your face? Opticians offer these tips:

If You Have a Round Face

Choose a rectangular or square frame. Jesse Winters of Bethesda’s Apex Optical says that sharp lines bring out the angles of a round face. Avoid round styles, which emphasize curves.

If You Have an Oval Face

Frames with strong horizontal lines make a long or oval face seem wider and shorter. June Mines, owner of These Eyes of Mines in Northeast DC, says a cat’s-eye frame gives the illusion of curves on a long, slender face.

If You Have a Square Face

A square face has a broad forehead and a wide chin. If this sounds like you, look for slightly rounded frames, which soften features. Winters says that round frames give people with strong jaw lines and angular faces “the fullness their face is missing.”

If Your Face Is Heart-shaped

Heart-shaped faces are broad at the forehead and cheekbones but narrow at the chin. Mines says frames with angles, such as rectangular or octagonal shapes, draw attention away from the top of the face.

For All Face Shapes

Here are other tips to keep in mind:

• Although oversize “Jackie O” frames are popular, make sure the bottom of the frame does not rest on your cheek. “Otherwise, every time you smile, your sunglasses will move up and down,” says Joost Voorthuis of Georgetown Opticians.

• Wraparound styles prevent rays from entering your eye through the side of your face. Bonus: They ward off crow’s feet and wrinkles around the eyes. If your prescription precludes wraparounds, frames with thick temples are a good alternative.

• If you spend a lot of time outdoors or on the water, consider polarized shades, which minimize glare.

•The most important job of sunglasses is protecting eyes from the sun’s ultraviolet rays. Lenses should offer 100-percent UV protection. Not sure yours do? Most optometrists are happy to test shades for free—and can do so in seconds.