Children at school should be able to learn and adults to work safely with clear single sight. Visual fatigue and binocular dysfunction from screen and device use may resolve with glasses. However, resetting the binocular vision eye movements and focus may be necessary to fully reduce symptoms. It is also recommended to specifically improve habits or choices when viewing screens.
Accrued time viewing and interacting with screens on a daily basis (phone, computer, laptop, TV, xbox and tablet) at school & home throughout the week can generate visual fatigue. This includes scrolling through images and is not limited to reading print. These are recommended guidelines for screen viewing for people of all ages.
Screens
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The preferred minimum screen size is a full size tablet (A5 paper sized screen) but many people will be using their phones and need to consider what information can be viewed on a larger screen. This applies to print, articles, images, emails and communications such as Instagram and Facebook.
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Preference for lap top and PC screens for reading articles and completing online activities.
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Optimise the device screens by: Increasing the size of all tool bars; enlarge images and all active screen text print; enlarge images and articles whenever possible; consider reverse background to black and choosing a text style that is large and easy to read.
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Be aware of how to alter brightness settings so that these are the minimum level for the light conditions throughout the day and evening (some screens may automatically optimise this).
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Use blue filter settings where available.
Most scrolls move print upwards and this creates the effect of horizontal lines moving up. This causes an optokinetic effect where vision moves with the expectation that the eyes are moving outward to a distant object and diverge in the process. Once the scroll stops the eyes must converge to the print to focus the words. Repeating this to fill in documents or find specific paragraphs repeatedly through the day is an issue. To help reduce fatiguing the fusion and focus reserves, slow the scroll in the setup for touch screens; use a touch and finger slide to move the writing in sections; enlarge tool bars and print for less focus effort.
Scroll
Considerations for all devices
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Holding distance for hand held devices should be no closer than the length of the forearm from nose to surface.
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View screens with good posture seated or standing (i.e. not lying on the stomach with the view in an upward gaze, not with the screen on the chest, nor lying sideways).
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Ensure a side lamp, at least, is on at all times when viewing any digital screen, including phones, ipads, laptops, PCs, and TVs. This promotes visual stability by including peripheral vision with centrally lit viewing.
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Regular breaks are required considering the age and tiredness of children and elderly. For adults ¾ hour viewing a screen and 15 minutes away is advisable throughout a day (this from data entry studies from the 1980s).
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Standing and walking around your office chair is a break because when we do this the brain resets the eyes alongside the body posture. Walking to a new space to continue to work with a laptops also provides a break.
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This list is not exhaustive and you can add anything that comes to mind.
Development
Children's visual development is occurring throughout childhood and is not performing as adult vision systems do until growth has settled (this is over 20 years of age for most boys and late teens for girls). It is known that the vision adapts to persistent viewing past 20 minutes of reading. If this is draining on the vision then tiredness and fatigue would follow. This is a good time for a break of a similar time (likely to suit only younger children). The option to stand and shift to continue tasks within 1 hour of screen use helps keep vision available to use.
"Our visual world is generated from a complex group of light, movement and expectation. When these do not align we experience discomfort and confusion. As the optometrist I enjoy working through these more difficult and thought provoking problems and guiding people through individual programs to address these".