To present the case of a patient admitted to the Vascular Neurology service with transient binocular vision loss most likely caused by smartphone use during the night. 

CASE REPORT:  A 68 year old woman with hyperlipidemia, hypertension and previous right medullary infarct secondary to vertebral artery atherosclerosis was referred from her optometrist’s office with several episodes of binocular vision loss over the previous weeks.  Whenever she got up to use the restroom at night, she consistently lost vision in both eyes for several minutes, after which her vision spontaneously normalized.  She denied any associated symptoms such as headache, nausea, weakness, or imbalance.  Ophthalmological evaluation including visual acuity, visual fields and fundoscopy was normal.  Neurological examination revealed residual findings from her previous stroke including a mild right Horner’s syndrome, right vocal cord paralysis and temperature loss in left hemibody.  MRI brain showed chronic microvascular disease and an old infarct in the right medulla. Upon further history taking, it was elucidated that the patient often read in bed on her smartphone for prolonged period of time, and that events occurred exclusively after smartphone use.  We checked the phone which, unbeknownst to her, was set at maximal brightness.  She was discharged home without further work up and advised to avoid nighttime smartphone use.  Home doses of aspirin and statin were continued.  She has had no recurrent events. 

There are very few reports of transient smartphone blindness in the literature, none in a binocular fashion. Symptoms are thought to occur due to retinal photopigment bleaching leading to decreased light sensitivity, which recovers physiologically after a few minutes.  With prolonged smartphone use at a bright setting, we postulate that this could affect both eyes simultaneously.  Unnecessary work ups and costly hospitalizations can therefore be prevented with detailed history taking.