Transition lenses, also known as photochromic, are eyeglass lenses that are clear indoors and change to dark in sunlight, according to All About Vision. The transition lens is available in a variety of shades ranging from gray to green. Though transition lenses darken in response to sunlight, it is possible to make them darker.

Ask for transition lenses that are XTRAactive or Drivewear. These lenses, according to Transitions Optical Incorporated, are darker than original transition lenses. These photochromic lenses are extremely dark outdoors and are compatible with many frame brands and styles.

Go outdoors in the sun to make your transition lenses the darkest shade possible. Transitions Optical Incorporated states that transition lenses are treated to block harmful UVA and UVB rays from the sun.

Find darker transition lenses from ophthalmologists, optometrists, opticians and optical retail chains, advises the Federal Trade Commission.