How often do you think you blink? And how often do you think you blink when using a computer?
Most of us blink about 15 times per minute, or once every 4 seconds. A blink lasts about 1/10 of a second. When staring at a computer screen, our blinks per minute decrease by as much as 60-80%, to 3-4 blinks per minute! We basically blink less when looking at something bright.
In addition to this, a study found that looking downward at a 45 degree angle exposes up to 40% less of the eyeball's surface than when looking straight ahead. That's less eyeball for tears to evaporate from, which they do more rapidly when staring at monitor screens . One of the most important functions of blinking is to lubricate the eyeball . Without this lubrication we can develop uncomfortable eye dryness. It gets worse for users of contact lenses and in air conditioned offices.
Eye fatigue occurs when we've been trying to focus for too long on objects close to our faces. The most comfortable focus point is at least 75cm from our eyes, and this distance will increase with age. Screens should be at least arms length from our faces, even then the longer we stare at that distance, the more we fatigue both intraocular (lens adjusting) muscles and extraocular (eyeball moving) muscles. Rubbing your eyes? We're not surprised!
And if you're wondering how this relates to the physiotherapy side of computer problems, it is essentially a constant compromise between ideal visual set up and ideal postural set up. We want to get both of them as comfortable as possible to minimise neck pain.
Try Doing These Things
The most obvious solution to reducing or preventing dry eyes and eye fatigue, is to spend less time staring at a computer screen. For some people in their work it may be impractical to get up and do something else, but for most of us, the filing drawer beckons, as does the printer, the bathroom, the water cooler and the lunchroom. Got a question for your boss? Go over and ask them, and if it needs to be in writing, follow your trip up with an email. Hand write the things that don't absolutely need to be typed. Here are some specific tips and exercises:
Every time you complete a task, take your eyes away from the screen. Close them for 5 seconds and even squeeze the lids a little to increase lubrication. Now look at an object at least 20 feet away (6m), for 20 seconds.
Turn this into the 20/20/20 Rule by doing it every 20 minutes, not just at the end of a task.
When adjusting your monitor to the correct height (top is level with the eye-ear line, try to also tilt it backward slightly, so the top is further from you than the bottom. This can have benefits for both the visual and postural systems of the body, however you'll lose those benefits if by tilting the screen it then reflects ceiling lights! Use your best judgement there.
Much of the management here lies in workstation set up, so make sure you check out the Ideal Workstation blog for the all important tips!