Most of us are aware of the harmful effects of ultraviolet radiation on the human skin and eyes, but how many of us know that blue violet light, a small spectrum of the visible light spectrum, also poses health hazard to the eyes? ‘Blue light hazard’ is the new term researchers have coined to describe the danger this light spectrum presents to retinal cells.
Apart from the sun, blue violet light is also emitted by a number of modern artificial sources of light as well as digital devices that are widely used today. Computers, smartphones, LEDs and CFLs are all artificial sources of blue light that are ubiquitous today. With a much increased usage of these devices and light sources in our lives, our cumulative exposure to blue light has increased tremendously today.
Explaining blue light
The electromagnetic radiation consists of a wide range of wavelengths but the human eyes are capable of perceiving only a small band of this spectrum. We term this band ranging roughly from 390 to 700 nm (nano metre) as the ‘visible light’. If we divide this spectrum of light into further bands, we arrive at blue, green and red lights.
Blue light has a wavelength of between 380 nm and 500 nm, making it one of the shortest, highest-energy wavelengths. While this range of visible light spectrum plays a generally beneficial role on health, in particular by regulating the internal biological clock, a small but specific section of this band has been found to cause damage to retinal cells.
Because they have shorter wavelengths and higher frequency and higher energy, blue light waves create flickering and glaring effect on the eyes. This is perhaps why prolonged exposure to computers, television and smartphones causes strain to the eyes, headaches or fatigue. Researchers believe that prolonged exposure to blue light may cause retinal damage and contribute to age-related macular degeneration, which can further lead to loss of vision. In most cases, this photochemical damage accumulates over a lifetime.
And then there are digital screens everywhere. Computers, cell phones, flat-screen televisions and tabs are just among a few of the devices that emit blue light. With their wide-spread use, not only has our cumulative exposure to blue light increased, but the duration of exposure is also radically higher today as compared to say five years back.
Researchers come up with preventive mechanisms
Researchers at Essilor and the Paris Vision Institute have succeeded in identifying the very narrow band of blue light that is associated with photo toxic damage of the retinal cells. The culmination of this research has led to the development of lenses that has the ability to selectively filter the narrow but harmful wavelengths of blue light that are damaging to the eyes while allowing the healthy band of blue light to play its normal roles. The technology has been incorporated in the latest spectacle lenses manufactured by Essilor such as Crizal Prevencia and Eyezen.
Any preventive mechanism has to also include greater awareness and attempts to reduce exposure of harmful blue light.
Ways to protect your vision from increased exposure
Limiting the amount of screen time is very important for the generation that lives by digital devices. While one cannot do away with the requirements of work, we can certainly reduce the leisure time spent on digital devices. Reducing time spent on chatting and surfing the Internet can be helpful in reducing eye strain, headaches and digital mental fatigue.
Taking regular breaks from screen time also helps. Stand up from your desk every two hours and just walk around the workplace for five minutes. Blink more often.
Using screens and digital devices in a correct posture is also important. Make sure the screen causes minimal glare, reduce brightness and surrounding lights and make sure the screen is always right ahead of your face to ensure least strain on the eyes.
Wearing protective eye wears in front of digital screens has emerged as the most viable preventive option in the face of increasing prevalence and exposure to blue light radiation. Studies have also showed that wearing protective lenses with blue light filters helps reduce symptoms of eye strain and fatigue.
Dr Ira Chopra is a consultant eye surgeon at Paras Hospitals