For two women in the United Kingdom, mysterious vision problems that happened only at night or early in the morning turned out to have a rather innocuous cause: looking at a smartphone in the dark.

　　英国的两位女士只在夜晚或者是早上出现了神秘的视力问题，结果是由一个相当无伤大雅的原因引起的——那就是在黑暗中看手机。

　　In the first case, a 22-year-old woman told her eye doctor that she had trouble seeing out of her right eye at night while she was in bed. These episodes happened multiple times a week for a year. Each time, she said she could only see the outlines of objects with her right eye, although her vision was fine in her left eye, and in both eyes the following day.

　　在第一个案例中，一位22岁的女士告诉她的眼科医生说，她的右眼在每晚躺在床上的时候看不清。这些现象在一年之中每周要发生很多次。每次她都说，她的右眼只能看出事物的轮廓，尽管她的左眼视力很好，第二天两只眼睛的视力就全部恢复了。

　　In the second case, a 40-year-old woman told doctors that she couldn't see out of one eye when she woke up in the early morning, before sunrise. This vision problem lasted about 15 minutes, and happened on and off for six months, the report said.

　　报道称，另一个案例中，一位40岁的女士告诉医生说，她在早上起床后日落之前，其中一只眼睛看不见。这种视力问题持续15分钟，半年之中会断断续续发生。

　　In both cases, doctors later discovered that these vision problems happened only after the women had viewed their smartphone for several minutes, while lying on their side in bed.

　　在以上的两个案例中，医生后来发现这些视力问题都是因这两位女士躺在床上持续几分钟看手机之后发生的。

　　The doctors hypothesized that these problems happened because the patients, without realizing it, were looking at their phone with just one eye, with the other eye blocked by a pillow when they were lying down. In this situation, one eye (blocked by the pillow) becomes adapted to the dark, while the other eye (looking at the smartphone) is adapted to the light, the doctors said. When the smartphone is turned off, the light-adapted eye is perceived to be "blind," until it also adjusts to the dark, the doctors said.

　　医生假设表示：这些问题的发生是因为病人在毫无意识的情况下使用一只眼睛看手机，而另外一只眼睛在躺着的时候被枕头所遮挡。在这种情况下，那只被枕头遮挡的眼睛已经习惯了黑暗的环境，而另外一只看手机的眼睛却习惯了光亮，医生说。当手机关机后，那只适应光亮的眼睛就被认为是“盲的”，直到它也习惯了黑暗。

　　The doctors also tried their own experiment, looking at their smartphones with one eye in the dark, and found that their vision was considerably reduced in one eye, and took several minutes to recover.

　　医生自己也做了尝试，在黑暗中用一只眼睛看手机，结果发现这只眼睛的视力大大降低，而且需要几分钟的时间来恢复。

（编辑：何莹莹）