The Complete Guide to Photochromic Eyeglass Lenses

Photochromic eyeglass lenses are innovative eyeglass lenses that automatically darken when exposed to ultraviolet (UV) light. Since their invention in the 1960s by Corning Glass Works, these lenses have continued advancing with new generations featuring improved performance.

In this article, you will learn about the function of photochromic lenses, the various types available, their benefits, factors to consider when selecting a pair, and proper care.

With their convenient light-adaptivity, photochromic eyeglass lenses promise to only increase in popularity. This guide serves as a comprehensive reference to these cleverly engineered vision products.

History of Photochromic Eyeglass Lenses

William H. Armistead and Stanley Donald Stookey at Corning Glass Works Inc. are credited with developing these lenses. The technology behind photochromic lenses involves embedding microcrystalline silver halides, usually silver chloride, into a glass substrate.

These lenses darken when exposed to sunlight due to the photochromic properties of the embedded materials​​​​.

The first commercial photochromic lenses were introduced by Corning Glass Works in 1964. Initially, these lenses were heavy, thick, and not dark enough to function effectively as sunwear.

Over time, advancements have been made to improve the comfort and functionality of these lenses. Corning also introduced an organic photochromic line of lenses, evolving from the initial glass lenses that used silver dispersed throughout the medium​​​​​​.

Market of Photochromic Eyeglass Lenses

The photochromic lens market has grown significantly and is expected to continue expanding. The market size was valued at approximately $6.88 billion in 2023 and is projected to grow to $9.13 billion by 2028, with a compound annual growth rate (CAGR) of 5.81% during this period. Another estimate suggests a growth from $7.34 billion in 2023 to $11 billion by 2028, at a CAGR of 8.44%​​​​.

Additionally, reports indicate that the market expanded from $5.82 billion in 2021 to an estimated $8.79 billion by 2028, reflecting a CAGR of approximately 7.10%​​​​. Looking further ahead, projections expect the market to reach $10.7 billion by 2032, with a growth rate of 5.3% during 2024-2032​​.

How Photochromic Eyeglass Lenses Work

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Source: AllAboutVision

The functioning of photochromic eyeglass lenses involves a complex chemical process sensitive to UV light:

• Chemical Composition: These lenses contain molecules like silver chloride or other silver halides, which are transparent under normal artificial lighting. These molecules undergo a chemical change in the presence of UV rays, typically from sunlight.
• Darkening in Sunlight: The lenses darken due to the molecular change in the embedded chemicals when exposed to UV light. This happens as electrons interact with the silver ions, forming visible elemental silver.
• Reversal in Shade: The lenses reverse the reaction once removed from UV exposure. The silver returns to its original ionic state, making the lenses clear again.
• Transition Time: The darkening of the lenses occurs in less than a minute, with further darkening over the next fifteen minutes. When removed from UV light, the lenses start clearing within two minutes and return to their original state in about fifteen minutes.
• Temperature Dependency: The process of returning to a clear state is temperature-dependent. At higher temperatures, the lenses won't darken as much, while in cold conditions, they get darker and take longer to clear up when back indoors.

Types of Photochromic Eyeglass Lenses

Photochromic eyeglass lenses come in various types, each with unique features:

1. Transitions Gen 8 Lenses: Introduced in 2019, these lenses protect against indoor and outdoor light, changing from dark to clear more quickly than others. They can achieve significant darkness outdoors (up to category 3) based on UV light intensity and temperature.
2. Transitions Vantage: These lenses slightly darken indoors and polarize outdoors for comfort and sharper vision, blocking reflective glare from surfaces like roads and water
3. Transitions XTRActive: Designed for those sensitive to indoor light and seeking a darker shade outdoors, these lenses block up to 34% harmful blue light indoors and 90% outdoors. They are suitable for driving as they activate fast and behind the windshield.
4. LifeRx Photochromic Lenses: Made from polycarbonate, these lenses darken quickly (within 60 seconds) and provide 100% UVA and UVB protection
5. Sensity Photochromic Lenses: Introduced by Hoya Vision Care in 2016, these lenses adjust tints based on UV, climate, and temperature. They come in various colors and materials, with options like mirror coatings for a trendy look.
6. ColorMatic IQ Sun 2: These German-made lenses offer comfortable UV and glare-free vision, with a basic tint of 40% in low light and darkening in strong sunlight. They are available in tints like chocolate brown, pure gray, and racing green.
7. ZEISS PhotoFusion Lenses: Developed by Carl Zeiss Vision, these lenses provide accurate color vision in different light conditions and come in colors like brown, gray, blue, and pioneer green. New versions darken up to 60% faster than previous ones.
8. PhotoBrown and PhotoGrey Lenses: Developed by Corning, these glass lenses are scratch-resistant and feature a silver chloride compound for color changes. They are designed to be lighter and thinner than conventional lenses.
9. SunSensors Lenses: Initially made by Corning and later acquired by Mitsui Chemicals, these plastic lenses darken slowly and maintain their tint even indoors

Benefits of Photochromic EyeglassLenses

The optometry community recommends photochromic eyeglass lenses to minimize UV exposure and eye discomfort due to changing light conditions. A study found that 30% of respondents preferred photochromic eyeglass lenses for their automatic tint change. Also, sales of these lenses saw an 8.5% increase from 2014 to 2015, adding $205 million to U.S. practices specializing in photochromic eyeglass lenses.

These lenses' popularity stems from their comprehensive benefits, including:

• UV Ray Protection: Photochromic lenses shield the eyes from harmful UV rays, which prevents eye problems like cataracts and macular degeneration. By blocking UV radiation, these lenses reduce risks associated with long-term sun exposure​​​​.
• Convenience: They eliminate the need for separate prescription glasses and sunglasses, transitioning automatically between different lighting conditions. This feature offers significant convenience for users who frequently move between indoor and outdoor environments​​.
• Reduced Eye Strain: By automatically adjusting tint levels in response to light changes, photochromic lenses help reduce eye strain caused by sudden shifts in brightness. They offer a smoother transition for the eyes when moving from low to bright light or vice versa​​.
• Outdoor Versatility: Especially beneficial for outdoor activities, these lenses provide visibility and color contrast when needed. For drivers, they reduce sun and headlight glare, enhancing safety and vision clarity​​.

Choosing Photochromic Eyeglass Lenses

When selecting photochromic lenses, several key factors should be considered to ensure the best choice for your needs. Here are the following:

• Lens Material: The material of the lens impacts optical performance, impact rating, and weight. Common materials for photochromic lenses include polycarbonate and TrivexTM, which are suitable for most prescriptions.
• Activation Speed: This refers to how quickly the lenses darken when exposed to UV radiation. If you're involved in high-energy activities like skiing or snowboarding, you'll need lenses that can rapidly adjust to changes in brightness.
• Darkness Levels: Different photochromic lenses have varying darkness ranges. Select lenses that match your preference and the typical lighting scenarios you encounter.
• Lens Color: Photochromic lenses are available in various colors, each offering different benefits. For example, brown lenses enhance depth perception and are ideal for outdoor activities, while grey lenses maintain realistic color perception.
• UV Protection: One of the most essential benefits of photochromic lenses is their ability to block dangerous UV rays. Ensure that the lenses you choose provide 100% UV protection.
• Style and Fashion: With various fashionable styles available, you can choose photochromic lenses that complement your look. Whether you prefer classic or trendy styles, there are plenty of options to match your fashion sense.
• Care and Maintenance: Proper maintenance is crucial to extend the lifespan of your photochromic lenses. Avoid harsh chemicals and rough objects to prevent scratches, and always store the glasses in a case when not in use.
• Color Options: Consider which lens color suits your activities and fashion preferences, as they come in shades from gray to brown and even green.
• Fade-back Speed: Some lenses revert to clear faster than others. Think about how quickly you need your lenses to return to their original state.
• Personal Preferences: Your preferences regarding lens thickness, curvature, and material are important. Discuss these aspects with your eye care professional to ensure your lenses meet your needs.

Care and Maintenance

To maintain photochromic eyeglass lenses effectively, follow these guidelines:

• Cleaning: Use lukewarm water or designated lens cleaning solutions with a soft microfiber cloth to clean the lenses. Avoid harsh cleaners like bleach or alcohol to prevent damage to the special coatings.
• Storage and Handling: Store lenses in protective hard cases to prevent damage. Avoid placing glasses upside down on hard surfaces. Limit exposure to light when not wearing them for consistent photochromic performance.
• Lifespan: Plastic photochromic lenses maintain their light-adaptive properties with regular wear for one to two years. Consider replacement if performance declines or inconsistencies arise.
• Performance Factors: Extreme cold can slow photochromic reactions in older lenses, while hot vehicle interiors can accelerate chemical breakdown. Scratches, solvents, and damage to the lens surface disrupt uniform light transmission.

Wrap-Up

Since their inception in the 1960s, photochromic eyeglass lenses have rapidly evolved from a novel innovation into a staple vision product relied upon by millions globally. The photochromic lens market continues to expand exponentially as technology improvements meet growing consumer demand for convenient, automatic light-adaptivity.

With advanced UV protection, glare reduction, and light management capabilities, today’s photochromic lenses enable customized optical experiences suitable for diverse lifestyles and activities. Continued research foreshadows further performance enhancements on the horizon.

For those seeking the benefits of hands-free visibility adjustments, quality photochromic eyeglass lenses are now more accessible in diverse materials, activation speeds, shade ranges, and stylish designs to match personal preferences. After six decades, photochromic technology has become a mainstay that will only become more advanced and ubiquitous in the coming years.

Can I use photochromic lenses as sunglasses to protect my eyes from UV rays?

Yes, photochromic lenses provide UV protection by darkening in response to UV light, helping to shield your eyes from harmful UV radiation.

Can I wear photochromic lenses for sports or outdoor activities?

Photochromic lenses are suitable for outdoor activities and sports, providing clear and shaded vision.

Are photochromic lenses suitable for children and teenagers?

Yes, photochromic lenses can be a good option for children and teenagers who need vision correction and UV protection. They offer convenience and protection for active lifestyles.

Can I wear photochromic lenses if I have a specific eye condition, such as cataracts or glaucoma?

Photochromic lenses are generally safe for individuals with eye conditions like cataracts or glaucoma. Still, it's essential to consult your eye doctor to ensure they suit your specific needs.

Are photochromic lenses suitable for driving?

Yes, photochromic lenses are generally suitable for driving as they can adapt to changing light conditions, providing clear vision in various lighting situations.