How to safely use a monitor and avoid visual problems.
ITALY’S REGULATION ON DISPLAY SCREENS AND OTHER USEFUL TIPS
Legislative Decree 626/94, which was later integrated to the Consolidated Law on Health and Safety in the Workplace (D.Lgs. 81/2008, subsequently integrated and amended), indicates all mandatory characteristics of a workplace that an employer must enforce to ensure maximum comfort. This legislation requires compliance with some important rules regarding eye health , which can also be applied when using a computer at home. They concern, in particular:
● The recommended visual distance when working with standard screens (15-17 inches) should vary from 50 cm to 70-80 cm. The greater the size of the screen, the greater the distance should be.
● Place the keyboard on a workstation in such a position that there is adequate space to rest your forearms.
● The height of the screen should be in a position that is lower than the user’s eye-level (by 15-20 degrees) and, if possible, at a distance of at least 1.5 metres from any window.
● No light source should be positioned within a 30 degree range of your gaze, so to avoid being dazzled or disturbed.
● The quality of vision. It’s important to wear any glasses prescribed by an ophthalmologist when working in front of a screen. Inform your ophthalmologist that you work with a computer screen, so that they can consider this in the choice of any required glasses.
● The contrast and brightness of the screen must be well regulated so that it doesn’t cause any discomfort to your eyes. Do some tests to find the optimal conditions to comfortably carry out your computer-based activities.
● Avoid reflections on the screen that make reading difficult. In general the screen should be placed at 90 degrees to any natural light source, or in a way that optimizes readability. In addition, the worktop should have a clear surface, ideally not white, so to avoid any further reflections.
● Take a 15 minute break for every two hours worked (or five minutes for every 45 minutes or 20 seconds for every 20 minutes, according to the American standard) and try to look at objects placed at a distance of at least six meters: this allows your eyes to rest.
● Use a clearly legible font (at least 12-point size), preferably in a dark colour on a light background. You should avoid using the following colour combinations: red and blue; yellow and violet; yellow and green. Red, yellow, green and orange should also not be used as background colours.
● When you are focused on the screen (i.e. when you read a text), you involuntarily reduce the frequency with which you blink . This means a lowering of protection for the front surface of the eye (cornea); to avoid ocular dryness it can be useful to pay attention to NOT reducing levels of blinking, and if necessary, use artificial tears.
OCULAR DISORDERS ASSOCIATED WITH THE USE OF SCREENS
The prolonged use of screens (as well as smartphones or tablets) may result in ocular disorders such as burning, redness, lacrimation or dryness, discomfort to light exposure (photophobia), a sense of tiredness and transient visual blurring or fading (generally referred to as Computer Vision Syndrome) .
All these disorders can be controlled by reducing the time spent in front of the screen, taking more frequent breaks, or suspending their use for a period of time proportional to the severity of any disturbance (it is recommended, in this case, to temporarily avoid the use of contact lenses and use glasses fitted with anti-reflection lenses).
However it is always advisable to arrange an eye examination if the ailments persist. If you are suffering from conjunctivitis, keratitis and other ocular diseases of an inflammatory nature (especially in an acute form) it may be advisable to minimize the activity performed in front of a screen or suspend it altogether for a short period of time.
WHAT DOES THE WORLD OF RESEARCH SAY?
A scientific study published in 2013 stated that ocular fatigue is the most frequent complaint among people who work with a computer for more than six hours per day. Other ocular disturbances that are mentioned in the study are itching and a burning sensation in the eye. “We also found – write the researchers S. Agarwal, D. Goel and A. Sharma  – that maintaining ideal distance from screen, keeping level of eyes above the top of screen, taking frequent breaks, using LCD monitors and using antiglare screen and adjusting brightness levels according to workplace reduced these ocular complaints to a significant level”.
Another study has underlined, among other things, how the use of screens before going to sleep can induce insomnia because it can alter circadian cycles (in particular mobile-phone screens and e-book readers). This effect could be caused, not only by excessive brightness, but also by the frequency of blue light.
Meanwhile, with regards to children and the intensive use of mobile screens, a Korean university study published on BMC Ophthalmology (conducted on 916 very young children) has concluded:
Smartphone use in children was strongly associated with pediatric DED [Dry Eye Syndrome]; however, outdoor activity appeared to be protective against pediatric DED. Older-grade students in urban environments had DED risk factors (long duration of smartphone use), and a short duration of outdoor activity time. Therefore, close observation and caution are needed when older children in urban areas use smartphones. 
Please note: the use of screens is NOT ASSOCIATED to the occurrence of ocular diseases such as GLAUCOMA, DIABETIC RETINOPATHY, HYPERTENSIVE RETINOPATHY or even to the alteration of the OPTICAL NERVE, and is not the cause of any eventual aggravation.
Useful link: WHO
 The Article no. 174 of the aforementioned Legislative Decree no. 81/2008 ("Obligations of the employer") reads: 1. The employer, when assessing the risk, [...] analyzes the jobs with particular regard to : a) the risks to sight and eyes; b) problems related to posture and physical or mental fatigue; c) under ergonomic conditions and environmental hygiene. 2. The employer shall take appropriate measures to remedy the risks encountered [...], taking into account the sum or combination of the impact of the risks found.
As a scientific study, read also the following: Journal of Clinical and Diagnostic Research, 2013 February, Vol-7 (2), pp. 331-335
 Porcar E, Pons AM, Lorente A, "Visual and ocular effects from the use of flat-panel displays", Int.J. Ophthalmol., Jun 18, 2016; 9 (6): 881-5. doi: 10.18240 / ijo.2016.06.16, eCollection 2016: out of 116 people who used the computer, 72% reported related visual ailments and, in particular, medium-to-severe eye strain (14%), susceptibility to intense light (12 %), blurred vision from afar in spite of possible correction (10%), visual fatigue, dry eye, irritated eyes or burning eyes (9%), difficulty in focusing from one distance to another or headache (8%), blurred vision at close range or medium distance (<4%). Visual symptoms are slightly greater in women and worse with video abuse, especially over six hours of use on the same day
 "Evaluation of the Factors which Contribute to the Ocular Complaints in Computer Users", J Clin Diagn Res. 2013 Feb;7(2):331-5. doi: 10.7860/JCDR/2013/5150.2760. Epub 2012 Dec 24
 Moon JH, Kim KW, Moon NJ, "Smartphone use is a risk factor for a pediatric dry eye disease: a case control study", BMC Ophthalmol., 2016 Oct 28; 16 (1): 188
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Published on 25 October 2018. Updated on: 25 October 2018.
Last scientific review: 18 settembre 2017.