April 4 2016, 11.30 PM IST || Pocket News Alert
Dr. Ira Chopra, Consultant Eye Surgeon, Paras Hospitals writes on how our eyes face a rising health threat with an inevitable switch to modern lighting techniques and increased usage of digital devices
The effects of harmful Ultra Violet Radiation on the health of skin and eyes have been well documented and much talked about in recent years. However, researchers today have identified that ultra violet light is not the only harmful component of light when it comes to visual health. The Blue Violet spectrum of visible light is another component that has the potential to cause damage to retinal cells of the eyes. In fact, researchers have coined a new term to describe the danger this light spectrum presents to critical structures within the eye. They call it “blue light hazard”.
Interestingly, blue violet light (wavelengths between 380 and 500 nm) is not just emitted by the sun but also by artificial sources of light such as LEDs, CFLs, and digital devices such as computers and smartphones. Given the increased usage of new age lighting devices and an increasingly ubiquitous existence of smartphones and computers, what we are witnessing today is a much higher exposure to blue violet light than say five years back.
This development has prompted a new wave of research and studies in the field of ophthalmology as well as ophthalmologic optics. But before moving on to that let’s understand with greater precision the effects of blue violet light on the structures within the eyes.
What is Blue Light?
The small spectrum of the electromagnetic radiation which our human eyes are capable of perceiving is termed ‘visible light’. A human eye typically responds to wavelengths between 390 to 700 nm (nano metre). This entire visible spectrum can further be divided into different bands which includes 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.
Where is Blue Light?
Well, it is everywhere! While sun is the main source of blue light emission, it is certainly not the only source. Today, we are literally surrounded by sources of blue light and therefore continuously exposed to it.
While solar radiation is considered to have 25% to 30% blue light, the modern, energy efficient light sources such as CFLs and LEDs emit significantly higher amount of harmful blue light (roughly 26% of the light from CFLs is blue while an estimated 35% of light emitted by LEDs lies in the blue portion). On the contrary, the conventional, incandescent lamps which were widely used till a few years back, were noticed to emit very little blue light.
Besides, our eyes hardly stops working in front of digital screens today. The digital screen technology has evolved radically over the years, and many of today's electronic devices use LED back-light technology. Computers, cell phones, flat-screen televisions and tabs are just among a few of the devices that use this technology. 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.
What are the Solutions & Preventive Mechanisms?
The natural filters of the human eye do not provide sufficient protection against blue light. Therefore, any preventive mechanism has to start with greater awareness and attempts to reduce exposure of harmful blue light. Researchers have also been off late working on mechanisms to help selectively filter the harmful wavelengths of blue light while transmitting the beneficial ones.
In this context, 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.
Protecting Your Vision
- 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.
- 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.
- Take regular breaks from screen time. Stand up from your desk every two hours and just walk around the workplace for five minutes. Blink more often.
- 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.
