Two individual cases of women reporting temporary right-eye blindness have come to the attention of a team of London-based researchers from City University, King's College, the National Hospital for Neurology and Neurosurgery and Moorfields Eye Hospital. In both cases, the women experienced this problem repeatedly over the course of several months, and always while using their smartphones in the dark.
The condition these women have experienced is medically referred to as "transient monocular visual loss," and the research team believes it may be happening to more people that just these two. Their study, which has been published in The New England Journal of Medicine, focused on the similarities of the two cases. Both women were laying on their left side, using their phones in their dominant right hand, in the dark just before bed, and experienced temporary blindness in their right eye, the longest instance lasting approximately 15 minutes.
Further more, both were using just their right eye to view the screen and adjust to the change in brightness, while their left eye was covered, either by a blanket or pillow. Once they were finished with their phones, they were then unable to adjust to the darkness in their right eyes, and had to rely on their left eye for vision, which has not been exposed to the light of the screen. Curiously, the issue seemed to resolve after doctors suggested using both eyes, rather than just one.
While it would be easy to assume that the drastic shift in light levels would cause temporary blindness in both eyes, the opposite seems to be true in this matter. In fact, to further fortify their study, the research team subjected a group of participants to the exact same conditions that the two women experienced, and were able to recreate the issue, as well as the solution.
According to an excerpt from the study, "People frequently use smartphones while lying down, when one eye can be inadvertently covered. Smartphones are now used nearly around the clock, and manufacturers are producing screens with increased brightness. Hence, presentations such as we describe are likely to become more frequent. 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."