Computer Vision Syndrome (Digital Eye Strain)

Key Points at a Glance

Key Points of This Disease

• Computer Vision Syndrome (CVS) / Digital Eye Strain (DES) is a group of eye, visual, and musculoskeletal symptoms caused by prolonged use of digital devices.
• The global prevalence is about 66%, rising to 74% during the COVID-19 pandemic ⁹⁾¹³⁾.
• The main mechanisms are three: ocular surface damage due to abnormal blinking, accommodative and vergence dysfunction, and environmental factors (lighting, ergonomics) ¹⁾.
• The 20-20-20 rule (every 20 minutes, look at something 20 feet away for 20 seconds), improving the work environment, and artificial tears are basic measures.
• The effectiveness of blue-light-blocking lenses for DES is not supported by current evidence ¹⁾.
• Proper refractive correction and optimization of the work environment are the pillars of prevention.

1. What is Computer Vision Syndrome (Digital Eye Strain)?

Computer Vision Syndrome (CVS) is a complex of eye, visual, and musculoskeletal symptoms caused by prolonged use of digital devices. In recent years, the term “digital eye strain (DES)” has been recommended as a broader concept not limited to computers ¹⁾⁸⁾.

The American Optometric Association (AOA) defines this condition as “a group of eye and vision-related problems that result from prolonged use of computers, tablets, e-readers, and cell phones” ¹⁾. Meanwhile, the Tear Film & Ocular Surface Society (TFOS) proposes a more specific definition: “the development or exacerbation of recurrent ocular symptoms and signs specifically related to viewing digital device screens” ¹⁾.

A characteristic of DES is its transient nature. Symptoms generally improve when device use is discontinued ⁸⁾. However, in modern society where digital devices are essential, symptoms recur daily, making it an important public health issue ³⁾.

Q What is the difference between CVS and DES?

A

CVS is an older term limited to “computers.” DES is recommended as a broader concept encompassing all digital devices such as smartphones, tablets, and VR headsets. Clinically, they are nearly synonymous.

2. Main Symptoms and Clinical Findings

Subjective Symptoms

Symptoms of DES are nonspecific and diverse, broadly classified into four categories⁸⁾.

Asthenopia

Eye fatigue/heaviness: worsens with prolonged near work

Blurred vision: can occur both for distance and near

Eye pain/discomfort: perceived as persistent dull pain

Diplopia (rare): appears when accompanied by convergence insufficiency

Dry Eye-Related Symptoms

Dryness sensation: mainly due to decreased blink rate

Foreign body sensation/burning: caused by tear film breakup

Tearing: due to reflex lacrimation

Photophobia: appears with ocular surface damage

Exacerbation of Existing Eye Diseases

Manifestation of uncorrected refractive errors: mild astigmatism or presbyopia amplifies symptoms

Headache: especially common in the frontal region

Difficulty focusing: Particularly noticeable in presbyopia

Musculoskeletal symptoms

Neck and shoulder pain: Caused by poor posture

Lower back pain: Related to improper screen positioning

Wrist and finger pain: Occurs with prolonged keyboard use

The most frequent symptoms are headache, eye strain, dry eyes, blurred vision, and neck/shoulder pain⁴⁾. Using devices at a distance of less than 50 cm from the screen increases the frequency of headaches, with smartphone use being particularly risky⁷⁾.

Clinical findings

The following objective findings have been reported in DES:

Changes in blinking: During digital device use, blink rate decreases and incomplete blinks increase¹⁾⁴⁾. Reduced blink rate promotes tear evaporation and causes ocular surface dryness.

Tear abnormalities: Shortened tear break-up time (TBUT) is observed⁷⁾. Increased tear osmolarity has also been reported, indicating evaporative dry eye pathology.

Changes in accommodation and vergence: After prolonged use, decreased accommodative amplitude and recession of the near point of convergence are observed⁷⁾. In children, acute acquired comitant esotropia (AACE) has been reported⁷⁾.

Intraocular pressure fluctuations: Mild increases in intraocular pressure during smartphone use have been reported⁷⁾. It has also been noted that IOP may rise in patients with normal-tension glaucoma under low-light conditions.

Q How can I tell if I have DES?

A

If you repeatedly experience dry eyes, eye strain, blurred vision, or headaches after prolonged use of digital devices, and these symptoms improve when you take a break, DES is likely. It can be assessed using standardized questionnaires such as the CVS-Q (Computer Vision Syndrome Questionnaire). If symptoms persist, it is advisable to see an ophthalmologist to check for refractive errors or dry eye.

3. Causes and risk factors

The development of DES involves a complex interplay of individual, environmental, and device-related factors.

Systematic reviews and meta-analyses have quantified the odds ratios of the following risk factors¹¹⁾.

Risk factor	Odds ratio
Short viewing distance	4.24
Poor ergonomics	3.87
Poor posture	2.65
No breaks	2.24
Prolonged use	2.02
Female sex	1.74

Individual factors: Uncorrected refractive errors (especially astigmatism of 0.50–1.00 D) amplify DES symptoms ⁷⁾. Presbyopic patients require appropriate refractive correction for near work. Women have a higher prevalence of DES than men (69% vs 60%) ¹³⁾.

Environmental factors: When the screen is positioned higher than eye level, the exposed ocular surface area increases, worsening dry eye symptoms ¹⁾. Humidity below 40%, high temperature environments, and direct exposure to air conditioning promote tear evaporation ⁷⁾. Regarding lighting, 200 lux or more is considered appropriate for VDT workstations ⁷⁾.

Device factors: Insufficient screen resolution, inappropriate brightness, and glare worsen symptoms ⁷⁾. Smartphones have the highest CVS severity due to their small screen and close viewing distance ⁷⁾.

Prevention and Daily Care

Here are some tips to prevent digital eye strain.

20-20-20 rule: It is effective to look at something 20 feet (about 6 m) away for 20 seconds every 20 minutes.

Adjust screen position: Place the top of the screen below eye level and maintain a distance of 50–100 cm.

Optimize work environment: Reduce the difference in brightness between room lighting and the display, and prevent glare.

Conscious blinking: Blinking decreases while staring at a screen. Make a conscious effort to blink fully.

Appropriate refractive correction: Uncorrected astigmatism or presbyopia worsens DES. If needed, get a prescription from an eye doctor.

Q After how many hours of use per day do symptoms begin to appear?

A

Symptoms may appear after 2 hours of continuous use. The risk of dry eye increases with 4 hours or more of use, and becomes even more pronounced after 8 hours. However, individual differences are large, and those with pre-existing refractive errors or dry eye may develop symptoms in a shorter time.

4. Diagnosis and Examination Methods

The diagnosis of DES is mainly based on evaluation of clinical symptoms. Although there are no established global diagnostic criteria, the following approaches are recommended ⁸⁾.

Assessment by questionnaire: Standardized questionnaires include the following ⁴⁾⁸⁾.

• CVS-Q (Computer Vision Syndrome Questionnaire): Evaluates the frequency and severity of 16 symptoms; a score of 6 or higher diagnoses DES.
• CVSS17 (Computer Vision Symptom Scale): A 17-item scale based on the Rasch model.
• DESQ (Digital Eye Strain Questionnaire): A new questionnaire covering general digital device use.

Objective tests: The following are used for objective assessment of visual fatigue ¹⁾.

• Critical flicker fusion frequency (CFF): A quantitative indicator of visual fatigue.
• Blink analysis: Allows evaluation of blink rate, blink duration, and incomplete blinks.
• Pupillary response: Can capture changes associated with fatigue.

Ophthalmic evaluation: The following tests are performed for DES assessment, including differential diagnosis ²⁾.

• Tear film tests: TBUT, Schirmer test, tear osmolarity, non-invasive tear break-up time.
• Accommodation and convergence function tests: Assessment of accommodative amplitude, near point of convergence, and accommodative response.
• Refraction test: Detection of mild refractive errors or presbyopia.
• Differential diagnosis: Exclusion of conditions with similar symptoms such as allergies or infections.

5. Standard Treatment

Management of DES is based on identifying the cause and individualized treatment. Treatment is broadly divided into environmental adjustments, ophthalmic interventions, and nutritional interventions.

Environmental adjustments and behavioral changes

20-20-20 rule: The most widely recommended break method ¹³⁾

Optimize screen position: Set the top of the screen 15–20 degrees below eye level ⁷⁾

Improve lighting: Reduce glare and balance brightness between screen and surroundings

Use a humidifier: Using a desktop humidifier for 1 hour has been reported to improve TBUT and eye comfort ⁷⁾

Ophthalmic interventions

Refractive correction: Prescribe full correction for the appropriate working distance ¹⁾

Artificial tears: Used for dry eye symptoms on the ocular surface ⁴⁾

Blinking exercises: Repeat a set of closing eyes for 2 seconds × 2 times + forceful closure for 2 seconds ⁷⁾

Accommodation and convergence training: Consider if binocular vision abnormalities are present

Nutritional intervention: According to a systematic review by TFOS, oral omega-3 fatty acid supplementation is the only option with high-quality evidence for efficacy in managing DES ²⁾. It improves dry eye symptoms on the ocular surface through antioxidant and anti-inflammatory effects ¹²⁾. Xanthophyll macular carotenoids (lutein, zeaxanthin) have been reported to potentially improve visual performance and cognitive function ¹²⁾. Anthocyanins are also suggested to have protective effects against visually induced cognitive stress and digital eye strain ¹²⁾.

About blue light blocking lenses

LED displays emit blue light (380–500 nm), but current evidence is insufficient to support that blue light blocking lenses reduce DES symptoms ¹⁾⁸⁾. Double-blind randomized controlled trials have not confirmed significant effects. Approaches other than blue light blocking are recommended for DES management.

Q Are blue light blocking glasses effective for DES?

A

Current randomized controlled trials have not provided evidence that blue light blocking lenses significantly reduce DES symptoms. The main causes of DES are abnormal blinking, accommodative fatigue, and environmental factors, not light wavelength characteristics. For prevention, the 20-20-20 rule, appropriate refractive correction, and optimization of the work environment should be prioritized first.

6. Pathophysiology and detailed mechanisms

Three main mechanisms are involved in the development of DES¹⁾.

1. Blink abnormalities and ocular surface disorders

During digital device use, blink rate decreases and incomplete blinks increase¹⁾⁴⁾. The normal blink rate is 15–20 times per minute, but it significantly decreases while gazing at a screen. Reduced blink rate and incomplete blinks promote tear evaporation and increase tear osmolarity. This leads to ocular surface dryness and inflammation, causing dry eye-like symptoms. Additionally, horizontal gaze (when using a desktop screen) widens the palpebral fissure compared to downward gaze, increasing the exposed ocular surface area⁸⁾.

2. Accommodative and vergence dysfunction

Near use of digital devices requires sustained accommodative effort. Prolonged near work causes a decrease in accommodative amplitude, recession of the near point of convergence, and increased accommodative lag⁵⁾⁶⁾. These changes lead to increased exophoria, convergence insufficiency, and fixation disparity, resulting in blurred vision, diplopia, and eye strain. In children, prolonged smartphone use has been reported as a risk factor for AACE (acute acquired comitant esotropia)⁷⁾.

3. Environmental factors and musculoskeletal disorders

Inappropriate environmental factors such as screen position, angle, lighting, and glare force the user to maintain unnatural postures⁸⁾. Increased neck flexion angle exacerbates upper trapezius muscle fatigue and neck pain⁷⁾. Screens that are too high or too low can cause low back pain and abnormal posture. Smartphone use tends to result in a particularly large neck flexion angle.

7. Latest research and future perspectives

Global prevalence trends: According to meta-analyses, the pooled prevalence of DES is 66% (95% CI: 59–74%), making it a highly common condition affecting two out of three people¹³⁾. During the COVID-19 pandemic, due to the surge in remote work and online learning, the prevalence rose to 74% (95% CI: 66–81%)⁹⁾.

Population	Prevalence
World (normal times)	66%13)
During COVID-19	74%9)
Non-students (during COVID)	82%9)
Students (during COVID)	70%9)

Impact on children: DES has been called a “shadow pandemic” in children¹²⁾. A study in India found that average screen time doubled from 1.9 hours before COVID to 3.9 hours, and the prevalence of DES in children reached 50.2%¹²⁾. Age 14 or older, male sex, and device use over 5 hours per day were identified as risk factors.

Advances in nutritional intervention: Supplementation with macular carotenoids (lutein, zeaxanthin, and meso-zeaxanthin) has shown improvements in visual performance and cognitive function, and is expected as an adjunctive approach for DES¹¹⁾. Omega-3 fatty acids are positioned as the management with the highest level of evidence in the TFOS systematic review²⁾.

Emergence of new technologies: VR (virtual reality) head-mounted displays impose a different near visual load compared to traditional screens, raising concerns about effects on accommodation and vergence. Development of DES monitoring and prevention systems using AI and wearable devices is also progressing.

Medical Disclaimer

The content of this article is not a substitute for diagnosis or treatment by a medical professional. If you experience any eye abnormalities, consult an ophthalmologist.

Q How can DES be prevented in children?

A

It is recommended to limit continuous screen time (preferably within 2 hours), practice the 20-20-20 rule, maintain an appropriate distance from the screen, and ensure sufficient outdoor activity. Education and health authorities are also called upon to establish guidelines for e-learning time. It is important for parents to manage usage time and avoid excessive device use from early childhood.

8. References

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2. Downie LE, Craig JP, Wolffsohn JS, et al. TFOS Lifestyle: Impact of the digital environment on the ocular surface – Management and treatment. Ocul Surf. 2023;30:253-285.

3. Kahal F, Al Darra A, Torbey A. Computer vision syndrome: a comprehensive literature review. Future Sci OA. 2025;11(1):2476923.

4. Pucker AD, Kerr AM, Sanderson J, Lievens C. Digital Eye Strain: Updated Perspectives. Clin Optom. 2024;16:249-261.

5. Barata MJ, Aguiar P, Grzybowski A, Moreira-Rosário A, Lança C. A Review of Digital Eye Strain: Binocular Vision Anomalies, Ocular Surface Changes, and the Need for Objective Assessment. J Eye Mov Res. 2025.

6. Kaur K, Gurnani B, Nayak S, et al. Digital Eye Strain- A Comprehensive Review. Ophthalmol Ther. 2022;11:1655-1680.

7. Pavel IA, Bogdanici CM, Donica VC, et al. Computer Vision Syndrome: An Ophthalmic Pathology of the Modern Era. Medicina. 2023;59:412.

8. Mylona I, Glynatsis MN, Floros GD, Kandarakis S. Spotlight on Digital Eye Strain. Clin Optom. 2023;15:29-36.

9. León-Figueroa DA, Barboza JJ, Siddiq A, et al. Prevalence of computer vision syndrome during the COVID-19 pandemic: a systematic review and meta-analysis. BMC Public Health. 2024;24:640.

10. Lema アカントアメーバ角膜炎, Anbesu EW. Computer vision syndrome and its determinants: A systematic review and meta-analysis. SAGE Open Med. 2022;10:20503121221142400.

11. Lem DW, Gierhart DL, Davey PG. Can Nutrition Play a Role in Ameliorating Digital Eye Strain? Nutrients. 2022;14(19):4005.

12. Bhattacharya S, Heidler P, Saleem SM, Marzo RR. Let There Be Light-Digital Eye Strain (DES) in Children as a Shadow Pandemic in the Era of COVID-19: A Mini Review. Front Public Health. 2022;10:945082.

13. Anbesu EW, Lema アカントアメーバ角膜炎. Prevalence of computer vision syndrome: a systematic review and meta-analysis. Sci Rep. 2023;13:1801.