The human eye is incredibly sensitive. Obviously; it would have to be for us to see as well as we're able to. But whilst its sensitivity provides us with the many advantages that accompany being able to see, it also comes with a few downsides, one being its relative fragility.
Eye strain occurs as a result of this fragility and it is becoming far more prevalent than it ever has been due to modern day technology. Think about the technology that the average person is likely to use on a day-to-day basis. Better still, think about how much time you spend looking at computer monitors, TV screens, smart phones, iPads and the like.
Research has shown that over a quarter of adults in the UK will spend their days working opposite a computer screen, and when they get home they will spend their evenings in a – most likely – dimly lit room watching TV; all the while filling the time they spend travelling from home to work and vice versa looking at their phones or tablets.
Without going into too much detail, the human eye works by allowing light to enter in through the pupil. The light it takes in however does not come out of nowhere; it is projected onto an object from a light source, like the sun or a light bulb, bounces off that object and into the eye.
To prevent our eyes from taking in too much light, which would start off with being uncomfortable, then painful and eventually result in blindness, a muscle in the eye called the ciliary muscle, widens and narrows the pupil accordingly; letting in only as much light as is necessary for your eye to function.
This muscle is always active, and will open and close the pupil tens of thousands of times a day. However due to back-lit screens, high colour contrasts, and the like, this muscle has to work harder, as the pupil will narrow when you're looking at the screen, but will widen when you look away. Take into consideration that when you're looking at a screen you will blink up to 3 times less than usual, and it is unsurprising that the ciliary muscle gets overworked to the point of becoming fatigued.
Eye strain is a form of repetitive strain injury, and like all RSIs when the symptoms initially occur it can be warded away by simply taking a good break from the activity causing the strain. This can be difficult if you need to work with computers, but you can always limit the amount of screen time you have after work, and lessening the brightness and contrast will work wonders.
For more information on other types of RSI, take a look at our Ultimate Guide To Repetitive Strain Injuries, which contains details on what causes a RSI, why repetitive strain injuries occur, preventing RSIs, how to treat them, and much more.