What are photochromic lenses?


Photochromic lenses are one of your options when selecting glasses. This is the type of lens that fades to a darker color when exposed to sunlight or other UV light sources.

Other names for photochromic lenses include:

  • Transition lenses
  • Light adaptive lenses
  • Self-tinting lenses

What are photochromic lenses used for?

Photochromic lenses are ideal for people who have to wear glasses all the time. The two main purposes of photochromic lenses are to protect your eyes from UV rays and to eliminate the need for a pair of prescription sunglasses.

The lenses offer full protection against UVA and UVB rays at all times. This protective function does not depend on whether the lenses are clear or dark at a given time.

UVA and UVB rays are the two types of UV light that can pass through the Earth’s atmosphere. These are the main types you should be concerned about when it comes to your health.

How can UV light damage your eyes?

You are repeatedly exposed to UV light throughout your life, primarily in the form of sunlight. Over the course of your life, UV rays can damage your eyes and the skin around them. This means it’s important to protect your eyes by using products like photochromic lenses.

Types of eye damage that repeated UV exposure can cause include:

  • Cataracts. The lenses of your eyes become cloudy and increasingly cloudy with this condition. Cataracts eventually lead to blindness. You need surgery to treat this condition.
  • Macular degeneration. It is a major cause of blindness in people over the age of 55. It is the result of accumulated eye damage throughout your life. There is currently no cure.
  • Corneal damage. Your cornea is crucial for good vision. UV light waves can particularly damage this part of your eye.
  • Skin damage. The skin surrounding your eye is also vulnerable to UV damage. Examples of skin problems caused by UV include dryness, wrinkles, loss of elasticity and mottled pigmentation.
  • Certain cancer. UV light interferes with the base pairs that make up your DNA. This leads to mutations that could cause cancer. Squamous cell carcinomas are an example of a type of cancer that can invade your eye. Eventually, this type of cancer can lead to the surgical removal of your entire eye.

How do photochromic lenses work?

Photochromic lenses have been around in one form or another since the 1960s. The technology has changed a lot since then, but the fundamentals remain the same.

In general, these lenses work using chemical reactions that are triggered by UV exposure. The result of the chemical reaction is a color change of the lens.

The very first photochromic lenses were made of glass and coated with silver chloride and silver halide, among other molecules. These silver compounds underwent a chemical change when they interacted with UV light waves. The chemical change caused them to turn black. The reaction reversed when the UV light disappeared.

Today, lenses are made from several different materials. Proprietary photochromic dyes are added to these materials in a variety of ways. Molecules of these dyes undergo color changes at different rates when exposed to UV light.

Lenses should darken in proportion to the amount of UV light they receive. This means that the brighter it is in your environment, the darker your lenses will become.

What are photochromic lenses made of?

Nowadays, glass lenses are much less common than new synthetic materials. Most lenses are made from some type of plastic or resin. The reason for this transition is that resins tend to be lighter and stronger than glass. They are also harder to scratch and easier to coat or evenly infuse with the photochromic molecules.

There are many ways to produce resins and infuse them with the necessary colorants. This makes it a more flexible material to work with than glass.

There are a variety of brands of photochromic lenses to choose from. Different brands construct their lenses from different base materials and colorants. So even though all photochromic lenses work pretty much the same way, variations in materials change the characteristics of the lenses, including their rate of color change.

Your lens frames can be made from all types of materials, including metal and plastic.

What types of photochromic lenses can you get?

Today, there is a wide variety of photochromic lenses on the market. You can get them in a range of styles designed to suit your needs. Examples include:

  • Sports glasses. Only certain types of eyewear are safe to use at sporting events. These include polycarbonate and trivex materials. Transition lenses are available in both varieties.
  • Treated lenses. Photochromic lenses do not interfere with the particular types of coatings that people like to have on their lenses. For example, anti-reflective coatings help reduce glare and are good for night driving. Water repellent treatments prevent your lenses from fogging up when you move from a cold outdoor environment to a warm indoor environment.
  • Colored lenses. Traditional photochromic lenses were only available with a gray tint. But normal sunglasses can come in a wide range of colors. Nowadays, you can get brown or green photochromic lenses. The range is still not as wide as for traditional sunglasses, so they may not be available in your favorite color.
  • Bifocalmultifocal and high index. Some lenses are designed to treat specific vision problems. Photochromic lenses are available for most common types of corrective eyewear. For example, bifocal versions help people who have difficulty seeing far and near. High index options are useful for people who need strong prescriptions.

Are photochromic lenses right for you?

Photochromic lenses are not suitable for everyone. There are a few pros and cons to consider before deciding that photochromic lenses are the best choice for your eyewear needs.

Things to keep in mind include:

  • Cost. Photochromic lenses tend to be more expensive than the alternatives. But they are cheaper than buying a separate pair of prescription sunglasses with your normal glasses.
  • Inability to control their transition. You can’t control the lens transition. It just depends on how much UV light they are exposed to. This can be a problem in places with bright fluorescent lights, which can cause your lenses to transition even if you’re indoors. The opposite problem can occur when driving. Windshields are designed to block UV light, so the lenses can’t pass inside a car, even when you want them to.
  • Effects of temperature. Colder temperatures cause some photochromic lenses to transition slower than normal. It can be frustrating in the winter.
  • blue light protection. These lenses offer blue light protection as well as UV protection. This is not true for all lenses. Blue light comes from sources like phone and computer screens and is a common cause of digital eye strain.

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