There are quite a lot of technical terms to get your head around with glasses, but two of the most confusing are anti-reflective coatings and anti glare glasses. While using these terms interchangeably, it’s worth noting that there is a very slight difference between them.
Fortunately, unless you are a glasses manufacturer, you don’t need to worry about the fine difference between anti-reflective and anti glare too much as, by and large, glasses sold with either an anti-reflective or anti glare coat are likely to cover all the bases and work in very similar ways. Both solutions will improve and optimize visual clarity, ensuring that external light sources do not produce bright, distracting visual artefacts on your glasses.
That said, there is a notable difference between the two, even if the terms are often used interchangeably. As you’re clearly more engaged than the average consumer, let’s go into the details of what makes these two different types of lens coating different.
Why Do I Need an “Anti-Reflective” or “Anti Glare” Coating?
While regular lenses reflect around 8% of the light hitting the lens, high-index lenses can reflect up to a whopping 50%. These reflections result in eyestrain which can result in discomfort. In low light conditions, these reflections become more visible for users. This can make activities such as driving at night less than ideal.
Anti-reflective and anti glare coatings reduce the reflections which cause this eye strain greatly, allowing around 99.5% of light to pass through the lens, resulting in a much more comfortable experience.
Thus, these coatings can significantly improve the glasses-wearing experience—especially for those who require high-index lenses.
Anti-reflective vs Anti Glare
The key difference between anti-reflective coatings and anti glare pertains to the capacity at which they diffuse or eliminate anomalous light from different angles. In short: anti glare coatings will protect against external light sources entering the glasses, while anti-reflective coatings will protect against both internal and external light.
To get into the physics of it, anti glare solutions equip glasses with diffusive properties which diffuse light that would usually be reflected off of the surface of your lens. This means that instead of producing specular reflection, it creates a diffuse reflection. Instead of the light ray reflecting directly off the lens, it is broken up into many weaker rays, meaning the reflection is far weaker or, often, unnoticeable. This means that anti glare coatings significantly reduce the amount of light that is reflected off the surface of the lens.
On the other hand, anti-reflective lenses go a step further. These solutions use diffusive properties to diffuse both external and internal light. While “internal light” might sound strange, it refers to the small number of transitional light waves which are let loose as the light goes from one medium (in this case, air) into another (the lens). If unchecked, these small light rays can reflect within the lens itself, causing strange visual artefacts that lead to eye strain and discomfort. While these internal reflections may still be present in glasses with anti glare coatings, anti-reflective lenses go the extra mile to ensure the best user experience possible.
Can You Really Tell the Difference?
Whether you can tell the difference between the coatings will depend on your location and the lighting present. Most of the time, from a user’s perspective, the experience between these coatings will be largely similar—given the fact that the majority of visual artefacts come from external sources, not internal ones.
That said, anti glare coatings are typically visible to the human eye, while anti-reflective coatings are essentially invisible.
Because of this fact, most glasses manufacturers and opticians will opt for anti-reflective coatings, as they provide glasses wearers with the best all-around experience: improving visual clarity, reducing eye strain, and reducing haloing of light at night. It is also worth noting that anti-reflective coatings can be used on the vast majority of glasses lenses, reducing visual glare in regular spectacles, sunglasses, and more.
Overall, in the consumer sphere, the two terms are usually used interchangeably, which can result in a frustrating experience for those who understand the subtle difference between anti glare and anti-reflective coatings. However, given the superiority of anti-reflective coatings, you are likely to find them far more widely available for glasses than anti glare coatings. Now that you know the difference make sure you check with your optician to ensure you are getting the type of coating you want before purchase.