In Part 2 of my “Geek Chic Eyewear” series I will delve into the various len materials and designs. While frames (covered in Part 1) play a significant role in the aesthetics of your eyewear, the quality of the lenses is paramount. Poor-quality lenses can severely detract from the overall functionality and satisfaction of your glasses, regardless of how stylish the frames may be.
This post will explore topics such as single vision lenses, progressive lenses, lens tints, lens coatings, and computer glasses. It will be more technical than Part 1, which focused on eyewear brands and material quality. Prepare to engage with detailed insights and technical information on optimizing your eyewear.Â
Disclaimer: I’m not a medical professional, optometrist, or optician. This post is not sponsored by any company, and there are no affiliate links. I have no financial interest or ties to any content I’ve linked to. Always consult a qualified eye care professional to help you find your perfect pair of glasses.Â
I am a happy customer of the Spectacle Factory (Preston, UK) and Laguna Eyes (Laguna Beach, CA), but received no discount or special treatment from either office. This series is about sharing my personal experience and research not promoting any one brand, person, or eyecare office.Â
Series Overview
This series of four posts will cover a wide range of topics, covering various aspect how to get your perfect pair of glasses. These posts are focused on the tech angle of eyewear, and are not about fashion or what’s on trend for 2025.Â
Topics in this series include:
Part 1: A Comprehensive Guide to Frame Selection
- The Elephant in the Optometrist’s Office
- Frame Materials
- Cellulose Acetate
- Titanium
- Frame Brands – Quiet Luxury vs. Trash
- The Epitome of Trash
- Quiet Luxury – Wisely Spending your Money
- Best Acetate Frames in the World
- Best Titanium Frames in the World
Part 2: Understanding Lens Materials and Designs (This Post)
- Lens Choices Galore – An Overview
- Two Key Lens Properties Explained
- Abbe Value and Refractive Index
- Lens Materials
- Lens Design
- Zeiss ClearView Lenses
- Zeiss SmartLife Lenses
- Zeiss DriveSafe Lenses
- Progressive (Varifocal) Lenses
- Reading vs. Computer Glasses
- Lens Tints Galore
- Sunglasses: PhotoFusion X vs. AdaptiveSun
- Lens Coatings
- Blue Light – To Block or Not to Block?
Part 3: Optometry Tools, Eye Health and Insurance
- Zeiss Optometry Equipment
- i.Profiler Plus
- VISUPHOR 500
- VISUFIT 1000
- i.Terminal 2
- Eye Health
- LifeMeter
- Eye Supplements
- optomap
- Visionix Optovue Solix
- Managing Vision Expenses
- Insurance Tips
- HSA/FSA Savings
- Medical Accommodation for Computer Glasses
- Finding a Zeiss Specialist
- Questions to ask your Optometry Office
- Caring for your Eyewear
- My Optometrist Saga
- My Eyewear Collection
- Buying Reykjavik Eyes Frames in the US
- How to Read Your Prescription
Over the last couple of years a great source of eyewear information has been Robert over at the Spectacle Factory YouTube channel. Robert is a highly skilled Optician in the UK, and is a fountain of knowledge when it comes to eyewear brands, lens design, styling, and much more. He is very passionate about helping people find the perfect pair of glasses, and that shows through in all his videos.Â
In September 2023 I made a personal visit to the Spectacle Factory in the UK and got two pairs of custom sunglasses. Yes, I traveled from California to the UK for custom eyewear. More on that later!Â
Lens Choices Galore - An Overview
A few years ago, I believed that obtaining a good vision prescription from an eye doctor was the only step needed to ensure perfect glasses. It seemed straightforward: get the prescription, choose the frame, order the glasses, and enjoy clear vision. However, this assumption is VERY incorrect. The reality is that numerous lens options can significantly impact your visual experience. Unfortunately, some opticians may take a one-size-fits-all approach, assuming customers won’t notice or question their choices.
This post aims to equip you with the knowledge necessary to make informed decisions about your eyewear. With this information, you’ll be able to engage confidently with your optician and ensure you select the lenses that best meet your needs.
There are a number of lens manufacturers and not all lenses are of equal quality. Check out Robert’s video on his rating of various lens brands. He rates them from “VHS” to “4K”.Â
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Robert’s Rating:Â
- VHS: Pentax, Kodak
- SD: Seiko, Nikon
- HD: Rodenstock, IoT, Maui Jim
- 4K: Zeiss, Essilor, Hoya, Shamir
Spoiler: Zeiss arguably produces the best optical and sunglass lenses in the world. And, they are in no way associated with EssilorLuxxotica (see Part 1 of this series why you should avoid them like the plague), which is a big win.Â
For a good overview of all Zeiss lenses, tints and coatings available, check out Robert’s video below. This video is from 2024 and covers all the latest Zeiss advances. My post focuses on the Zeiss product line, so watching this video will help you better understand the rest of the content in this post.
Two Key Lens Properties Explained
When selecting eyewear, understanding the relationship between the Abbe value and the lens refractive index is essential for informed decisions affecting visual clarity and comfort.
The refractive index determines how much a lens can bend light, influencing its thickness and weight. Higher refractive index materials are lighter and thinner for high prescriptions but often have a lower Abbe value. This measures the material’s ability to minimize chromatic aberration—distortions where colors blur or fringe. The next sections cover these topics in more detail.
What's the Abbe Value?
The Abbe value is a measure of a lens material’s dispersion, which refers to how much the material spreads out different wavelengths of light. For eyewear the Abbe value is crucial because it affects the clarity and quality of vision through the lenses. The Abbe value takes into consideration yellow, blue-green, and red wavelengths.Â
Materials with a low Abbe value (below 40) tend to cause more chromatic aberration, where different colors of light are refracted at slightly different angles. This can result in color fringing and blurred vision, especially noticeable in high-prescription lenses or when looking through the edges of the lens. High Abbe values (above 45) indicate less dispersion and therefore clearer vision with minimal chromatic aberration.
For eyewear, choosing a lens material with a higher Abbe value generally leads to better visual comfort and clarity. Common lens materials like polycarbonate have a lower Abbe value (around 30), while CR-39 plastic and glass have higher values (around 58 and 59, respectively). However, the choice of lens material must also consider other factors such as weight, impact resistance, and thickness, balancing the Abbe value with practical needs. Keep reading for more about lens materials!Â
What's the Refractive Index?
The refractive index of a lens material in eyewear measures how much the material bends light. A higher refractive index means the lens can bend light more efficiently, allowing for thinner lenses to achieve the same prescription strength. This is particularly beneficial for high-prescription lenses, as it reduces thickness and weight, improving comfort and aesthetics.
Common lens materials range from 1.50 (standard plastic) to 1.74 (high-index plastic). While higher refractive index lenses are thinner and lighter, they may have lower Abbe values, potentially leading to more chromatic aberration. Balancing refractive index with visual clarity is key in lens selection.
You can see in the diagram below how the thickness of your lens is impacted by the various refractive index of the lens material you choose.Â
Lens Materials
The lens material selection is one of the key factors in getting the best possible vision. There is a plethora of lens material types, and there is no ‘perfect’ material that suits everyone. A combination of prescription strength, frame design, lens coatings and lens treatments will influence your optician’s decision on what lens material is right for you. Some of the more common lens materials are listed below, in no particular order:
- Glass – Optically very clear, very scratch resistant, heavy, not compatible with many frames, tints, coatings, etc. Also very brittle. But can allow high prescription lenses to be made thinner than plastics.Â
- CR39 (Plastic) – Developed in the 1940s. Optically similar to glass, lightweight, compatible with nearly all frames, coatings, and tints. But it’s brittle, not good for rimless glasses, needs anti-scratch coatings. Most affordable option, but considered the “basic” option. 1.50 index.Â
- Polycarbonate – Suitable for almost any frame, including rimless. Ultra durable, good compatibility with modern coatings and treatments. Ultra lightweight. Poor optics with a low abbe value (30- lowest of any optical material). Only moderately thin, and easy to scratch. AVOID if you want the best vision possible. 1.59 index.Â
- Trivex – Invented in the 2000s. Great optical clarity, ultra durable, lighter than polycarbonate, moderately thin (~10% thicker than polycarbonate), decent compatibility with lens coatings and treatments. Up to 10x more impact resistant than a CR39 lens. A bit more expensive than Polycarbonate. Best choice for many people with low to moderate prescriptions. 1.53 index. Not always compatible with the widest range of lens coatings and treatments.
- High Index – Refers to the ability of the lens to refract (bend) light. Can come in 1.60, 1.67, 1.74 and other versions. Good choice for strong prescriptions to minimize lens thickness and weight. Can be more prone to reflections, so a premium anti-reflection coating is a must. Zeiss 1.60 index has an Abbe score of 42, nearly that of Trivex. 1.60 material can be a great alternative to Trivex and generally has a higher compatibility with photochromic lenses and other advanced lens options. High index lenses are good for prescriptions greater than +/- 1.50. Â
For a more detailed video on all the lens material types, check out Robert’s video below. He covers glass, CR39, polycarbonate, Trivex, and high index. He covers the pluses and minuses of each type, which should give you a good idea of what might be the best material for your needs.
If you have a high prescription, then you are probably conscious of how thick your lenses are. Check out the video below on tips and tricks on how opticians can make your high prescription lenses the thinnest possible.
Bottom Line: Depending on your prescription, lens coatings and treatments, there are a number of lens material options. Trivex is a great all-around performer but can’t be customized as much in terms of tints, photochromic options, and treatments. Rely on your highly skilled optician to explain the choices best for you. In my case, with a minimal corrective prescription and extensive use of tints, treatments and coatings, both of my recent optometrists recommended high-index 1.60 as the best choice.Â
Lens Design
The biggest misconception that average consumers have is that any lens made to the same prescription will give you the same vision. This is SO not the case! Lens design is the biggest contributor to the quality of your vision. Some lens designs will give you a better standard of vision than others. This can range from sharpness, peripheral vision, digital screens, night vision and driving lenses. In general, the more advanced lens design, the better your vision (and usually higher cost as well). It’s all about matching the right design with your needs. There are three major types of lens design:
- Single vision lenses – Most common type of lens design. Same prescription strength in all areas of the lens. If you are under 40 years old, this is probably your daily pair of glasses. They can also be more specialized like reading or computer glasses, for those over 40.Â
- Bi-focal or tri-focal – These have very obvious lines in the lens that delineates the different areas of the lens. Used for a general purpose pair of glasses that also have a “built in” magnifier lens for reading. Visually can be very jarring to look through because of “image jump”. They can also make you look older. This technology is very old and no longer popular due to the visual disruptions of the different powers.
- Progressive (Varifocal) – Commonly known as no line bifocals or trifocals. These lenses incorporate various regions in the lens for distance (top), intermediate (middle) and near vision (bottom) but have no lines. These built-in magnifiers are called “add”. Think of these as the Swiss army knife of lenses. Great for your daily pair of general purpose glasses. But they are probably not well suite for extended computer use, for example. But I’ll cover that later in this post.
Freeform lenses represent the pinnacle of advanced lens design technology available today. While freeform technology offers significant potential, it does not automatically ensure a high-quality lens. The effectiveness of these lenses largely depends on the sophisticated algorithms and precise measurements taken by your optometrist and optician. These measurements are crucial inputs into proprietary lens design algorithms, which tailor the lenses to meet individual visual needs and preferences.
Zeiss ClearView Lenses
Introduced in 2023, Zeiss ClearView lenses are the best budget stock lenses that single vision users can buy. Stock lenses are mass produced, and thus are more budget friendly than their premium SmartLife Individual lenses, which I will also cover.Â
Zeiss engineers the ClearView lenses with 700 points of clarity in each lens. Even though they are clear, they still have 100% UV protection up to 400 nm. These budget friendly lenses are just for single vision users, which means you are probably under 40 years old. Or, if you need a pair of glasses dedicated to just reading, these can work as well.Â
Check out Robert’s video below for the killer combination of Gast frames, ClearView lenses, and PhotoFusion X.Â
Zeiss SmartLife Lenses
Zeiss SmartLife lenses represent the pinnacle of their lens design, available in youth, single vision, and progressive versions. SmartLife lenses are bespoke lenses, customized for your eyes and even the frames you use. Depending on the tier of SmartLife you choose, the most advanced version (SmartLife Individual 3), can factor in variables such as your age, frame bow angle, the distance from your eye to the back the lens, and more.
In early 2023, Zeiss upgraded their SmartLife Individual 2 lenses to the new SmartLife Individual 3. You can read their full press release for more details. Zeiss SmartLife lenses are available in single vision, digital, and progressive (varifocal).Â
The SmartLife Individual 3 lenses incorporate advanced algorithms and integrate more data into the lens design process. For instance, Zeiss now considers the different centers of rotation (CoR) for both vertical and horizontal eye movements (about 2.8 mm apart), which they claim results in a wider field of clear vision. Previously, only an averaged CoR value was used. Horizontal CoR tends to have less variability than vertical CoR, due to eye anatomy and posture. Refer to the chart below for additional improvements made in the SmartLife Individual 3 lenses.
In the video below the official Zeiss channel features Robert and explains some of the enhancements in SmartLife Individual 3 lenses.Â
Zeiss DriveSafe Lenses
Driving a car, particularly at night, comes with its own unique challenges. To address nighttime glare caused by oncoming traffic, low light levels and dynamic vision, Zeiss developed the DriveSafe lenses and coating. They are offered in both single vision and progressive (varifocal) versions.
I personally haven’t used this lens type, so I can’t comment on how well they work. But if you want a super deep dive, check out ZEISS DriveSafe: Safety and comfort for challenging driving conditions. Robert also has a good video on the topic.
Progressive (Varifocal) Lenses
Progressive lenses are the state-of-the-art lenses. These are most commonly used for people over 40 where you need distance, intermediate, and near vision correction. I had LASIK quite a long time ago and only recently did I need any type of vision correction, due to presbyopia (natural aging of the eye where close up focusing becomes harder). My distance vision only has a tiny correction (-.25/-.50…thank you LASIK), whereas my “add” for reading is larger and has increased over the years.Â
Lens brand and type of progressive design can give you COMPLETELY different visual experience, for better or worse. A premium progressive lens from brand A might be awesome for your needs, but brand B might be terrible even though they are the same prescription strength. Or even within a brand, lens design A might be perfect for one use case (like driving), but very bad for using your computer. Selecting a highly skilled optician to help guide you through all the choices is key.
Progressive (varifocal) lenses have few downsides:
- Distortion: The amount of distortion greatly depends on your prescription strength and the lens design. You will need an adaptation period to adjust to using progressives and learn to move your eyes or head to use the proper lens area for the distance of what you are looking at.
- Customizable: This is a positive and a negative. Since there are so many lens designs, finding an optician that can understand your vision needs and translate that into the best lens design choice is VERY hard. Progressive lenses can be highly custom to your lifestyle, your prescription, and how you will use them (computer, driving, etc.).Â
- Cost: Premium custom progressive lenses with premium lens coatings can run USD $800+ for JUST the lenses, without insurance. Add Photofusion X for sunglasses, and you could be looking at USD $1000 or more for the lenses. Frame cost would be on top of the lens expense. Yes, getting the best possible vision in 2024 if you are 40+ years old IS expensive.Â
There are thousands of progressive lens designs available, each with its own strengths and weaknesses. Due to the inherent limitations of optics, no single lens can be considered “perfect.” Consequently, brands offer different progressive lens designs tailored to specific activities, such as driving, computer use, sports, or general daily use. Within these categories, opticians can further customize lenses to meet individual needs.
Finding a skilled optician who understands these options and can match you with the most suitable lenses is crucial. A knowledgeable professional can help you navigate the vast array of choices and ensure you receive the best possible visual experience.
Watch the video below for Robert’s take on the best and worst progressive (varifocal) lens manufacturers. He rates several brands from A to F, and yes, one brand did get an F rating.
Spoiler Alert: For most people seeking general-purpose progressive glasses, the Zeiss SmartLife Individual 3 line is considered top-of-the-line. Additionally, Zeiss Office lenses are highly recommended as dedicated lenses for all-day computer use. I personally use both types of Zeiss lenses, and they are nearly as perfect as the laws of physics allow. However, it is essential to consult a top-tier optometrist who is well-versed in the Zeiss product line to ensure you are paired with the ideal lenses for your needs.
After years of researching eyewear and trying different lens brands, I have found that Zeiss offers the best family of lenses for my eyes. In the USA, many optometry offices are aligned (or owned by) EssilorLuxottica, which often limits choices to Essilor lenses. However, some offices are more independent and tend to favor the Zeiss ecosystem.
Bottom Line:Â If you have tried progressive lenses in the past and were dissatisfied, it was likely due to a poor choice in lens design or an incorrect prescription. In Part 3, I will share tips for finding a top-tier eyewear professional to ensure the best possible results.
Reading vs. Computer Glasses
As individuals age, it is common to experience difficulty focusing on objects up close, a condition known as presbyopia. This typically begins in one’s 40s and often necessitates the use of corrective eyewear, such as reading glasses or computer glasses. Understanding the distinctions between these two types of glasses is essential for selecting the most appropriate solution for your visual needs.
Focal Points and Design Differences
The primary distinction between reading glasses and computer glasses lies in the focal point for which they are designed. Reading glasses are optimized for close-up tasks, such as reading a book or viewing a smartphone, which typically occur at a distance of 12 to 16 inches (30 – 40 cm). In contrast, computer glasses are tailored for intermediate distances, usually between 24 to 30 inches (60 – 76 cm), which is the typical range for viewing a computer monitor. For example, my monitors are at a distance of 28 inches (71 cm), and I provided this number to my optometrist during my visit. My optometrist also measured my reading distance, so I could get the best possible close up vision.Â
Lens Power and Prescription Variations
The lens power required for these different focal ranges varies. Reading glasses generally require a higher “add” power to accommodate the closer reading distance. Meanwhile, computer glasses are designed with a reduced add power, often about 60% of the reading prescription, to provide clarity at the intermediate distances typical of computer use.
For a more comprehensive understanding of these differences, consider watching the detailed comparison provided by Doctor Eye Health in the video below. This resource offers insights into selecting the right eyewear for your specific needs, ensuring optimal visual comfort and performance.
Even with the most advanced and costly progressive lenses, such as the Zeiss Smartlife Individual 3, you may find that specialized lenses are necessary for prolonged computer work. While these progressive lenses are excellent for everyday use, they may not provide optimal comfort or clarity for extended periods in front of large monitors.
Limitations of Progressive Lenses for Computer Work
The challenge arises from the limited intermediate viewing area within progressive lenses. My monitors are positioned at an intermediate distance of 26 inches (66 cm), which occupies only a small portion of the lens. This necessitates precise positioning of my head and eyes to achieve sharp text clarity, and even then, the clear area is quite narrow. Such constraints can lead to eye strain or neck discomfort over time.
As shown in the Zeiss graphic below, you can see the problems with trying to use traditional reading lenses or general-purpose progressive lenses with your computer. Neither provide a good solution.
Advantages of Computer Glasses
Computer glasses are specifically designed to offer a broader field of view at the typical working distance of computer monitors. There are two main types of dedicated computer lenses:
- Dedicated Single Vision Lenses: These have a focal point set at arm’s length.
- Office Progressive Lenses: These feature computer vision at the top and reading vision at the bottom.
Personally, I use the Zeiss Office “Book” progressive lens design. The “Book” version of the Zeiss Officelens allows me to view almost my entire 39-inch ultra-wide monitor or dual 27-inch monitors without having to move my head. The image remains virtually distortion-free, and the text is razor-sharp, providing a visual experience akin to having the eyes of a 20-year-old.
Customization and Cost Considerations
Zeiss offers three variations of Officelenses, each tailored to different primary focal distances (as illustrated in the graphic below). For large or dual monitors, the “Book” version suits my needs exceptionally well. Additionally, your optician can customize the focal distance to match your specific setup. I measured the exact distance to my monitors and shared this information with my optometrist to achieve the best results.
While fully customized office progressive lenses can be expensive, typically costing over USD $700 without insurance, they can include features such as 1.60 high index material, blue light blocking, and Duravision Platinum anti-reflective coating.
For further information, you can refer to the following resources: Zeiss Officelenses (1), Zeiss Officelenses (2), and the Zeiss Officelens PDF brochure.
Check out the video below which clearly explains the Zeiss Officelens portfolio.Â
In the next video Robert covers several aspects of getting the perfect pair of computer glasses, even if you don’t normally wear a prescription.
Lens Tints Galore
Lens tints offer a versatile way to personalize the appearance and functionality of your eyewear. Whether you are looking to enhance the style of your optical glasses with light cosmetic tints or seeking the practicality of tinted sunglasses, there are numerous options available. Some manufacturers, like Zeiss, provide an extensive range of lens tints and treatments to meet various needs and preferences.
Types of Lens Tints
- Fixed Tints: These range from subtle cosmetic tints to darker shades suitable for sunglasses. They provide a consistent level of tint regardless of lighting conditions.
- Photochromic Lenses: These lenses adjust their tint in response to UV light exposure. Zeiss offers several options:
- Zeiss PhotoFusion X: Transitions from clear to an 80% tint, providing versatility in changing light conditions.
- Zeiss AdaptiveSun: Available in 60% solid or 75%/25% gradient tints, with the ability to darken up to 97%.
Robert is a big fan of using tints to personalize your eyewear and match your lenses perfectly with your frames. He has produced informative videos showcasing a variety of lens tints, emphasizing how the choice of tint color can significantly impact visual comfort and style.
Considerations for Photoreactive Tints
It is important to note that photoreactive tints rely on UV light to change their level of darkness. Since car windows block a substantial amount of UV light, tints such as AdaptiveSun, PhotoFusion X, or other transition lenses may not darken as effectively inside a vehicle. However, certain tints, like PhotoFusion X extra grey, can still darken up to 50% inside a car, although they may retain a slight residual tint indoors.
When selecting a lens tint, consider your lifestyle and environmental factors. For instance, if you live in a sunny beach location, a different tint might be more suitable compared to someone residing in the UK, where sunlight is less intense.
For inspiration and a visual exploration of various lens tints, check out Robert’s video below, where he showcases a diverse array of customer glasses featuring a spectrum of tints. This resource can help guide your decision-making process when customizing your lenses.
For a really cool demo of several lens tints and how they affect your vision, check out the video below.
Sunglasses: PhotoFusion X vs. AdaptiveSun
Zeiss offers two advanced lines of photochromic lenses: PhotoFusion X and AdaptiveSun. Both are designed to provide dynamic tinting solutions that adjust to changing light conditions, enhancing visual comfort and protection. Below is a comparison of these two technologies, highlighting their features and differences.
| Feature | Zeiss AdaptiveSun | Zeiss PhotoFusion X |
|---|---|---|
| Base Tint | Solid tint: 60%; Gradient: 75% to 25% | Clear |
| Maximum Tint | Up to 97% | Up to 80% |
| UV Protection | 100% UV up to 400nm | 100% UV up to 400nm |
| Reaction Time | 18 - 35 Seconds | Up to 90 Seconds |
| Availability | Available in UK/EU, NOT in USA | USA + UK/EU + Other |
I chose to order two pairs of sunglasses through Robert because I wanted Zeiss AdaptiveSun lenses, which are not available in the USA. Robert, based in the UK, has access to the Zeiss lab in Germany where these lenses are produced. For my regular optical glasses, which I purchased from my local optometrist, I selected PhotoFusion X lenses. These lenses remain clear indoors and transition up to an 80% tint outdoors, offering versatile protection in varying light conditions.
One reason I made the extra effort to obtain AdaptiveSun lenses is that the gradient version is ideal for digital device users. Why? In light to moderate UV conditions, the bottom section of the lens remains lighter, allowing you to easily view your phone’s screen. However, in high UV environments, the entire lens can darken up to a solid 97% tint, providing maximum eye protection. This adaptability makes AdaptiveSun lenses highly functional for smartphone users in demanding lighting conditions.
In the Zeiss graphic below, you can explore the range of AdaptiveSun options, including polarized, solid tints, and gradient tints. I personally own two pairs of AdaptiveSun sunglasses: one with the grey gradient tint and the other with the Pioneer polarized tint.
I prefer the Pioneer polarized lenses for activities at the beach or on the water due to their enhanced glare reduction, while I use the grey gradient lenses for everyday wear. This combination allows me to enjoy optimal vision and protection in various environments.
If you’re interested in learning more about Zeiss AdaptiveSun tints, I recommend watching Robert’s video below. He thoroughly explores all the tint options and demonstrates them in action. Additionally, he discusses how different tints perform in various climates, which is quite insightful. For instance, the ideal lens tint for someone in Southern California (me) might differ from the preference of someone living in the UK.
If you want to watch Robert’s full review of AdaptiveSun glasses, check out the video below. He covers all the color options, what to use while driving, when to choose a mirror coating, and more. If you add a mirror coating that can help your eyes feel cooler in bright environments as it blocks some IR light.Â
Check out the video below for a full tour of the PhotoFusion X review, where Robert showcases various tints and what tint he recommends for various use cases.
If you still have questions whether photochromic lens are right for you, Robert has the perfect video. View it below.
If you are interested in photochromic glasses, you need to pair them with the right frames. Check out Robert’s video below to find out the tips and tricks to match a frame to photochromic lenses.
Lens Coatings
Today’s consumers have a variety of lens coatings to choose from, each offering distinct benefits. These modern coatings can enhance the functionality and durability of your lenses and include:
- Anti-reflective (AR): Reduces glare and reflections, improving vision clarity and the cosmetic appearance of glasses. AR coatings are commonly used in camera lenses, binoculars, and eyeglasses to minimize halos, starbursts, and glare from computer screens.
- Scratch Resistance: Protects lenses from everyday wear and tear, extending their lifespan.
- Oleophobic (Oil Resistance): Repels oils and smudges, making lenses easier to clean.
- Anti-static: Prevents dust and particles from sticking to the lenses.
- Hydrophobic (Water Resistance): Causes water to bead up and roll off the lenses, enhancing visibility in wet conditions.
- UV Protection: Shields eyes from harmful ultraviolet rays, reducing the risk of eye damage.
- Mirror: Adds a reflective coating to the lens surface, often used in sunglasses for aesthetic appeal and additional glare reduction.
- Flash Coating: Provides a subtle mirror effect, offering a stylish look while reducing glare.
Some of these coatings can be applied to both the front and back of the lens, depending on their intended use. For instance, anti-reflective coatings are typically applied on both sides to maximize their effectiveness. Premium coatings, like Zeiss DuraVision Platinum, are designed to be durable, less prone to crazing (foggy appearance), and resistant to chipping. They also simplify lens maintenance, making them easier to keep clean.
In the figure below, you can see how various lens coating layers are applied, illustrating the complexity and precision involved in creating high-performance lenses.
For sunglasses, Zeiss DuraVision Sun is applied to the back of the lens. For more details check out Zeiss DuraVision (Optical) and Zeiss DuraVision Sun.
Robert is an enthusiast of flash and mirror coatings for lenses. A flash coating is an additional layer applied to the front of the lens, imparting a subtle hint of color. This can be combined with a base tint to create a highly customized appearance. In contrast, mirror coatings are designed to reflect as much light as possible, giving the lenses a mirror-like finish. It’s possible to combine flash and mirror coatings for a truly unique look.
For instance, my green acetate Barton Perreira Domino sunglasses feature a solid Pioneer green polarized tint with a ruby flash coating. The ruby flash coating adds a hint of red when viewed from an angle, enhancing the premium and custom appearance of the sunglasses.
If you’re interested in learning more about lens coatings, Robert has an informative 11-minute video that delves into the details. Check it out below to explore the possibilities of customizing your eyewear.
Blue Light - To Block or Not to Block?
The research on whether blocking electronic blue light is beneficial is mixed. Blue light can be broken down into two categories:Â
- Blue-violet 380 nm to 450 nm – High energy violet light (HEV). Implicated in long term retina damage.
- Blue-turquois 450 nm to 500 nm – May reduce melatonin levels, thus impacting circadian rhythms (sleep/wake cycle). Â
Long term blue light exposure may cause oxidative stress damage, ocular surface inflammation, and cell apoptosis. However, the research is very mixed and somewhat controversial for both portions of the spectrum. For a more detailed discussion, check out the NIH paper: Blue Light Exposure: Ocular Hazards and Prevention—A Narrative Review
Currently, there is no evidence that LEDs in normal use at domestic intensity levels or in screen devices are retinotoxic to the human eye. However, the potential toxicity of long-term cumulative exposure and the dose-response effect are currently unknown.
For typical LED consumer devices, most of their blue light energy is around 450 to 470 nm. As discussed later in this section, most clear blue light lens treatments only block some of the high-energy blue light, not the blue-turquois light which may impact sleep. Special yellow or orange tinted lenses can block more of the sleep impacting blue light.
Eye Strain and Sleep Disruption: Some studies suggest that blue light from screens can contribute to digital eye strain and disrupt sleep patterns by affecting the production of melatonin, a hormone that regulates sleep. Blue light blocking glasses or screen filters may help reduce eye strain and improve sleep quality for some individuals.
Lack of Strong Evidence: Other research indicates that the impact of blue light from screens is minimal compared to other sources of blue light, such as natural sunlight. The American Academy of Ophthalmology (AAO) states that digital eye strain is more likely caused by how we use screens (e.g., prolonged focus without breaks) rather than blue light itself. They recommend taking regular breaks and maintaining proper screen distance instead of relying solely on blue light filters.
Potential Benefits: Some users report subjective improvements in comfort and sleep quality when using blue light blocking glasses, suggesting there might be individual variations in how people are affected by blue light exposure.
The scientific consensus is not definitive, and more research is needed to fully understand the effects of electronic blue light on eye health and sleep. Personally I’m a bit skeptical of blue light from digital devices disrupting my sleep patterns. I try and follow good screen habits, like the 20-20-20 rule (every 20 minutes, look at something 20 feet away for 20 seconds), to mitigate digital eye strain.
Zeiss provides different bluelight protection options. Their latest innovation (released in 2021) is Zeiss BlueGuard, which is “baked” into some of their lens materials. BlueGuard can block up to 40% of the potentially harmful blue light between 400 and 455 nm. 455 nm is the ISO defined upper limit of potential blue light phototoxicity. These lenses also provide 100% protection from UV up to 400nm. Note: Essilor (part of EssilorLuxxotica) offers “Blue UV Capture“, but only filters up to 20% (half that of Zeiss). The “healthy” blue light wavelengths (455 – 500 nm) are not affected by BlueGuard.Â
By baking the blue light blocking properties into the lens material (vs. a surface coating) Zeiss reduced reflections by up to 50%. This can make the eyewear more comfortable to wear. I requested the Zeiss BlueBlock material for my dedicated computer glasses. It was a small up charge, so even if the evidence of any negative effects is mixed, it was only USD $55 more. Â
Summary
In the second part of my “Geek Chic Eyewear” series, I focused on the importance of lens selection, beyond just choosing stylish frames. The post covered topics such as single vision and progressive lenses, lens tints, coatings, and computer glasses, providing a technical guide to help consumers make informed eyewear decisions. I also explained key lens properties like the Abbe value and refractive index, as they significantly impact visual clarity and comfort.
The article also discusses various lens materials, including glass, CR39, polycarbonate, Trivex, and high-index lenses, each with unique benefits and drawbacks. It emphasizes the importance of selecting a skilled optician to customize lenses for specific activities and lifestyles, ensuring optimal vision quality.
Additionally, the post highlights advancements in lens technology, such as Zeiss SmartLife and DriveSafe lenses, and discusses the benefits of specialized lenses for tasks like driving and computer use. The series aims to equip you with the knowledge to have an informed discussion with your optician regarding the best lenses for your glasses.
In Part 3 of this series I cover optometry equipment, eye health and eye insurance, and how to find the best Zeiss eye doctor.
