New England Journal of Medicine
Alim-Marvasti et al. presented 2 cases of a puzzling phenomenon of recurrent transient, monocular visual impairment. Through careful history taking, they found that these cases were associated with cell phone use.
In the first case, a 22-year-old woman presented with a several-month history of recurrent impaired vision in her right eye at night. She had an extensive ophthalmic and systemic workup, and all findings were normal.
The second case involved a 40-year-old woman with a 6-month history of recurrent monocular visual impairment upon waking that lasted up to 15 minutes. Investigations for a vascular source were normal, and aspirin therapy was started.
The patients were seen in the neuro-ophthalmic clinic, where a detailed history revealed that symptoms arose only after several minutes of viewing a smartphone screen while lying in bed in the dark (before going to sleep in the first case, and after waking up in the second case). The physicians asked both patients to experiment and record their symptoms. When they did, the patients reported that their symptoms were always in the eye contralateral to the side on which they were lying in the bed.
The physicians hypothesized that the symptoms were due to differential bleaching of photopigment, with the viewing eye becoming light adapted, and the eye blocked by the pillow becoming dark adapted. As a result, with both eyes uncovered in the dark, the light-adapted eye was perceived to be “blind.”
In a study approved by a research ethics committee, 2 of the authors monocularly viewed a smartphone screen at arm’s length and quantified the duration of sensitivity recovery in the dark, both psychophysically and electrophysiologically. Visual sensitivity was appreciably reduced after smartphone viewing, and recovery took several minutes. The reduction in sensitivity was measurable at the level of the retina.
Although most screen viewing is performed binocularly, some individuals use smartphones while lying down, when one eye may be inadvertently covered. Now, as smartphones are being used almost around the clock, manufacturers are producing screens with increased brightness for easier reading in varying light conditions. Thus, the authors suggest that cases similar to those described here are likely to become more common. Detailed history-taking and an understanding of retinal physiology can reassure both patient and doctor, and reduce the number of costly investigations.
The original article can be found here.