Sponsored by IOT
By Tina Lahti, ABOC
In the last article, we covered lens materials and coating options, and their effect on lens optical performance. We briefly covered blue light attenuating lenses and coatings with a promise to share more in this June article. To that end, this article will cover the limits and benefits of the two types of blue light lenses in the market (indoor and outdoor). More and more consumers search blue light on the internet as they experience increased concern about the effects of digital screen time on eyes. They come to you for guidance and present you with the opportunity to help them understand the different types of blue attenuating lenses and coatings and their function.
As I stated in Part 25, there are a lot of lenses and coatings out there that make claims about protecting the eye from blue light or increasing wearer comfort in certain conditions, especially night driving or use of digital devices. If these products make wearers more comfortable, I am all for them. But I am always concerned when I hear and see product claims that are very different from what I know the product is doing. First, let’s talk about what blue light is. In the industry we’ve never really defined it. I’m going to define it today as light between 380 and 500 nanometers. I’ll further define a sub-category of high energy visible light, which is the light just above the UV spectrum that can be very penetrating, HEV light is 380 to 420 nanometers. If you’re going to recommend products that attenuate blue light, you need to make sure you know what these lenses do. Please keep this in mind. Blue light is visible. If you have a lens that is clear, it’s not “blocking” all blue light. Because to block is to stop it, not reduce it. The first type of blue light lens we’ll cover is used outdoors and is meant to protect the eyes from the blue wavelengths inherent in intense sunlight. Only a sunglass or fully activated photochromic lens can provide high level protection from solar blue light. Your customers generally lack awareness of the potentially harmful effects to their eyes and their child’s eyes from excess exposure to solar HEV blue light. This presents the optician with a huge opportunity to make the patient aware that sun damage from both UVR and HEV is very real, and protection should start with their children. Use their increased awareness of digital blue light to point out that the sun is magnitudes more intense and has the potential to harm the eye just as it harms the skin. According to animal studies, retinal cells (pigment epithelial and photoreceptor cells) absorb HEV light which can cause acute and chronic damage and lead to irreversible damage and cell death. But, and this is a big but, excess exposure happens from excess sunlight, not daily levels of screen exposure (laptop, PC, tablets or smartphones). Only a fully activated photochromic lens or level C sun lens provides a high level of protection from outdoor solar UVR and HEV blue light.
So, addressing the elephant in the room, patients deserve to know they need protection from HEV blue light outdoors in addition to 100 percent UVR. This is good for the patient and the practice since you will sell more photochromic and sun lenses, which is good for the patient and good for the practice. As I stated, clear or nearly clear blue filter lenses do not provide adequate protection from sun exposure, so what do they do? The second type of HEV blue light attenuating lens options are for indoor use to attenuate filter varying degrees of various wavelengths of HEV blue light from screens. These lenses are clear or nearly clear lenses that have the HEV blue wavelength filter as part of the lens monomer to absorb a percentage of selective HEV blue wavelengths, or the blue filter is a coating that reflects a percentage of certain HEV blue wavelengths. Each manufacturer can provide you with a transmission chart. Important note: these lenses claim to improve visual performance by absorbing some of the HEV blue light from screens improving contrast sensitivity and increasing comfort from symptoms related to extended time spent staring at screens and focusing at near, but they should never be presented as protection against solar HEV blue light. Review the manufacturer’s claims carefully to be certain that you are not misleading your customer.