How Much of Hazardous Blue Light is Transmitted By Spectacle Lenses?

The first region of the visible light spectrum is called blue light. Blue light is beneficial to humans in color vision, night vision, and circadian rhythms.[1, 2] However, this type of light raises concerns as it carries high energy and can cause ocular damages, such as photic retinopathy. In addition to the sun, there are several artificial sources of blue light emission, such as lightemitting diodes (LEDs), light bulbs, and fluorescent light tubes. With the increasing use of digital bluerich LED-backlight displays, such as in mobile devices and tablets, users’ eyes are more exposed to blue light.[2, 3] Blue light can also induce eyestrain, however, the blue light-blocking lenses may reduce eye fatigue. Currently, some lens manufactures claim that their products can alleviate eyestrain and ocular discomfort associated with the use of digital devices.[5] This raises important questions about the efficacy of blue light-control lenses. Therefore, eight blank-white spectacle lenses (four with and four without blue light-blocking property) were collected from different optical companies. A spectrophotometer (Cecil Instrument, UK) was used to measure the blue light transmission. Three ranges of blue light were evaluated: 400–450 nm, 455–500 nm, and 400–500 nm. For the statistical analysis, non-parametric Mann–Whitney test was employed. A P-value ≤ 0.05 was considered statistically significant.