When it comes to selecting eyeglasses or sunglasses, there are a lot of options to choose from. Two popular choices for lenses are polarized and photochromic lenses. Polarized lenses are designed to reduce glare, while photochromic lenses are designed to darken when exposed to UV light.
Both types of lenses have unique features and benefits, but which one is right for you? In this blog post, we'll dive into the differences between polarized lenses and photochromic lenses, and help you determine which one is the best fit for your needs.
Polarized Lenses Manage Reflected Light
Polarized lenses are Sunglass Lenses that reduce or eliminate reflected light. Reflected light is the most uncomfortable and distracting light we see outdoors. Light reflecting off sand, water, or snow is added to the natural light in the sunshine until we experience an intolerable level of brightness. Light reflecting off car windshields does the same when we are driving. Polarized lenses manage all this reflected light making your new Polarized Prescription Sunglasses as soothing and comfortable as they can be.
Light travels in a spiral. Initially, all the light is spiraling in the same direction, but when it strikes a surface, the light spirals in the opposite direction when it reflects back. This mixed light gives a confusing message to the visual system that we perceive as glare.
Polarized lenses allow only the normal light to pass through and not the light spiraling in the opposite direction, minimizing the experience of glare. This is very soothing for the eyes and allows the wearer to see past the reflections on the surface of the water or on a windshield, for example. This is one of the main reasons why polarized lenses are very popular among drivers, boaters, and anglers.
Expert Tip:
Digital screens emit polarized light, so polarized sunglasses block out parts of the image and are not ideal for digital devices. Also, polarized lenses eliminate reflections from the surface of a puddle on the road, creating a risk for motorcyclists and cyclists.
Elite golfers who judge the lay of the green by the reflection of the surface of the blades of grass will notice that this is more difficult wearing polarized lenses that eliminate these reflections. Lastly, the lamination required to make airplane windows strong enough to withstand changes in atmospheric pressure at altitude creates a partial, uneven polarization of light passing through the windows of aircraft. Also, the light reflected from another aircraft in a “see and avoid” situation will be the first indication of other air traffic in proximity.
For these reasons, and to see the polarized instruments in the cockpit, Polarized Lenses should not be used by pilots.
Photochromic Lenses Lighten and Darken According to Brightness
Photochromic lenses, also known as adaptive lenses, are a type of eyeglass lenses that automatically adjust their tint in response to changing light conditions. When exposed to ultraviolet (UV) light, such as sunlight, the lenses darken to provide protection and reduce glare. When indoors or away from UV light, the lenses return to their clear state.
How do photochromic lenses work?
Sunlight contains lots of energy. Ultraviolet light in the sunshine has enough energy to cause a sunburn! Photochromic lenses take advantage of this energy in UV light to cause a change in the lens’ transmission properties.
When the UV light strikes the photochromic molecules in the lens, the photochromic molecule changes shape, like a shutter closing on the blinds in the windows of your home. This decreases the amount of light that can pass through the photochromic lenses and they darken like a sunglass.
When you wear your photochromic lenses indoors, where there is no ultraviolet light, the photochromic molecules in your lenses revert back to their neutral shape, and light can pass through again with 100% transmission.
Why don’t my photochromic lenses work anymore?
Over time, the photochromic molecules in your lenses degrade and lose their ability to change. Glass photochromic lenses lose their ability to lighten, and plastic photochromic lenses lose their ability to darken. This happens to all photochromic lenses after about 18 months to two years of use.
What’s the difference between photochromic lenses and Transitions brand lenses?
Just like there are different modes of vehicular travel, there are different types of eyeglass lenses. Cars and trucks are different ways of getting around, just like polarized lenses and photochromic lenses are different ways of getting dark glasses. Toyota Prius and Ford Mustang are two car brands, just like Transitions is a brand of photochromic lens.
What’s the difference between Transitions, Photofusion, Sensity, and Photogrey brand lenses?
Transitions, Photofusion and Sensity are all plastic, photochromic lenses from different manufacturers. Photogrey is a glass photochromic brand of eyeglass lenses.
Photochromic lenses are popular because they offer the convenience of combining both prescription eyeglasses and sunglasses into a single pair. Photochromic lenses provide continuous comfort and protection by adapting to different lighting environments, making them a practical choice for those with changing visual needs throughout the day.
Expert Tip:
Remember that all photochromic lenses need to be exposed to ultraviolet light to trigger the change from clear to dark. Your vehicle windows block UV light to protect passengers and drivers from the risk of skin cancer and sunburn due to UV light exposure when driving.
This means that your photochromic lenses will not work well in the cab of your vehicle. If you need your glasses to be dark when driving, a separate pair of Polarized sunglasses may be the better choice for you.