Tue, Nov 14, 2017 - Page 4 News List

Yellow lenses best for reading: students

IDEAL:A study found that yellow-tinted lenses filter harmful blue light rays while preserving natural light, whereas dark-tinted lenses filter all natural light

By Hung Mei-hsiu and Sherry Hsiao  /  Staff reporter, with staff writer

Shu Guang Girls’ Senior High School students demonstrate filtering out blue light with a yellow lens on Tuesday last week at their school in Hsinchu.

Photo: Hung Mei-hsiu, Taipei Times

Eyeglasses with yellow or orange-tinted lenses provide the best light filtering while reading, according to research by a group of students from the Shu Guang Girls’ Senior High School in Hsinchu.

The students are to present their findings at Optics & Photonics Taiwan, the International Conference (OPTIC 2017) hosted by National Sun Yat-sen University in Kaohsiung from Dec. 7 to 9.

The students collaborated with a research team led by National Tsing Hua University department of materials science and engineering professor Jou Jwo-huei (周卓煇) — which specializes in organic light-emitting diodes (OLED) — to investigate whether dark sunglasses really protect wearers’ eyes.

“In the summer after their first year in high school, students discovered that under strong sunlight, many people choose to wear sunglasses to protect their eyes. However, can sunglasses really protect the eyes?” Shu Guang Girls’ Senior High School principal Yao Li-ying (姚麗英) said.

“The students formulated a research question and topic, and sought out Jou’s team, which is engaged in a long-term study on the effects of light rays and lighting on the functioning of the human retina,” Yao said. “Together, they wrote three research articles, and were invited to deliver their results at the OPTIC 2017.”

The students’ research focused on the effects of eyeglass lens color on the retina.

The students said that using a spectroscope, they analyzed light rays and found that yellow lenses are not only the most effective at filtering harmful blue light — five times more so than black or gray lenses — but also preserved the natural light source.

While dark lenses are capable of filtering out blue light, they also filter out natural sources of light, the students found.

The students said that yellow lenses cause the least damage to the retina and are suitable for use while reading.

Dark lenses are not appropriate for reading, they said.

The results upend assumptions that wearing dark sunglasses is always good, the students said.

They said that receiving the recognition of a national-level research conference was a huge encouragement for them.

“[My] research team has been studying OLEDs for a long time. Many studies show that the level of damage caused by blue light on the human retina is very high. Its influences on melatonin are also numerous. Long-term exposure to blue light at night has effects on both the female breast and the male prostate gland,” Jou said.

“The government should bolster its monitoring of blue light. Parents should not let their children be exposed to environments with harmful blue light — for example, using a smartphone for long periods of time or at night — and minimize its effects on the human body,” he added.

Light can cause considerable damage to the eyes, National Taiwan University Hospital department of ophthalmology attending physician Yeh Po-ting (葉伯廷) said.

He said a young female patient had shone her smartphone’s flashlight on the orbit of her eye for less than five minutes after an eyelash fell into her eye.

However, a fixed dark shadow afterwards appeared in her field of vision and her measurement of visual acuity dropped to 0.3, he said.

The patient recovered after six months of treatment, Yeh said.

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