Screen time in adults: how much is too much?

• Screen time is a fact of life for most young adults due to work or study commitments and social interactions.
• Research has shown links between high levels of screen time or near work (such as reading and study) and myopia progression, dry eye and digital eyestrain in young adults.
• Blue-light blocking coatings for spectacle lenses (glasses) can improve visual comfort in some people but not substitute for taking breaks from screen time.
• Take regular breaks, avoid holding digital devices too close to your eyes (less than 30cm) and try to limit your leisure screen time when outside of work and study time.

Lots of time spent on screens has been linked to development of vision problems, myopia, dry eyes and digital eyestrain. This can affect people of all ages, but young adults who have had myopia from their childhood or teenage years can be especially impacted.

There are strong links between spending a lot of time looking up close - whether books or screens - and myopia. Myopia is an eye condition which causes blurred far vision, and is also known as short-sightedness or near-sightedness. Myopia typically develops in childhood and then deteriorates or worsens every few to several months until the late teenage years and even into the early 20s.¹ Myopia is a significant concern to quality of life, and poses a risk to long-term eye health across adulthood.²

Research is increasingly linking digital screen and smartphone use to development of myopia in children and teenagers.^3,4 In young adults there is less available data on myopia development and progression, as most research is centered on children and teenagers who are undergoing the fastest period of myopia progression.¹ It is known that around one-third of young adults in their 20s show myopia progression, and around one in six can develop myopia in this decade after a childhood of normal vision.⁵

There is evidence that higher amounts of close-up vision work such as reading, screen time and laptop work or study are linked to myopia progression in young adults.⁶

Spending less time outdoors also appears to be linked with development of myopia in young adulthood. Being female, of East Asian ethnicity, and having a family history of myopia are also risk factors.⁵

Myopia is not the only concern when it comes to screen time. There are other effects that screen usage can have on vision and eye health. These can affect children, teenagers, younger and older adults with heavy screen usage.

1. Dry eyes: When using a screen, viewing at closer distances and when concentrating, we tend to blink less. This causes the front part of the eye that normally keeps the eye wet, healthy and comfortable (the tear film) to dry out. Dry eye symptoms have been linked with higher levels of screen use in young adults.^7,8 Dry eye can cause blurry vision, sore and red eyes, and interfere with comfortable contact lens wear. Dry eye can also affect mental health and work productivity in digital screen users.⁸ It is important that this is managed well with your optometrist or eye doctor, as ‘dry eye’ sounds simple to fix, but can often be a complex and long-term condition.
2. Digital eyestrain: Headaches, blurry vision, sore or itchy eyes are symptoms of digital eyestrain. which is estimated to affect at least 50% of digital screen users.⁹ This can be due to a combination of dry eye symptoms, undiagnosed vision problems or other issues like glare sensitivity. Post-pandemic surveys have found that over 95% of young adults experience at least one symptom related to digital device usage.¹⁰ Holding the digital device closer to your eyes and using it for longer durations increases the likelihood of suffering digital eyestrain.⁹

The best advice is to be mindful of your digital device use, especially if screen time is unavoidable in work or study. Look for alternative ways to work, learn and socialize where possible to break up the screen time.

This is a difficult question to answer as use of digital displays is a necessity for many young adults in work and study settings.

1. When at work or study, aim to take regular breaks to look away from the screen. Take some blinks, and look across the room or out of a window. This can help to reduce the risk of developing dry eye and digital eye strain.
2. When outside of work or study, try to limit leisure screen time to less than 2 hours per day. This recommendation is based on guidelines for kids and teenagers, as there are no official guidelines on this for adults.

More guidance on this is provided in the three simple rules section below.

For good general health, the World Health Organization (WHO) recommends limiting the amount of time in your day spent being sedentary or immobile, which is common during screen time. Here are the WHO physical activity guidelines for adults.

• Aim to get get 150 to 300 minutes of moderate intensity or 75 to 150 minutes of vigorous intensity aerobic physical activity across the week. That’s 20 to 40 minutes per day of moderate or 10 to 20 minutes per day of vigorous physical movement.
• Aim to do some muscle strengthening activities twice a week.

Blue-light blocking coatings on spectacle lenses (glasses) can reduce eye strain for some people, when spending a lot of time looking at back-lit screens.

There is a small amount of evidence that they can improve sleep quality in people with self-reported insomnia, but may not have an effect in those with normal sleep patterns. Claims about these coatings protecting the health of the retina have not been supported by evidence.^12,13

The best advice is to pick this type of coating if you feel more comfortable looking through it at a screen.

When it comes to eye health and reducing the risks of myopia, there are three simple rules you can consider for screen time.

1. The elbow rule. This is where you should try to keep an elbow-to-wrist distance between anything you are viewing up close, and your eyes. This helps to avoid very close viewing distances (less than 20-30cm) which are associated with increased visual effort and development of myopia.¹⁴
2. The 20/20 rule. This is where you aim to take a break from reading or screen work every 20 minutes, for 20 seconds. Look across the room for those 20 seconds, to relax the focussing muscles in the eyes before recommencing reading or screen time. This is to avoid prolonged time spent in close-up vision, which can lead to eye strain and is linked to myopia.¹⁴
3. The two-hour rule. This is aiming to limit leisure or recreational screen time, outside of study or work, to less than 2 hours per day.

Screen time is a big concern for everyone today, both for parents and for adults themselves as screen users ourselves. Read our articles on screen time in different age groups via the following links.

• Screen time for babies and toddlers: what is ok?
• Screen time for children: how much is ok?
• Screen time in teenagers: how can we manage it?

1. Hou W, Norton TT, Hyman L, Gwiazda J; COMET Group. Axial Elongation in Myopic Children and its Association With Myopia Progression in the Correction of Myopia Evaluation Trial. Eye Contact Lens. 2018 Jul;44(4):248-259. 
2. Tideman JW, Snabel MC, Tedja MS, van Rijn GA, Wong KT, Kuijpers RW, Vingerling JR, Hofman A, Buitendijk GH, Keunen JE, Boon CJ, Geerards AJ, Luyten GP, Verhoeven VJ, Klaver CC. Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia. JAMA Ophthalmol. 2016 Dec 1;134(12):1355-1363.
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9. Sheppard AL, Wolffsohn JS. Digital eye strain: prevalence, measurement and amelioration. BMJ Open Ophthalmol. 2018 Apr 16;3(1):e000146. 
10. Bahkir FA, Grandee SS. Impact of the COVID-19 lockdown on digital device-related ocular health. Indian J Ophthalmol 2020;68:2378–2383.
11. Koseki T, Kakizaki F, Hayashi S, Nishida N, Itoh M. Effect of forward head posture on thoracic shape and respiratory function. J Phys Ther Sci. 2019 Jan;31(1):63-68. 
12. Downie LE. Blue-light filtering ophthalmic lenses: to prescribe, or not to prescribe? Ophthalmic Physiol Opt. 2017 Nov;37(6):640-643.
13. Lawrenson JG, Hull CC, Downie LE. The effect of blue-light blocking spectacle lenses on visual performance, macular health and the sleep-wake cycle: a systematic review of the literature. Ophthalmic Physiol Opt. 2017 Nov;37(6):644-654.
14. Li SM, Li SY, Kang MT, Zhou Y, Liu LR, Li H, Wang YP, Zhan SY, Gopinath B, Mitchell P, Wang N; Anyang Childhood Eye Study Group. Near Work Related Parameters and Myopia in Chinese Children: the Anyang Childhood Eye Study. PLoS One. 2015 Aug 5;10(8):e0134514.