CLINICAL

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Blue Light Basics

An overview of the dangers of this spectrum and how to protect your patients

KIRK SMICK, O.D., F.A.A.O., MARROW, GA.

Blue light plays a paradoxical role in health and vision, providing both beneficial and harmful effects. Research has shown that healthy blue light has positive effects on the body, such as helping with circadian rhythm and enhancing mood. (See “The Bright Side,” below.)

However, due to major leaps forward in technology, people are experiencing increased exposure to harmful blue light from LED computer, video game and smartphone screens. In addition, now that the U.S. and other parts of the world have initiated the phase out of incandescent light bulbs in favor of more energy-efficient luminescent sources (fluorescent bulbs, LEDs), we will experience even greater exposure to blue light. More over, lighting industry leaders say they believe that more than 90% of all light sources worldwide will be based on solid state lighting products and LEDs by 2020.

Given that research reveals blue light can be harmful for the eyes, it’s essential we understand its negative effects and how to safeguard our patients.

Here, I discuss these items.

Harmful effects of blue light

Blue light damage occurs when a photosensitizer absorbs photon energy of a specific wavelength (415nm to 455nm) setting in motion a series of intracellular chemical reactions. Rods, cones and retinal pigment epithelium (RPE) cells of the outer retina — the cells responsible for photon absorption and visual transduction — are rich in photopigments and, therefore, susceptible to photochemical damage.

During very prolonged or extreme blue light exposure, an accumulation of all-trans-retinal (ATR) can occur in the photoreceptor outer segments (POS). The ATR is photosensitive to light ranging from violet to blue, with an absorption profile decreasing from 400nm to 500nm.

When the antioxidant defenses begin to falter, as they do in advanced age, this ATR photoactivation can induce an oxidative stress in the POS. When the POS are oxidized, they cannot be correctly phagocytized by RPE cells. This incomplete intracellular digestion generates lipofuscin granules in the RPE. The end result is RPE degeneration and photoreceptor death. Several retinal pathologies can be linked to RPE and photoreceptor degeneration, including AMD, retinitis pigmentosa and Stargardt’s disease.

Through the last 20 years, many studies have linked the role of sunlight exposure to the prevalence of AMD. For example, the EUREYE study reveals significant associations between blue light exposure and neovascular AMD in individuals having the lowest antioxidant levels. Another study from Archives of Ophthalmology performed on 838 fishermen in the Chesapeake Bay area shows patients with advanced AMD were exposed to high levels of blue light through the preceding two decades.

Addressing it with patients

Blue light damage is a concern for all patients. Therefore, it is critical to take a proactive approach in order to help prevent or minimize damage caused by blue light. Practitioners need to begin counseling their patients on the potential hazards of blue light, particularly for children because of their longevity of life and their newfound interest in electronic devices — smartphones, tablets, computer screens, etc. — that emit blue light. These discussions need to happen in the examination room by the doctor.

For my patients who have already started exhibiting signs of AMD, I prescribe specialized blue light-filtering lenses. Specifically, a number of companies have developed lenses that have selective protection designed to simultaneously filter harmful blue light — blue-violet and UV light — while allowing beneficial blue light to pass through. (For a list of select lenses, see “Blue Light Lenses,” above).

Even those patients not yet exhibiting signs would benefit from the use of blue light-filtering lenses. As these specialized lenses become more cosmetically appealing to patients, they will be the new standard. Also, for all patients, wearing sunwear when outdoors is mandatory, particularly for children. In our office, we prescribe an E-SPF of 50 for young patients.

Act now

Harmful blue light can have devastating effects on vision. With the growing popularity of LED screens and lighting changes, it is imperative to take action to protect your patients’ eyes through proper prevention. OM

Dr. Smick is owner and chief of optometry services at Clayton Eye Center in Morrow, Ga., and currently serves as chairman of the continuing education committee for the AOA. Send comments to optometricmanagement@gmail.com.