When you were growing up, chances are high that your parent or guardian told you that if you sit too close to the TV your eyes would turn square.
Thankfully that never came true for anyone, but the older generation's concern about screens wasn't completely unfounded.
One woman has realised what can happen when you use your phone too much at night.
The unnamed patient from Shenzhen, a major port city in China's southern Guangdong Province, took herself to hospital after being unable to see using her left eye.
Doctors assessed the woman and discovered her mobile phone use at night had resulted in burst blood vessels.
Doctor Qiu Wangjian, from the Songgang People's Hospital said: "The patient stayed up all night playing on her mobile phone. The following morning, as soon as she woke up, she picked up her phone and started using it again.
"About five minutes later, the patient discovered that she was unable to see out her left eye. She couldn't see anything.
"Images taken of her eye showed large patches of blood on her retina, blocking her vision.
"We diagnosed her with valsalva retinopathy."
Now, you're probably freaking out about the health of your eyes and are committing to never using your phone at night with high brightness. But rest assured, the female patient eventually regained sight in her left eye.
Doctors said the superficial retinal vessels burst because of 'physical exertion'. In order to fix the condition, physicians user a laser to drill a small hole in her retina to allow the blood to flow from the burst vessels.
That's a pretty frightening mental image.
Doctor Qiu added: "It was important that we treated her quickly in order for her not to suffer any long-term effects."
The patient is now recovering from the procedure.
But don't think this is an isolated incident that couldn't possibly happen to you.
A woman in Taiwan had hundreds of holes burned into her eyes because she used her phone at the highest brightness at night.
Chen's eyes are incredibly messed up after using her phone constantly over the course of two years on full brightness.
They first became bloodshot and then started to hurt and that's when the 25-year-old sought medical treatment.
Her doctor said that she had been exposing herself to more than 600 lumens (which is a level of brightness) every day for two years when the recommended daily level is roughly 300.
According to the Mirror, exposing your eyes to just two hours of anything brighter than 600 lumens is like putting your eyes in a microwave.
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