This is a quick, practical style guide to choosing the right pair of sunglasses. The things to consider when buying your next pair are UV ray protection, lens color, lens material and overall fit. Let's start with protection.

UV Rays
Overexposure to UV rays can lead to serious eye problems. Make sure the glasses you get have a label indicating protection against at least 99% of UVB rays and 95% of UVA rays.

Lens Color
Each lens color provides different levels of color distortion and shape contrast. Different colors are good for different activities.

• Gray lenses simply reduce light intensity and don't affect either contrast or color. Default for any situation.
• Brown lenses block some blue light, thus slightly enhancing contrast, especially in snow. Good for snow sports.
• Amber/Yellow lenses block all or most blue light, providing superior contrast. Popular amongst hunters who need to distinguish shapes against the sky or light fields. Not good for color recognition, however, so avoid using while driving.
• Red/Orange lenses are good for providing contrast on overcast days.
• Violet lenses allow you to see shapes against green backgrounds. Good for hiking/camping/hunting in forest settings.
• Blue or Green lenses enhance contrast with yellow objects. Popular amongst tennis players.

Lens Material
The most expensive lenses are made of NXT polyurethane. They are impact resistant and flexible, lightweight and very clear. Glass lenses are heavy, very clear, but not very impact resistant, and they can be as expensive. Polycarbonate is what most generic-brand glasses are made of. They're not very scratch-resistant or as clear. Acrylic lenses are the least quality lenses available, but they are the cheapest.

The style you choose is up to your own personal tastes. Here are some of the most common sunglasses styles.

• Mirrorshade: popular with law enforcement. Gray and highly reflective.
• Aviators: teardrop-shape, shiny gray lenses with metal frame. Used by pilots, cops and military personnel.
• Wayfarers: 50s/60s retro glasses with thick frames. Worn by Audrey Hepburn in Breakfast at Tiffany's.
• Teashades: Made famous by John Lennon. Small, round lenses, that don't keep light out too well.
• Wraparounds: uses in sports. Tight fitting, slick and tough.
• Oversized: Hollywood glamour, very urban look.

Do they fit?
Finally, the most important question is whether the next time you choose prescription sunglasses in San Diego for yourself, make sure they are comfortable and they distribute weight evenly between ears and nose and that your eyelashes don't touch the lenses.