According to the American Optometric Association, anyone who exceeds two hours of computer use per day is at risk of developing computer vision syndrome. Common symptoms include eye strain, headaches, blurred vision, and dry eyes. Prolonged use of digital devices can strain the eyes due to focusing on screens at an intermediate distance. Taking regular breaks according to the 20-20-20 rule (every 20 minutes, look at something 20 feet away for 20 seconds) can help reduce eye fatigue. Proper ergonomics, lighting, managing dry eye, and addressing accommodation or refractive issues are important for prevention and treatment of computer vision syndrome.

1. Dr Divya Kesarwani
Assistant Professor, Dept of Ophthalmology
TSMMC&H,Lucknow

2.  A group of eye and vision-related problems that results from
prolonged usage of computers, tablets, e-readers, and cell phones
which causes increased stress to near vision in particlular.[*]
 It also describes the inclusion of ocular, visual and
musculoskeletal symptoms due to prolonged use of computer.[*]
*Computer vision syndrome (Digital eye strain) [Internet]. 2021 [cited
2021 May 31];Available from: https://www.aoa.org/healthy-eyes/eye-
and-vision-conditions/computer-vision-syndrome?

3.  The digital era has already revolutionized the usage of these
electronic gadgets.
 In the current scenario, the novel corona virus has really
changed it all.
 With the social distancing in practice, the new norm is to
work from home and attend classes, webinars and
consultations online.
 This indeed has increased the time spent on these electronic
and digital gadgets and is the sole contributor of
CVS.[2][3][4]

4.  These digital devices require to be held at a distance that is
intermediate between near and distance vision, thereby causing
strain on the visual system, which is designed for comfortable
near and distant vision.
 According to the American Optometric Association, as little as
two hours of continuous digital device usage per day is enough to
bring about the development of an array of eye and vision related
problems, and computer vision syndrome (CVS).
 American Optometric Association. [Online]. Available from: http://www.aoa.org/x5374.xml. [Last
cited on 2020 Aug 24].

5. The lacrimal apparatus consist of :
 Lacrimal gland
 Accessory lacrimal glands
 Lacrimal ducts
 Puncta
 Canaliculi
 Lacrimal sac
 Nasolacrimal duct

7. TEAR FILM
The tear film covers the normal ocular surface. It
comprise of the following 3 layers
1. A superficial thin lipid layer (0.11 µm) – This
layer is produced by the meibomian glands, and
its principal function is to retard tear evaporation
and to assist in uniform tear spreading
2. A middle thick aqueous layer (7 µm) – This layer
is produced by the main lacrimal glands as well as
by the accessory lacrimal glands of Krause and
Wolfring
3. An innermost hydrophilic mucin layer (0.02-0.05
µm) – This layer is produced by both the
conjunctiva goblet cells and the ocular surface
epithelium

8.  Keeps the cornea and conjunctiva moist.
 Provides nourishment to the corneal epithelium.
 Washes away debris and noxious irritants.
 Prevent infection due to presence of antibacterial substance.
 Facilitates movement of the lids over the globe.

9.  Extraocular symptoms - Shoulder pain, neck pain, neck
stiffness, headache and backache.
 Visual symptoms - Blurred vision, double vision, presbyopia
and slowness of focus change.
 Ocular - Internal symptoms (Asthenopic) - Eye strain, ache in
the eye, ache around the eyes, tired eyes and sore eyes.
 Ocular - External symptoms - Burning, dryness, redness, gritty
sensation, tearing and irritation.

10.  Characters (pixels) on computer screen do not have well defined
edges. They are brightest at the center and diminish in intensity
towards the edges.
 This makes it very difficult for eyes to maintain focus.
 Extensive focusing does not give much opportunity to the eye
muscles to move and this leads to eye strain, burning,
tired – eyes feeling.

11.  Computer users have a very fixed posture.
 Constant gazing at a near distance at the monitor (which leads to
convergence fatigue).
 The upper body remains fixed for very long period of time.
 The eye muscles do not get much opportunity to move.
 Uncorrected visual defects

12.  In children, symptoms with a prolonged history of screen exposure include
 Reduced attention span,
 Poor behaviour,
 Irritability, dry eyes,
 Ocular irritation,
 Eye strain, headache,
 Neck pain and shoulder pain.[5]

13. 1) Refractive errors
2) Abnormal binocular interaction
3) Accomodation abnormality: The triad of near reflex when an
individual focuses on near objects: Accommodation, miosis,
and convergence.
4) Uncorrected presbyopia
5) Dry eye or abnormal ocular surface

14.  Reduced blinking
 Larger palpebral fissure while viewing a screen in horizontal gaze
compared to while reading in downgaze (increased exposed area of the eye)
 Higher age and Female - especially postmenopausal women
 Environment- air conditioner, dry air [low humidity], air-borne particles
including dust, the toner of digital printer, building contaminants, ventilation
fans, etc.
 Contact lens use and Cosmetics over the eyelid
 Lid condition- anterior blepharitis, meibomian gland dysfunction
 Medications: preservatives of topical medication, anticholinergic drugs and
diuretics

15.  Blue light: Most digital screens (especially LED - light-emitting diodes) are
known to emit blue light (400-500nm).]
 Circadian rhythm depends on exposure to light, especially blue light. Melatonin
is secreted at night and plays a crucial part in the sleep cycle in humans.
Intrinsically photosensitive retinal ganglion cells (pRGC) play a critical role in
the circadian rhythm by sending messages to the pineal gland. These cells have
the highest sensitivity at 482nm. [21] Thus, presentation of blue light not in sync
with the sun may alter the coupling of the biological clock with the
geographical clock of that area resulting in abnormal circadian rhythm and
sleep pattern.
 An association with age-related macular degeneration has been suggested,[22]

16.  Various attributes of the display may predispose to CVS. These include
• Lower Resolution of the screen-
 Fewer dots per inch (dpi) and fewer pixels
 For significantly larger characters readability was noted to be similar in
low-resolution screen (720 x 350 pixels) and higher resolution screen
(1664 x 1200 pixels).[24]
 However, readability was better with a higher resolution screen while
reading very small characters. [24]
• Poor Image stability

17. High brightness and high contrast may cause blurring of
characters
Words with all capital letters are difficult to interpret compared
to sentence case
Less than one character space between lines
Less than ½ character space between words
Light characters against a dark background (negative display
polarity) should be avoided.
Dark character against a light background (positive display
polarity) is recommended.[25][26]

18.  In the digital screens, the screen is repainted at a frequency measured in Hz.
 Critical flicker fusion frequency (CFF) is the refresh rate at which the human visual System
fails to recognize the flickering nature of the screen and the screen appears to be constantly
illuminated.
 The normal value of CFF is 30-50Hz.
 Low refresh rates can cause fatigue, headache, annoyance reduced accommodation, increased
blink interval, reduced blink time and reduced reading speed.[4]
 Standard desktop and laptop monitor refresh rate is 60Hz or 64Hz, but newer monitors
have higher refresh rates 120Hz, 144Hz or 240Hz.
 Improper lighting condition aggravates CVS that include:
◦ Surrounding light (like window behind the monitor)
◦ Reflection

19. 1. Radiation: VDTs are known to emit infrared radiation and the visible spectrum of light
2. Cataracts
3. Pregnancy: ] A meta-analysis excluded significant excess risk of for spontaneous
abortion, low birth weight and congenital malformations due to the use of VDT.[31]
4. Sleep and circadian rhythm
 Blue light plays a crucial role in the circadian rhythm. It has been shown that performing
an exciting VDT task with a BD (bright display) suppresses the nocturnal changes in
melatonin concentration and other physiological indicators of human biological clocks.
 Specifically, the use of digital devices just before sleep may alter sleep patterns.[34]

20. 5) Neuro-Psychiatric issues:
 National research council noted that screens with very low refresh rates (8-
14Hz) can be epileptogenic.[4]
 Exposure to LED light at night may cause misalignment of social and
biological rhythms and sleep loss.[36]
 This, in turn, may be linked to daytime sleepiness, fatigue, poor academic
achievement and behavioral problems in adolescents.[36]
 Increased risk of job burnout and occupational stress was noted in internet staff
working on VDT for more than 11 hours daily.[37]

21. 6) Development in child
 Childhood obesity probably due to less physical activity, more calorie intake,
and reduced metabolic rate.[38]
 Altered sleep time, hypertension, dyslipidemia and cardiovascular disease.[39]
 Though home computer use may slightly improve academic performance, high
screen time has been linked to loneliness and depression.[40]
 Affects socio-emotional and cognitive development, promote depression, anxiety
and irritability ultimately leading to poor academic performance.[41]
 Violent video games may increase aggression and may affect the child's ability
to distinguish reality from simulation.[40]
 Effects on refractive error (especially myopia), [42] reduced bone density,
attention deficit hyperactivity disorder (ADHD), difficulty to focus and the
tendency for depression and suicidal thoughts.[40][43]

22. According to AOA (American Optometric
Association), anyone who exceeds two
hours of computer use a day is at a risk for
CVS.

23. 1) Predisposing factors
2) Comprehensive Ophthalmic examination: visual acuity, refraction,
intraocular pressure, pupillary examination, examination of ocular adnexa
and ocular motility, slit-lamp examination of the anterior segment, and
examination of the posterior segment.
3) Specifically, the lids and ocular surface should be examined thoroughly.

24. 1)Accommodation and vergence parameters
 Squint evaluation and examination or vergence abnormalities should also be performed.
2)Critical flicker fusion frequency (CFF): CFF is the frequency at which the human
visual system perceives a flickering light as continuous non-flickering light. ]
3)Blinking
4)Pupil size: A large pupil may cause visual fatigue due to reduced depth of focus.[49]
 Visually demanding tasks including computer work may cause an increase in pupil
size.[50]
 Around 1/3rd of individuals can have pupillary constriction after completion of such
demanding task or intense near work which might be due to spasm of the pupillary
sphincter and ciliary muscle.[51][52]

25.  Multiple questionnaires are available to determine the severity of CVS.
Some of the questionnaires include:
1) Dry Eye Questionnaire (DEQ-5)
2) Questionaire by Hayes and colleagues (has 10 items)[53]
3) Visual fatigue scale
4) Computer vision symptom scale (CVSS17)
5) CVS questionnaire (CVS-Q)[54]

26. 1) Ergonomics: The workplace should be ergonomically designed. It reduces
discomfort and increases productivity.[55][56]
 A humidifier: to improve the moisture of the air.
 To reduce eye strain, the room lighting may be adjusted and the contrast of the
computer screen may be increased.
 Matte screen filter can be considered.
 Position the monitor so that the looks slightly down and not straight ahead or up.[59
 ]Studies have shown that a viewing distance of 90 cms and a slightly downward
gaze of 10 degrees reduced ocular discomfort.[60]

27.  Top of the monitor should be at or just below eye level. Higher screen causes strain in the neck and
upper trapezius muscles.[58][4]
 Head and neck should be balanced and in line with the torso.
 Shoulders should be relaxed.
 Elbows should be close to the torso and supported.
 Lower back should be supported.
 Wrists and hands should be in line with the forearms.
 There should be adequate room for the keyboard and the mouse.
 The feet should be lying flat on the floor.
 Sit at arm's length from the computer screen. A shorter distance may cause eye strain.

28. 2)Lighting at workspace
 Lights causing glare should be limited.
 Antiglare filter reduces contrast, reflection, and glare but may not reduce asthenopia.[4]
3)Breaks in between work[27]
 Duration of exposure to digital screen should be limited and dependence on smartphones should be
reduced, if possible.
 This relaxes and restores the accommodative system reducing digital eye strain. According to the
famous 20-20-20 rule, every 20 minutes, an individual should take the eye off from the screen for
about 20 seconds and look at a distant object (situated at 20 feet away).[61]
 A quick walk or stretching or workstation exercise in between work can give relief to the strained
and fatigued body muscles, reduce the monotony of the work, and provide possible relaxation and
reduce discomfort.[63]
 The National Institute for Occupational Safety and Health (NIOSH) noted that frequent short
breaks in work reduces discomfort and improves productivity compared to typical morning and
afternoon breaks for 15 minutes.[4]

29.  Multiple softwares (user discretion is advised) are available for reminding the user to take a break during continuous work of computers:
 http://eyeleo.com/download
 http://iamfutureproof.com/tools/awareness/#
 https://chrome.google.com/webstore/detail/eyecare-protect-your-visi/eeeningnfkaonkonalpcicgemnnijjhn?hl=en
• Every 20 minutes…
• Take a 20 second break…
• And look at something 20 feet
away.

30. 4) Management of vergence or accommodation problems
 Associated problems with binocular interaction and accommodation should be
managed
5) Glasses
 Uncorrected cylinder is particularly a problem in individuals using over the counter
reading glasses.
 The glasses should be prepared after carefully measuring the interpupillary distance.
 Contact lenses might worsen CVS and thus glasses may be preferred for computer
work.
6)Blinking
 Softwares are available to remind the user to blink or take micro breaks during work.
 The American Optometry Association recommends taking rest as per the 20-20-20
rule and at least 15 minutes after each continuous 2 hours of computer work.
 Blink training may be helpful to reduce the symptoms of CVS.[1]

31. Computer users should make a conscious
effort to blink more often:
 They should try out the suggested formula
20: 20: 20
 Every 20 mins: for 20 seconds: blink 20
times
OR
BLINK EVERYTIME U HIT THE
‘’ENTER’’ KEY OR MOUSE CLICK

32. 7) Management of dry eye disease
 Blepharitis and meibomian gland dysfunction (MGD) should be managed properly and
lid hygiene should be maintained.
 Modifications to improve humidity and ergonomic design of the workplace should be
planned to reduce dry eye as mentioned under ergonomics.[2][60]
 Lubricating drops may reduce dry eye symptoms including dryness, irritation, ocular
discomfort, tiredness and difficulty in focusing though complete resolution may not
occur.[3][66][67] (do not improve the blink rate)
 Blinking exercises every 20 minutes by closing the eyes for 2 seconds, opening and
again closing for 2 seconds followed by squeezing for 2 seconds showed positive
effect on alleviating dry eye symptoms and signs.[69]
 Polyvinyl alcohol and dextran : for evaporative dry eyes but with less evidence.
 Omega 3 fatty acids were shown to improve dry eye symptoms.

33. 8) Special glasses:
1) Blue cut lenses/Blue blocking lenses: blocks the short-wavelength visible light (blue light)
lower the reduction of CFF  reduce eye fatigue.[46]
 However, a recent randomized control trial noted no improvement of CVS with blue-blocking
lenses.[72]
 According to the American Academy of Ophthalmology 'There is no scientific evidence that
the light coming from computer screens is damaging to the eyes. Because of this, the
Academy does not recommend any special eye wear for computer use.'
2) Microenvironment glasses: may increase the humidity and reduce evaporation of tear film thus
reducing the dry eye symptoms. It may also protect from particulate matters/irritants in the air.
 Promote circadian rhythm
 The use of VDT (blue light) especially before sleep time should be reduced to avoid alteration of
the sleep cycle and circadian rhythm.
Software (F.lux, Twilight 🌅 Blue light filter for better sleep) are available to change the color of the desktop screen according to the
time of the day and thus to possibly promote circadian rhythm. Future research is needed to find out the exact utility of such software.

34.  Computer vision syndrome is the emerging and worrisome ocular condition
affecting both young and old equally due to increased usage of computer both at
home and at work.
 There is a correlation between ocular symptoms such as pain, redness, dryness,
blurring of vision, double vision and other head and neck sprains and computer
usage.
 Modification in the ergonomics of the working environment, patient education
and proper eye care are important strategies in preventing computer vision

35.  Prevention remains the main strategy in managing computer vision
syndrome.
 To make people aware to not become slaves to the digital devices as
these may impact our future generations in an irreversible and
dangerous way.

36. Happy Computing!