Photochromic Lenses:
An Overview of Transitions and
Other Photochromic Brands:

Photochromic lenses such as those made by Transitions Optical are clear (or nearly clear) indoors and darken automatically in response to sunlight outdoors. They also protect your eyes from 100 percent of the sun's harmful ultraviolet radiation.

These features make photochromic lenses a great convenience, because they reduce your need to wear prescription sunglasses in most outdoor conditions.

Today's photochromic lenses come in a wide variety of lens materials. So whether you prefer polycarbonate lenses, high-index lenses, or regular plastic or glass lenses, you typically will be able to purchase a photochromic version of your preferred lenses.

Photochromic lenses also are great for kids, who tend to spend more time outdoors than most adults. Experts say the risk for cataracts and other age-related eye problems is associated with a person's lifetime exposure to the sun's UV rays, so protecting your child's eyes early on could pay dividends when he or she is a mature adult.

And remember, polycarbonate is the safest lens material for kids, providing up to 10 times the impact resistance of other lens materials.

Photochromic Brands Including Transitions Lenses;

The technology used for the most popular brands of photochromic lenses today is owned by Transitions Optical. This has led some eye care practitioners and consumers to call all photochromic lenses "transition" lenses.

But though Transitions photochromic lenses outsell other brands, a number of lens manufacturers have their own photochromic lens technology.

Here is a summary of some of the most popular brands of photochromic lenses available today:

ransitions lenses. Transitions lenses are available in nearly every lightweight lens material and lens design, including bifocals andprogressive lenses. The variable tint in Transitions photochromic lenses is available in gray and brown shades.

Transitions Optical partners with other lens manufacturers to make photochromic versions of their lenses. For example, progressive lenses designed by lens manufacturers Essilor, Hoya and Shamir are available with the same Transitions photochromic lens technology.

Transitions lenses are produced in lightweight lens materials only — plastic, polycarbonate, Trivex (similar to polycarbonate) and high-index plastics. They are not available in glass or high-index glass materials.

PhotoGray and PhotoBrown lenses. Corning Inc. created the first mass-produced photochromic lenses in the 1960s, and modern versions of these glass photochromic lenses remain popular today. As their name suggests, Corning's PhotoGray and PhotoBrown lenses are available in variable tints of gray or brown.

Today, Corning also offers a thinner, lighter glass photochromic lens called Thin & Dark. These lenses feature a variable gray tint and are up to 30 percent thinner and lighter than conventional glass photochromic lenses.

The company also has lightweight photochromic lenses called SunSensors. These lenses are available in gray and brown variable tints and are fabricated with mid- and high-index plastic materials.

Like Transitions lenses, Corning's line of photochromic lenses are available in single vision, bifocal, trifocal and progressive lens designs.

ColorMatic photochromic lenses are made by German lens manufacturer Rodenstock. These lightweight lenses are available in variable shades of gray, brown and green.

ColorMatic self-tinting lenses darken quickly outdoors, provide 100 percent UV protection at all times, and return to clear lenses indoors faster than other photochromic lenses, according to Rodenstock. The company also offers ColorMatic IQ Contrast self-tinting photochromic lenses in contrast-enhancing shades of orange and green.

LifeRx photochromic lenses are produced by Vision-Ease Lens. These lenses are made of polycarbonate and are available in variable tints of gray or brown. LifeRx lenses darken in less than one minute and the photochromic dye is formulated to fade back faster indoors than leading photochromic lenses, according to the company.

In 2011, German lens manufacturer Carl Zeiss Vision introduced PhotoFusion self-tinting photochromic lenses. PhotoFusion lenses provide 100 percent UV protection and are available in a neutral gray tint for accurate color vision in all lighting conditions. The lenses darken up to 20 percent faster and lighten indoors up to twice as fast as previous Zeiss photochromic lenses, according to the company.

Signet Armorlite offers its PhotoViews photochromic lenses in a wide variety of standard plastic lens designs, including single vision, bifocal, trifocal and Kodak brand progressive lenses. PhotoViews lenses provide 100 percent UV protection and are available in gray and brown tints (gray only in trifocals).

Photochromic Sunglasses:

One limitation of Transitions and other photochromic lenses is that they don't darken adequately inside a vehicle for driving in sunny conditions. This is because they require exposure to the sun's invisible UV rays to activate the darkening process, and most car and truck windshields block UV radiation.

Fasano sunglasses, by Serengeti Sport, have photochromic lenses with an anti-glare coating.

To overcome this problem, some lens manufacturers have introduced "sun" photochromic lenses that are designed primarily for outdoor wear and daylight driving. These lenses have a mild tint for driving and darken further when directly exposed to sunlight.

Currently, two leading brands of photochromic sunglass lenses are:

Transitions XTRActive. These photochromic lenses from Transitions Optical are darker than regular Transitions lenses and are designed for wearers who prefer a slight tint indoors and very dark lenses outdoors. Transitions XTRAcitve lenses also darken moderately inside a car or truck, according to the company.

Transitions XTRActive lenses currently are available in polycarbonate, Trivex and 1.67 high-index plastic lens materials in single vision and progressive lens designs.

Drivewear lenses are photochromic polarized sunglasses developed by Younger Optics in partnership with Transitions Optical. The lenses are capable of sensing and reacting to varying light conditions both outdoors and behind the windshield of a car or truck, according to Younger Optics.

With their combination of photochromic and polarization technologies, Drivewear lenses reduce glare and maximize visual acuity in bright light conditions, the company says. Drivewear lenses currently are available in plastic and polycarbonate lens materials in single vision, bifocal and progressive lens designs.

Medical Applications of Photochromic Lenses:

In addition to adjusting automatically to different lighting conditions, some photochromic lenses also have medical applications.

Corning's CPF family of glass photochromic lenses has specially selected red colors. These lenses sometimes are used to enhance the vision of patients who have various eye pathologies, including macular degeneration. Doctors who specialize in low vision are familiar with these lenses and can determine if they will be effective for specific vision problems.

Non-Photochromic Tinted Lenses:

Alternatives to photochromic lenses for improving visual comfort are lenses with tints that remain constant at all times.

Tints of virtually any color can be applied to eyeglass lenses. Lighter, fashion tints are used primarily for cosmetic purposes to enhance a wearer's looks. Darker tints allow the wearer to use the lenses assunglasses.

Color can be added to a lens as a solid tint, where the entire lens has the same color density, or as a gradient tint, where the color density is darkest at the top of the lens and gradually fades to clear or nearly clear at the bottom.

Different colors can be applied to lenses for different purposes:

Yellow often is added to a lens to enhance contrast, especially in overcast conditions, making it a popular tint for hunters who desire "shooting glasses."

Green, or its cousin G-15 (the classic color of lenses in Ray-Ban sunglasses), is sometimes used as a sunglass tint, though brown and gray are the most popular sun shades.

Red is a bold fashion color and also is popular among people who enjoy seeing the world through "rose-colored glasses."