Focus on Fundamentals
When blue light is discussed, it is important to break it down into two separate categories: natural blue light emitted from the sun and artificial blue light from human-made sources, including digital devices and LED lights. The benefits and risks of overexposure or unprotected exposure to natural blue light are backed by substantiated and long-proven research. The sun plays a crucial role in regulating the body’s circadian rhythm, mood, and alertness. Excessive exposure to sunlight, especially without eye protection, can lead to conditions like photokeratitis and macular degeneration and can contribute to the speed at which cataracts develop.
The research regarding the effects of artificial light on the eyes is still inconclusive, as are the medical benefits regarding blue light protection in spectacle lenses and contact lenses. Whether there is a long-term benefit to wearing lenses that have a blue-light-blocking property to them is still only a hypothesis yet to be proved or rebutted. Our focus as eyecare professionals should be to stay informed, understand the different manners in which blue light filters can be added to sunwear and indoor eyewear, and balance patients’ concerns from an educational and research-based perspective.
Different Applications for Protection
Various options are available to incorporate blue-light-filtering properties into spectacle lenses; some are focused on filtering natural blue light, while others are specifically designed to focus on artificial blue light. Each offers different aesthetics and levels of blue light filtration. Below, we explore different ways lenses can provide blue light protection, from specialized coatings to innovative materials and adaptive technologies.
Lens Materials
Blue light filters, embedded into the lens material, are an aesthetically pleasing and virtually invisible way to have blue light protection without compromise or considerable cost.
Products such as Shamir Blue Zero filter blue-violet light emitted mainly by the sun, through a unique polymer lens material formula. Essilor BlueUV Filter System reduces exposure from sun and screens, with selective absorption of UV and blue-violet light and specific color absorbers inside the lens material. Zeiss BlueGuard incorporates blue light blocking properties in the chemical makeup of the lens material. These lenses provide up to three times (to a maximum of 40%) more filtering of blue-violet light than a regular lens while maintaining high lens clarity. Blue light is filtered up to 20% to 50%, depending on brand and blue light spectrum range in nanometers.
Colored or Tinted Lenses
Lenses that are tinted or colored (through polarization) are designed to block blue light. This is achieved to different levels by using specific colors that absorb or filter out blue wavelengths. The effectiveness of how much blue light is filtered out depends on the color and the material of the lens.
→ Amber or yellow lenses are highly effective at blocking blue light because they filter out a significant portion of the blue light spectrum, which ranges from about 380 nm to 500 nm. Amber or yellow lenses work by absorbing blue light, thus preventing it from passing through the lens and reaching the eyes. These lens colors are commonly found in glasses designed for computer use and are recommended by some optometrists to help improve contrast in low-light conditions, such as for night driving.
Amber lenses filter 50% to 70% of blue light and yellow lenses filter 40% to 60%.*
→ Orange or red lenses also effectively block blue light. These tints can filter out almost all blue light on the spectrum, making them even more effective than amber or yellow lenses. However, the depth and tone of orange or red can distort color perception more significantly, especially in indoor settings, which can be a hindrance for tasks that require accurate color perception.
Orange lenses filter 80% to 98% of blue light and red lenses filter 90% to 100%.*
→ Brown or copper lenses are popular for sunglasses as they provide a balance between blocking blue light and maintaining color accuracy. These tints and tones filter out some blue light while also enhancing contrast and depth perception. They are ideal for driving and outdoor activities to reduce glare and improve visual clarity, while keeping colors vivid and sharp.
Brown lenses filter 50% to 70% of blue light and copper lenses filter 60% to 90%.*
*Tint saturation and tone of color will affect the level of blue light filtration and estimates are based on a light spectrum range of 400 nm to 500 nm.
Photochromic Lenses
Color-changing, light-adaptive lenses offer a sliding scale of blue light protection, depending on the level of activation. The darker the lenses, the more light across various wavelengths, including blue light, is absorbed. Photochromic lenses such as Transitions, Zeiss PhotoFusion, Hoya Sensity, and others reduce the amount of blue light reaching the eyes in an activated level, providing protection similar to that of sunglasses.
Blue light is filtered up to 45% indoors and 90% outdoors, and varies based on brand and blue light spectrum range in nanometers.
Coatings
Blue light coatings have experienced a downturn in popularity due to their strong visual characteristics. The coatings work by reflecting blue-violet light, which can cause them to be visually apparent from an outsider’s viewpoint, with a strong purple or blue color that reflects off the lens surface. Most blue light coatings are targeted toward the blue-violet spectrum of 400 nm to 455 nm and combined with a UV coating. The coatings are typically recommended and targeted towards indoor use for computers and digital devices.
Blue light is filtered up to 35% and varies depending on brand and blue light spectrum range in nanometers.
