Digital Eye Strain – time to take another look at the lights?
You’re probably sitting on an adjustable office chair, perhaps at a sit-stand desk – and almost certainly using a mouse and pad engineered to reduce risk of repetitive strain injury and painful chronic conditions like carpel tunnel syndrome.
But what about the lights?
The rules about visual ergonomics for people who use screens – which is most of us for most of the time – are enshrined in the HSE Provision and Use of Work Equipment Regulations 1998 (PUWER).
Although written over 25 years ago for heavy machinery, the basic principles still apply: a business needs to make sure anyone carrying out duties on their behalf is given the tools they need to do so effectively and safely. The SLL Lighting Code updated in 2022 offers clear and wide-ranging guidance on ambient lighting and controls, but does not tackle the complexities of computer displays.
But, given that a recent study of over 400 employees in the UK and Ireland found that over 60% of respondents reported Digital Eye Strain, with 8% considering symptoms severe enough to affect their work – and over 90% reporting musculoskeletal issues linked to screen use – perhaps it’s worth a quick look at what the science says about safe use of screens – Digital eye strain and its impact on working adults in the UK and Ireland.
The quality of monitor is the obvious starting point – refresh rates of 144 Hz and above reduces risk of headaches and eye strain as the brain responds to flicker at speeds much higher than you can actually ‘see’ – Effect of multi-refresh-rate method on user experience: sustained attention and inattentional blindness. Size and curvature also count – above 33 inches, introducing a curve improves visual performance and reduces fatigue – Curved Versus Flat Monitors: Interactive Effects of Display Curvature Radius and Display Size on Visual Search Performance and Visual Fatigue. A single larger screen is likely to be more comfortable than two smaller ones, although you need to be a bit further away, which can be a problem on a standard 80-cm desk – Size matters ̶ effect of screen setup on muscle activity and posture in computer work.
But you don’t have to invest in new kit – just using what we know about how your eyes work to make simple changes to your set-up is a great place to start.
- Height – aim to have your eyes at the level of the top of the screen – keeps your neck and back in a comfortable neutral position – Effects of laptop screen height on neck and shoulder muscle fatigue and spine loading for office workers, and improves blink efficiency, keeping your eyes moist and comfortable over time – The Relationship Between Dry Eye Disease and Digital Screen Use. Since researching this article, I’ve started using a pile of books to lift up my laptop and found it really helps – now waiting for the portable laptop stand and keyboard to arrive.
- Brightness – make sure the screen is slightly brighter than the ambient lighting – a clear glow, not a glare, especially in the evening when your eyes are likely to be tired already. This study is one of a growing number out there that confirms a general rule of ambient: screen ratio at 13.08–62.16 lx and 20.63–75.15 cd/m respectively – Investigation of the Optimum Display Luminance of an LCD Screen under Different Ambient Illuminances in the Evening. My laptop has an ‘automatic brightness’ function but it’s also trying to optimise battery use – I often find I need to turn it up during the day – see if you do too.
- Glare – make sure your screen and line of sight is clear of bright spots, edges and veiling glare from overhead lights, windows, slatted blinds or shiny surfaces around you. Track down the source of distraction – use a piece of card to block light from above, behind or to the side and then work out the simplest way to fix the problem – change the angle of your screen, add a net curtain to a window or move a mirror or picture frame – a couple of inches may be enough. Making sure your glasses are clean and add an anti-glare coating next time you change your prescription – I’ve found that helps a lot.
Please join me for a closer look at the science of visual ergonomics, current guidelines and standards and more practical tips in a free webinar for the Association of Chartered Physiotherapists in Occupational Health and Ergonomics. We’ll be live on the 29th of October from 11am to 12 noon.
DM me for a link to register.
ACE Lighting Update
A new publication for the lighting industry in India launches this week and it’s a privilege to be part of this cosmopolitan first edition alongside Carla Wilkins of the IALD from New York, Dean Skira of Skira Architectural Lighting based in Croatia and our own Paul Nulty. I’m making the base for lighting as a system, not a product, with examples from recent work with WCS Care and St Monica Trust. The link is here. Looking forward to reading the next one!