Light-adaptive photochromic lenses for glasses and sunglasses

The photochromic lens is a spectacle lens that is clear (or nearly clear) indoors and darkens automatically when exposed to sunlight, and is also known as a light-adaptive lens or a variable tint lens.

In the UK, Transitions lenses are the most popular brand of photochromic lenses. Because of this, some people – including some eye care practitioners – refer to photochromic lenses as “transition lenses” or “transition lenses.” However, there are also other brands of photochromic lenses available.

Photochromic lenses darken when exposed to ultraviolet radiation from the sun. Because ultraviolet rays penetrate clouds, photochromic lenses darken both on sunny and overcast days.

Due to the fact that most UV rays are reflected by the windscreen glass, photochromic lenses do not typically darken inside a vehicle. Several photochromic lenses can now be activated with both UV and visible light, resulting in some darkening behind the windscreen. Consult your optician for details.

In addition to being available in nearly all lens materials and designs, photochromic lenses are able to shield your eyes from 100 percent of the sun’s harmful UVA and UVB rays.

The lifetime exposure of an individual to sunlight and UV radiation has been linked to cataracts later in life, so it is advisable to consider photochromic lenses for children as well as adults’ spectacles. It provides up to ten times the impact resistance of other lens materials, making polycarbonate the safest lens material for children.

By adding an anti-reflective coating to photochromic lenses, their performance is further enhanced. It allows more light to pass through photochromic lenses, resulting in sharper vision in low-light conditions (such as driving at night) and eliminating bothersome reflections from the back of the lenses in bright conditions.

In spite of the fact that photochromic lenses are more expensive than clear spectacle lenses, they provide the convenience of reducing the need to carry prescription sunglasses with you wherever you go.

Brands of photochromic lenses

There are several popular brands of photochromic lenses available in the UK, including:

Transitions Signature
Transitions Signature lenses with Chromea7 technology represent the latest advancement in Transitions adaptive lenses. They are available in grey, brown, and graphite green. According to the company, the lenses are almost completely clear indoors but are more responsive to sunlight, so they appear darker when necessary. Of all Transitions products, Transitions Signature lenses fade back to clear the fastest.

Transitions XTRActive
 These lenses have been developed to provide wearers with a darker lens when driving or outdoors who are light sensitive. The Transitions XTRActive lenses provide a slight tint in the interiors of the lenses to ensure eye comfort under harsh lighting conditions (fluorescent lights, digital devices). Additionally, they are available in gray, brown and graphite green tints and can also be activated behind the windscreen of a car.

Transitions Style Colours
 Transitions Style Colours lenses are available in four new vibrant fashion colours, allowing you to combine lenses and frames to create the perfect look. They are available in vintage amber, striking amethyst, cool sapphire and versatile emerald.

Sensity (Hoya Vision Care)
Introduced in 2014, Hoya’s Sensity photochromic lenses feature patented technology that ensures the lenses perform consistently in varied climates and temperatures, according to Hoya Vision Care. A number of lens designs, lens materials, and anti-reflective coatings are available for Sensity lenses, including grey, emerald green, and contrast-enhancing brown.

PhotoFusion (Carl Zeiss Vision)
Made in Germany, PhotoFusion lenses are available in five colors for accurate colour vision in all lighting conditions. Zeiss photochromic lenses darken and light indoors 20 percent faster than previous models.

ColorMatic (Rodenstock)
 Also made in Germany, Rodenstock’s ColorMatic lenses are offered in grey, brown and green photochromic tints, as well as ColorMatic IQ Contrast lenses in orange and green contrast-enhancing shades.

PhotoView (Signet Armorlite)
 Made of lightweight plastic and polycarbonate, PhotoView lenses come in gray and brown photochromic tints and are available in a variety of designs, including Kodak progressive lenses.

Photochromic lenses and blue light

Aside from protecting your eyes from glare outdoors, photochromic lenses offer another important benefit: they shield your eyes from harmful blue light.

As a result of blue light exposure, the retina is stressed and oxidative stress occurs. In fact, long-term exposure to harmful blue light from sunlight as well as computer screens, smartphones and other digital devices may increase a person’s risk of developing macular degeneration and other eye disorders.

A photochromic lens can be helpful. For example:

• Photochromic lenses from Transitions block 1.4 times more harmful blue light indoors than basic clear lenses, and they filter over 8 times more harmful blue light outdoors.

• Compared to clear lenses, Transitions XTRActive photochromic lenses block at least two times more harmful blue light indoors and eight times more harmful blue light outdoors.

Consult your optician to discuss your blue light exposure risks and the type and brand of photochromic lenses that will meet your specific requirements.