Tue, Oct 15, 2019 - Page 1 News List

Extended phone use in dark may lead
to color blindness

By Hung Chen-hung and Dennis Xie  /  Staff reporter, with staff writer

A 16-year-old girl, surnamed Liu, who had acquired “red-green color blindness,” on Sunday waits to cross a road in Kaohsiung.

Photo courtesy of Hung Chi-ting

An ophthalmologist warned people against using their smartphones in the dark for extended periods after a teen was diagnosed with acquired “red-green color blindness.”

Hung Chi-ting (洪啟庭), an ophthalmologist with Fooyin University Hospital in Pingtung County, on Sunday said that last month he treated a 16-year-old girl who came to him complaining about her inability to distinguish the colors of traffic light.

Hung quoted the girl, surnamed Liu (劉), as saying that after summer vacation, she had had several risky encounters when crossing the street.

It was only when she was out walking with her family that they noticed that she mistook the red light for green, Liu said.

She also experienced a deterioration in her ability to see in the dark, Hung said.

Whereas it used to take her about 25 minutes for her eyes to adapt and be able to distinguish things in a dark room, now it takes her about an hour, he quoted Liu as saying.

After checking her vision, Hung said that there were no signs that Liu’s nearsightedness had worsened, as it remained at 4 diopters.

Neither did she have glaucoma, cataracts, retinal detachment, hypertension, nor a family history of other rare diseases, he added.

Liu said that since the beginning of summer vacation, she had not spent a minute away from her smartphone, adding that she would turn off lights in her room and use her phone in bed, averaging about 10 hours of screen time each day.

Hung said that if rod cells (responsible for vision in low-light conditions) and cone cells (responsible for vision in bright light and color sensing) are under oxidative stress caused by long-term exposure to blue light, free radicals and reactive oxygen species — both of which attack and damage cells — would appear around the multilayer cells of the retina.

That is what causes acquired color blindness and impaired dark adaptation, Hung added.

Fortunately, Liu’s condition was in the early stage and she has stopped using her smartphone, Hung said, adding that her vision has recovered.

Congenital color blindness is untreatable, and the red-green color blindness would have deteriorated and became complete color blindness had the girl not been treated early, Hung added.

People should not use their smartphones for more than five hours a day and take 10-minute breaks every 30 minutes, he said.

Gazing at distant objects can soothe eye strain, while staring at the phone with the lights off is not recommended, as blue light damages eye cells even more in the dark, he added.

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