Executive Summary
High-frequency rays such as blue and ultraviolet lights can damage our retina, leading to permanent loss of eyesight.
We encounter Ultraviolet rays only in the sunlight outdoors. So, wearing sunglasses is important, especially when in open spaces or on a beach.
Blue rays are there in the sunlight, outdoor lights at night, LED lamps, and modern-day TV, computer, and mobile screens. 25 min of continuous exposure to blue rays is enough to cause some permanent damage to your retina.
Eat foods or supplements high in nutrients called lutein and zeaxanthin. The article below explains what foods contain them in how much quantity.
Blue rays are a modern threat to our eyes. Over the years, it can accelerate eye damage and even lead to permanent loss of eyesight. How does that threat arise? And, what can you do to protect your eyes?
Science knows that the ultraviolet rays in the sunlight can cause cataracts and retinal damage. This can lead to age-related macular degeneration (ARMD).
Light rays
Any type of light has rays of various frequencies. We know that a prism, or a rainbow, separates these rays and we see a spectrum of all the rays in that light.
Some rays are not sensed by the eyes as colours. For example, infrared and ultraviolet rays are not seen as a colour by our eyes. However, they can cause similar damage to the eyes as visible rays.
Some light sources will have a lesser number of frequencies in them. This does not have anything to do with the intensity of light; we are just referring to the frequencies of light. The phrase used for that is the frequency spectrum.
The sunlight spectrum has a large number of frequencies. On the other hand, some lasers have rays of very few frequencies. Thus, their frequency spectrums are ‘narrow’ bands. In other words, a prism can hardly separate the rays of laser light.
To know which lights can harm the eyes, we need to know which frequencies of rays can cause more damage to the eyes.
Damage from light rays
As an engineering principle, when a ray of light hits a material that is not transparent, it will dissipate or release its energy inside the material. That will be the end of that ray.
However, for that, the ray will penetrate inside the material for a short distance, which you cannot see with your eyes easily. The penetration of the ray usually depends on its wavelength. The longer the wavelength, the deeper the penetration.
Another scientific fact is that a ray of higher frequency will have a shorter wavelength, and vice versa.
As a result, a ray of light will penetrate deeper inside a material if it has a lower frequency. It will release or dissipate its entire energy over a longer distance (penetration distance).
Turn the argument around, and you will realise that the higher the ray frequency, the shorter will be its penetration distance. So it will release all its energy over a shorter distance. This will dump a much higher energy density in that smaller length of penetration.
Thus, the higher the frequency, the more potential the damage that the rays can cause. Blue-coloured rays have the highest frequency, among the rays of the sunlight that we see. 25% of the sunlight is made of blue rays.
Ultraviolet rays have an even higher frequency. While our eyes cannot see them, they are also present in the sunlight. About five per cent of solar energy is in ultraviolet rays.
Thus, blue and ultraviolet rays in the sunlight can damage our eyes. So we are advised to wear sunglasses, when out in the sun.
Indoor lights
However, sunlight is mainly out in the open. Once you are indoors, the sunlight threat recedes.
The ultraviolet rays are usually not present in artificial lights, which we have indoors, and outdoors in the night. So even the threat from ultraviolet rays falls off once we get off the sunlight.
However, modern life ensures that the blue rays are still there indoors and in the outdoor lighting at night. Blue light is also present in the light that comes off computer monitors and mobile phones. Nearly 35% of this light is blue. The new LED lighting has even more, 50%, as blue light.
In other words, blue rays are hitting your eyes for nearly 16 hours a day. And, they can cause serious damage to the eyesight.
Two minutes of near-ultraviolet-ray or 25 minutes of blue-ray exposure is sufficient to cause some irreversible damage to the eye’s photoreceptors. Read: High energy visible light.
How to protect your eyes
One simple protection is reducing your screen time. Avoid, whenever possible, your exposure to blue rays, such as those from the TV, computer, and mobile phone screens. Read on this website: Eye strain and working–from–home.
Natural protection against blue light is a layer of pigmented (coloured) cells in the retina called Macular Pigment Epithelium. These cells are rich in anti-oxidants, Lutein and Zeaxanthin, obtained from food.
Lutein and Zeaxanthin absorb the blue light and prevent it from penetrating the retina further, hitting and damaging the delicate cells called cones and rods, which give us vision.
The longer the exposure to blue light, the more damage to cones and rods. Once these cells die, they don’t regenerate and the eyesight is lost permanently.
Sources of lutein and zeaxanthin
Lutein and zeaxanthin are available in egg yolks and green leafy vegetables such as spinach.
One study found improved night vision and visual acuity (reading smaller alphabets) in people with early signs of ARMD, after a year of taking dietary zeaxanthin.
The minimum requirement of lutein and zeaxanthin is not known. But studies that showed benefits have used 8 to 10 mg a day. You can get that from half a cup of cooked spinach, 2 cups of cooked green peas or 4 cups of cooked broccoli. Read: Lutein.
When the high-energy blue light hits oxygen-rich blood in the retina, it triggers inflammatory signals. Omega-3 fish oil is found to help reduce the resultant damage. Read on this website, a comprehensive article about Omega–3 fatty acids and fish oils.
Read: Protect eyes from computer blue light.
While blue rays can damage our eyesight, artificial lights, as a whole, can cause severe damage to the body. They can lead to disruption of circadian rhythm, which can lead to cancer, diabetes, obesity, heart disease, and depression. Read on this website: The dark side of bright lights.
Actionable tips
- Reduce the time you spend looking at a TV, a computer screen, or a mobile phone.
Reduce the screen time for everything, except my articles. 🙂 - Use sunglasses, when you are outdoors in the sun.
Use good quality sunglasses, which can filter out strong UV rays. - Eat foods that protect your eyes from blue ray damage.
Increase intake of egg yolks and green leafy vegetables. - Take lutein, zeaxanthin, and omega-3 oil supplements.
Eye damage is irreversible and permanent. Act before it sets in. - Be more and more careful as you age.
Follow steps 1 to 4 more rigorously as you age.
First Published on: 3rd March 2017
Image credit: Image by Freepik
Last Updated on: 1st July 2023