Glasses that filter out blue light can help prevent eye damage

Wearing lenses that block blue light doesn't noticeably impair sleep or vision.

Blue light causes more damage to the eyes than other wavelengths. While sunglasses can protect us from direct sunlight, which is the primary source of blue light, they’re generally not worn inside. This leaves people exposed to blue light from florescent lights and LED-backlit screens on computers and smartphones. Lenses specially designed to filter blue light in these environments can fill that gap. But blue light also serves vital functions, leading researchers to wonder whether reducing exposure to it all the time might also impact vision and sleep quality. Tsz-Wing “Jeffery” Leung and his colleagues put that to the test, asking computer users to wear commercially available blue-light-filtering glasses for a month. The glasses did reduce exposure to blue light, and most people using them noticed no changes to their vision and sleep. We asked Leung to tell us more.

ResearchGate: How is blue light harmful?

Tsz-Wing Leung: Light is a form of electromagnetic radiation that carries energy. The shorter the wavelength, the greater the energy. Because blue light has the shortest wavelength in the spectrum of visible light, it carries the highest amount of energy in the spectrum. Evidence suggests that blue light triggers more damages to the retina than other wavelengths. Of most concern is the potential link between blue light exposure and the development of age-related macular degeneration, which is the third leading cause of blindness worldwide. Excessive blue-light exposure has long been proposed as one of the causal factors of this eye disease.

RG: And what helpful functions does blue light serve?

Leung: Blue light plays essential roles for normal sensory and physiological functions, including color vision, night vision, and the body’s internal clock. The S-cone and rod photoreceptor cells of the retina reach their peak sensitivity under blue and blue-green environments. These two photoreceptor cells help our eyes to discriminate blue and see in dark environments. Blue light also helps our brain to stay awake in the daytime by inhibiting melatonin secretion.

RG: How do lenses designed to reduce exposure to blue light work?

Leung: There are two ways to reduce blue light through ophthalmic lenses. The first is by tinting the lenses with colors that absorb the blue light, usually brown or yellow. The second is by applying a surface coating on the lenses that reflects the short-wavelength radiations.

RG: What effects of wearing blue light filtering lenses did you test in your clinical trial?

Leung: In our recently published paper, we recruited young (18-30 years) and middle-aged computer users (40–55 years), and tested their ability to discriminate color and contrast through the blue-light filtering lenses. Questionnaires were also administered to access their sleep quality, night vision and other subjective performance when wearing the blue-light filtering lenses.

RG: What were the results?

Leung: We found that wearing the blue light filtering lenses did not significantly affect the tested visual perception and sleep quality of the wearers. However, young adults tended to be less satisfied with the tinted lenses because of the lens appearance and subjective feeling of color vision changes.

RG: Do you recommend that people wear lenses that filter blue light?

Leung: Because the blue-light filtering lenses tested in our study did not have adverse effect on visual performance and sleep quality, they could serve as a supplementary option for blue-light protection. Nevertheless, these lenses should not replace sunglasses to protect against sunlight, which is the major source of blue light.

Featured image courtesy of Scott Van Daalen.