Checking Instagram in Bed Could Make You Temporarily Blind

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Photo: Adam Hester/Blend Images

Two women in the U.K. experienced transient vision problems that happened either at night or right when they woke up and their doctors figured out it was related to using their phones in the dark.

Doctors detail the cases in a new report in the New England Journal of Medicine. A 22-year-old woman had trouble seeing out of her right eye at night for several months. Her doctor did an eye exam, screened for heart problems, and ran a bunch of other tests, before determining she was otherwise healthy. A 40-year-old woman had difficulty seeing out of one eye for up to 15 minutes in the morning. Again, eye and heart exams were normal.

When the women went to an ophthalmic clinic, specialists took detailed histories and figured out that the women were using their phones in the dark before falling asleep and right after waking up, respectively. After asking them to record their symptoms for a few days, they said that the vision problems were always in the eye opposite of the side they were laying on.

The doctors suspected this was because if a person lays on, say, their left side, their left eye is partially blocked by the pillow and adapts to darkness, while the right eye adapts to the light and does most of the viewing. Which is fine until you look away from the phone and, with both eyes uncovered in the dark, the right, light-adapted eye is perceived to be blind until it readjusts to the darkness. They tested this theory on themselves and also had trouble seeing out of one eye for a few minutes.

They said that although people look at their phones with both eyes the majority of the time, we are increasingly attached to the damn things and their brightness is only increasing so they expect doctors will see more and more cases like this. They wrote this one up in an effort to save people time and money.

“Our cases show that detailed history taking and an understanding of retinal physiology can reassure both patient and doctor and can avoid unnecessary anxiety and costly investigations.”

Read: If this happens to you, maybe try turning down your brightness before you send doctors on a medical goose chase — or work on breaking the habit entirely. You might even sleep better.

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