Transient Smartphone Blindness (TSB) is a temporary loss of vision in one eye that occurs when looking at a smartphone while lying on one’s side in a dark environment.
When first reported in academic literature, all cases involved individuals who used their smartphone while lying on their side in the dark before sleep and noticed vision loss for several minutes after turning off the screen. The cause was determined not to be an organic disease but a normal physiological phenomenon of interocular light adaptation difference.
It is clinically important because it must be differentiated from serious conditions such as TIA and multiple sclerosis. It has also been associated with digital eye strain (DES), including dry eye 1).
Yes, it is possible. A phenomenon has been reported where, after looking at a smartphone in a dark room while covering one eye with a pillow or similar object, the covered eye temporarily loses vision when the screen is turned off. This is due to normal light adaptation differences and is not a disease.
The typical onset situation and symptom characteristics are as follows.
Even if tests are performed at the time of onset, all findings are within normal limits.
Onset Conditions
Side-lying in a dark place: One eye is physically blocked by a pillow or arm.
Smartphone use: Gazing at a bright screen for several minutes or more.
After turning off the screen: The timing when vision loss appears in the covered eye.
Characteristics of Symptoms
Unilateral and transient: Only in the covered eye, recovery within seconds to minutes.
Painless: No eye pain or headache.
Recurrent: May recur under the same circumstances.
Test Findings
Visual acuity and intraocular pressure: Within normal range.
Fundus and MRI: No organic abnormalities.
Electroretinogram: A temporary decrease in B-wave amplitude may be observed in the covered eye.
When one eye is physically covered and the other eye gazes at a bright smartphone screen for a long time, a large difference in the degree of light adaptation occurs between the two eyes.
Immediately after turning off the screen, the covered eye cannot instantly adapt to the dark environment, and the person experiences temporary vision loss. This phenomenon is a normal physiological response and does not cause damage to the retina or nerves.
Digital eye strain (DES) is a common complication of prolonged smartphone use and has been suggested to be associated with transient vision loss1).
Diagnosis is established through a detailed patient history. It is most important to confirm the typical onset situation (dark place, side-lying position, one eye covered, smartphone use).
Diseases that require differential diagnosis are listed below.
| Disease | Characteristics of Vision Loss | Other Findings |
|---|---|---|
| Transient smartphone blindness | Unilateral, seconds to minutes | Normal examination |
| Amaurosis fugax | Unilateral, seconds to 30 minutes | Vascular pathology |
| NA-AION | Persistent, unilateral | Optic disc edema2) |
| Scintillating scotoma | Binocular, positive symptoms | History of migraine |
TSB always has a typical onset situation (dark place, side-lying, covering one eye, smartphone use) and recurs under the same conditions. It is common in young individuals without neurological symptoms or vascular risk factors. If TIA or transient monocular vision loss is suspected, carotid ultrasound or cardiac evaluation is necessary, but if the situation matches TSB, excessive testing can be avoided.
TSB is a normal physiological response and does not require treatment. The prognosis is good, and it does not cause organic visual impairment.
To prevent recurrence, the following lifestyle modifications are effective.
Environmental Adjustments
Use in bright places: Avoid using smartphones in dark places.
Use indirect lighting: Turn on a nearby light when using before bedtime.
Posture Improvement
Use while lying on your back or sitting: Avoid side-lying positions where one eye is covered.
Keep both eyes open: Adjust posture to avoid covering one eye.
Device Settings
Use dark mode: Lowering screen brightness reduces adaptation differences 1).
Automatic brightness adjustment: Use brightness settings that match the surrounding light.
Dark mode is expected to reduce screen brightness and minimize the difference in light adaptation between the two eyes in dark environments 1). However, the most reliable prevention is to avoid covering one eye while lying on your side.
The core mechanism of this condition lies in the difference between bleaching and regeneration of rhodopsin, the photopigment in retinal photoreceptors.
Comparison of the covered eye and the viewing eye is shown below.
| State | Covered eye (affected eye) | Viewing eye |
|---|---|---|
| Using smartphone | Dark adapting | Light adapted, rhodopsin bleached |
| Immediately after screen off | Delayed recovery → vision loss | Normal dark adaptation |
Rhodopsin is isomerized from 11-cis-retinal to all-trans-retinal by light (bleaching), and is resynthesized back to rhodopsin in the dark. This resynthesis takes several minutes.
In the viewing eye, prolonged exposure to bright light causes extensive bleaching of rhodopsin, but dark adaptation proceeds normally in the dark. On the other hand, although the occluded eye was placed in the dark, the dark adaptation circuit is delayed for some reason, and when suddenly exposed to darkness after the screen is turned off, it cannot immediately exhibit visual function.
Electroretinography has confirmed a temporary decrease in the B-wave amplitude of the occluded eye, which serves as objective evidence of temporary suppression of photoreceptor function via bipolar cells.
The mechanism is fundamentally different from NA-AION (non-arteritic anterior ischemic optic neuropathy); in TSB, ischemia, inflammation, and structural damage are not involved at all 2).
Research is progressing on the effects of blue light emitted from smartphone screens on photoreceptor cells. Regarding the long-term effects of blue light cut filters and dark mode on visual function, sufficient evidence has not yet been accumulated 1).
DES is a group of symptoms associated with prolonged use of smartphones and PCs, and transient visual fluctuations are increasingly being recognized as one of its symptoms. The TFOS (Tear Film & Ocular Surface Society) DES report suggests an association between digital device use and transient vision loss, but long-term epidemiological data are lacking 1).
At present, there are no clear preventive guidelines. If long-term research on DES accumulates, evidence-based guidelines on recommended posture and brightness settings when using smartphones may be developed 1).
