Eyeglasses come with almost as many options as new cars. Some are functional, some are cosmetic, but all are available for most kinds of lenses.

Photochromatic lenses darken automatically in sunlight, then lighten when you go inside. If you don’t like switching between regular glasses and sunglasses every time you go through the front door, these may be for you. Photochromatic lenses are available in both plastic and glass, but plastic loses its darkening ability after a few years, while glass retains it forever. The degree and speed of darkening varies between different types of plastics.

All photochromatic lenses have UV protection, which blocks harmful ultraviolet rays and is available on all types of lenses. UV light is suspected of causing age-related eye diseases, like cataract and macular degeneration, so UV protection is a good idea for anyone who spends lots of time outside. However, if you usually wear UV-protective sunglasses, this enhancement might be an unnecessary expense for your eyeglasses.

Scratch protection is recommended for anyone with plastic lenses, especially if you’re rough on your glasses. The coating can crack in extreme temperatures so be careful where you leave your glasses.

An anti-reflective coating on the lenses can reduce glare, reflections and ghost images and can be useful for people with strong prescriptions and people who drive at night. The coating makes your lenses almost invisible in the frames, which makes them a good choice for public speakers. The downside is that the coating is difficult to keep clean, and frequent cleaning can rub it off.

Tints can help light sensitivity, but otherwise they’re purely cosmetic. They add color to your face and tend to hide wrinkles and dark circles under the eyes.