What are photochromic lenses and how do they work?​

Photochromic lenses also called light-adaptive lenses, or variable-tint lenses, look like regular clear lenses when indoors but automatically darken when exposed to sunlight. Ultraviolet (UV) rays from the sun affect the molecules in the photochromic lenses causing the lenses to change colour. Photochromic lenses may darken even on overcast days as UV rays still penetrate the clouds. These lenses usually would not darken inside a vehicle as the windshield glass blocks out most of the sun’s UV rays.

What are the benefits of photochromic lenses?

  1. Photochromic lenses help to reduce eye strain and decrease the risk of eye damage such as cataracts later in life by blocking up to 100% of the sun’s harmful ultraviolet light.
  2. With photochromic glasses, this reduces the hassle of needing to bring a pair of sunglasses whenever you are going out and switch between the two when travelling to different environments.
  3. Although photochromic glasses can be more expensive than ordinary prescription glasses, it may be a cost-effective option as you only have to pay for 1 pair of eyewear.

How does UV rays affect eye health?

Extended exposure to UV rays can harm your vision and increase the risk of several eye diseases in the long term. UV rays can cause the cornea (front of the eye) to become inflamed or burned. Additionally, it can also lead to skin cancer around eyelids, cataracts (clouding of the lens of the eye) and pterygium (tissue growth on the surface of the eye) which can impair vision.

One of the most popular brands of photochromic lenses is Transitions® lenses.

What are the benefits of Transitions® lenses?

  •   Automatically adapt to the perfect shade based on the changing light conditions, enabling you to see clearly with just the right amount of light
  •   Blocks 100% of UV rays and protect against harmful blue light indoors and outdoors
  •   Designed to be worn all day, everyday
  •   Anyone can wear Transitions® lenses as there are options for every lifestyle and every age, from kids to adults and elderly
  • Designed to fit virtually every frame, style, size and prescription

How long do photochromic lenses usually last?

Plastic photochromic lenses usually last about 2.5 to 3 years which is longer than the typical amount of time one changes his/her glasses due to changes in one’s prescription. In contrast, glass photochromic lenses would never lose their ability to block UV rays. In fact, its function would improve with more usage.


Sources

Essilor

http://www.x-celoptical.com/faq.php

https://www.cancer.org/cancer/cancer-causes/radiation-exposure/uv-radiation.html#:~:text=UV%20rays%2C%20either%20from%20the,can%20also%20cause%20eye%20problems.

https://www.northwoodvision.com/6-things-you-should-know-about-uv-radiation-and-your-eyes/

https://www.cancer.org/cancer/cancer-causes/radiation-exposure/uv-radiation.html#:~:text=UV%20rays%2C%20either%20from%20the,can%20also%20cause%20eye%20problems.