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What are photochromic lenses (transition lenses)?

Lensmart 2022-02-21 15:57:25

For some people, wearing glasses isn’t just to complete an outfit or make a fashion statement—it's necessary to correct vision errors. However, using prescription glasses outdoors can be uncomfortable especially if the sun is shining in full force. You’d have to switch between this pair and sunglasses to shield your eyes from harsh sun rays, or you could use photochromic or transition lenses instead.


What are photochromic lenses (transition lenses)?

Photochromic lens may sound fancy and complicated but it’s quite easy to understand. This type of lens, often called transition lens, gradually shifts from clear to dark with exposure to ultraviolet (UV) rays. These glasses are also referred to as light-responsive, light-intelligent, or adaptive lenses, which is a nod to this distinctive feature.

These lenses work like magic in that it transitions as soon as your feet step on the outdoors, whether the sky is overcast or clear. Scientifically, the lenses alter their darkness via a chemical coating that reacts to UV light, accounting for the changes in the tint.

The first photochromic for glass lenses were introduced in 1966 and has since undergone improvements in material, design, and technology to be what it is today. These lenses now have impressive light response mechanisms and are lightweight in form, giving the wearer additional comfort and outstanding style.


photochromic lenses


How do photochromic lenses work?

Decades ago, photochromic glass lenses only came in gray color and tended to darken quickly if one lens was thicker than another. The light-adaptive technology was short-lived, making the lenses appear darker indoors.

Transition lenses today are available in many lens colors and use materials that enhance the light-intelligent function. The lenses are made with proprietary dyes that chemically change when UV rays hit the lens.

Glass photochromic lenses are embedded with silver halides to achieve the reversible darkening process, while polycarbonate and plastic transition lenses are coated with organic photochromic molecules like spiroxamine and naphthopyran.

How do these lenses darken outside but not indoors? Artificial or room light does not contain short wavelength UV light present in sunlight, which is what the transition lens needs to activate the darkening effect. The photochromic performance is affected by cold weather, which slows down the reaction to UV rays, taking a longer time to darken or lighten.


Is photochromic lens good for the eyes?

Transition lenses are highly recommended by eye doctors because they are one of the best defenses against hazardous ultraviolet light. It can offer the best of both worlds: vision correction and UV protection in one single frame.

Experts also believe that photochromic lenses help adults and children avoid developing eye problems such as cataract later in life. This condition is linked with constant exposure to UV radiation and sunlight, which the transition lens is designed to block.

This type of lens is good for your eyes because it can effectively prevent eye strain, premature aging, and vision damage due to harmful light rays.

 

Pros and cons of photochromic lenses

Is the transition lens worth using? You can weigh these pros and cons before figuring out if this type of lens is suitable for you.

Pros:

1. Cost effectiveness. Some people assume that the photochromic lenses are an impractical expense because they can cost more than traditional glasses. However, think about it: once you own transition lenses, you don’t have to buy two sets of frames for your prescription and normal glasses, making it the most cost-effective option.

2. Comfort and protection. These lenses filter a great deal of harsh UV and UVB rays from sunlight, keeping your eyes healthy and happy.

3. Convenience. Since these lenses are a two-in-one option, you don't have to carry two pairs of glasses wherever you go. It also eliminates the hassle of having to switch what you're wearing to fit the setting since you can use these glasses for indoors and outdoors.

4. Lesser risk of losing glasses. You are more likely to lose your glasses if you are switching from your prescription to sunglasses when going outside. It’s easier to keep track of your specs when there’s only one pair to worry about.

5. Style. You'll be astounded by the sheer number of choices to have when selecting transitional lenses. There are many designs, tints, and shades that suit every type of fashion, giving you the freedom to have eyewear that fits your style.

Cons:

1. Decreased performance in cold weather. Photochromic lenses take longer to transition from clear to dark and vice versa during the cold months.

2. Brand discrepancies. There's no standard to the transitional lens because every brand creates different reaction times and levels of darkness, making it tricky for you to decide which brand works best for you.

3. Ineffectiveness in night driving. If you’re driving along the highway at night, you cannot rely on your light-adaptive lenses to effectively protect you from glaring headlights. Most of these glasses only react to UV rays emitted by the sun.

4. May not be polarized. Not all transition glasses are polarized, which means that you might not be fully protected from very harsh glares in various settings like water, pavement, and snow.

 

How can you find the best photochromic lenses?

Evaluating your daily lifestyle and activities can help you decide which transition lenses will meet your needs. For example, if you drive frequently to and from work, you must have glasses that are designed to darken even behind the windshield.

These days, you can also opt for transitional contact lenses over traditional glass lenses, allowing you to enjoy outdoor activities without worrying that your glasses will fall off. Conversely, if you work in front of a computer all day, you should pick photochromic spectacles that have added blue light protection.

When choosing eyewear, it’s also crucial that you consider your facial structure to ensure that the frame enhances your look. If you have a square-shaped face, round glasses can soften your strong jawline. If your face is more on the diamond-shaped side, you can wear cat eye glasses that flatter your temples and balance your features.

It’s best to talk to your eye care professional regarding the right transition lenses for you because they can recommend tested and proven eyewear that fits your preference and personality.



More about glasses lenses:

The advantages and disadvantages of high index lenses

Transition lenses problems you should know

What are advantages and disadvantages of progressive lenses

What are the advantages and disadvantages of bifocal lenses