By Mark Wright, OD, FCOVD,
and Carole Burns, OD, FCOVD
July 31, 2019
Most patients don’t know that there is harmful blue light emitted from the sun and electronic devices that could damage their eyes.
What is the key information patients need about harmful blue light?
There is an inverse relationship between the wavelength of light and the amount of energy contained in the wavelength – the shorter the wavelength, the greater the energy. Blue light has a shorter wavelength than red light, therefore, it contains more energy.
The wavelengths from blue to blue violet to UV keep getting shorter and, therefore, increase in energy. UV has so much energy that it can cause sunburn, cataracts, snow blindness, pinguecula and pterygium, and even trigger skin cancer. But not all is bad with UV light.
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UV light in moderation helps us create Vitamin D which the body needs. The sun is the largest contributor of UV. The eye does a great job of protecting the retina from UV, but does not do much about the UV that hits the skin and the front of the eye. This is why we prescribe sunglasses that blocks 100 percent of UV light.
Similarly, there is both good blue light and bad blue light.
Bad blue light can contribute to the following problems:
• Macular degeneration
• Eye strain including digital eye strain
• Too much blue light before bedtime can cause loss of sleep
Good blue light can contribute to:
• Regulating circadian rhythm which helps both alertness and the sleep cycle
• Helping memory
• Helping cognitive function
• Elevating mood and even treating seasonal affective disorder (SAD)
The sun is the largest source of blue light, but there are man-made sources of blue light such as indoor lighting, flat screen televisions, smartphones, tablets and computer screens. When it comes to blue light, most of it gets through the eye all the way to the retina.
It’s important to know that blue light damage to the eyes is cumulative. That means that the damage does not heal, it just gets worse with every exposure. This is why we prescribe indoor and outdoor glasses that let the good blue light through and block the bad blue light.
You can also get filters for your digital devices that reduce the transmission of blue light. Some of these filters also serve as screen-scratch protectors. “Examples of blue light filters for digital devices include: Eyesafe (Health-E), iLLumiShield, RetinaShield (Tech Armor), Retina Armor (Tektide), Frabicon and Cyxus.”i.
Patients come to us for more than just help to see clearer. They also come to us for help keeping their eyes functioning well and healthy. Addressing UV and blue light with our patients helps us achieve those goals.