The invention of computer has brought unprecedented changes in the way the world works. Additionally, the boom in smartphone and tablet industry has accomplished what their bulkier ancestors were unable to. And now, with the onset of COVID era, the pattern of working of all sectors has changed drastically to incorporate the basic principles of COVID prevention techniques, one of them being social distancing. The increased use of digital devices for purposes of education and jobs has increased the prevalence of problems related to eye health. These problems in the eyes occur mainly because of two reasons. One is drying of the tear film, and the second is muscle fatigue. In this article we will discuss about these harmful effects that long hours of digital devices use have on our eyes, and about the possible ways to prevent them.
Our eyes should always be covered in a thin layer of tear film. Dryness on the ocular surface is not good. Blinking evenly distributes tear over the surface of our eyeball. This wiper action of eyelid margin over the eyeball always keeps the eyes uniformly wet. Dry spots (breaks in tear film) start appearing on the cornea only after around 10 seconds of continuous eye-opening, due to surface tension of the tear film and evaporation. So, blinking occurs naturally around once every six seconds. Now, when the eyes and mind are concentrated on the digital display, one tends to blink less frequently. This infrequent blinking leads to appearance of dry spots in-between blinks. Such occurrences over hours causes significant irritation, foreign body sensation (sensation as if some dust or eyelash has gone into the eyes), itching, burning, watering, red eyes, blurred vision, difficulty looking at bright light, or sustaining visual work, etc. For all those who have blinked first and lost in the game of aankha judhai with friends during childhood, they know the pain.
Another effect of continuous digital display use is eye muscle fatigue. Eye muscles naturally relax when the eyes stare at something that is far away. When one tries to look at something near, eye muscles contract actively to do three things: one is to make the lens in our eyes thicker to focus the near object’s image onto our retina and avoid blurring, second is to converge both our eyes at the near object, so that both eyes look at the same object simultaneously and avoid double vision, and third is to constrict our pupil to let less light in. This is called the ‘near reflex’. It happens automatically on looking at something near, and it requires muscle effort. Now, when one uses digital devices for long hours, these muscles get tired. That translates into eye fatigue, eye strain, heaviness, and even pain in the eyeballs, eyebrow, and forehead area, headache, blurring, double vision, sensitivity to bright light, dizziness, watering, decreased vision for distance, etc.
Myopia or Near Sightedness
In children, a third effect of prolonged near vision sets in viz. near sightedness, or myopia or minus refractive error. Myopic eyes are longer/ larger than usual. The stimulus for an eyeball to grow in length is blurry vision. Long hours of computer, tablets, mobile use, books, even, causes eye muscles to get fatigued, and thus blurring of image. This stimulates the eyes to grow, and thus minus number increases. So, if one’s child is on the computer all the time, or playing mobile games all the time, or even studying continuously for hours at a stretch, we should anticipate myopia, among other things.
• There should be at least 50-70 cm distance between the digital display and eyes. Nearer placement of screen increases strain on the ciliary muscles of the eyes, and thus, fatigue. To keep working easily from a distance, the text and graphics can be enlarged to maximum possible, also a magnifier tool can be used on screen to read out texts easily.
• Similarly, in the display settings, the brightness of the screen should be adjusted so that it is the same as the surroundings, and the contrast should be increased. Higher brightness constricts the pupil and may fatigue the pupillary muscle, and thus, later increase intolerance to bright light.
• The image/text parameters should also be adjusted for resolution, size, contrast, and brightness in such a way that the ease of viewing is maximized.
• LCD screens are preferable to CRT monitors. Similarly, use of antiglare cover over the screen is recommended. Screens should be clean and free from dust or smudges. So, regular cleaning is advised.
• The positioning of the screen should be such that, while working, our eyes should look in a slight downward gaze to look at the screen. One way to ensure this is to adjust chair height and display unit height in such a way that the top border of the display is below the level of the observer’s eyes. This is to minimize the opening of our eyelids, so that less eyeball surface is exposed to air, leading to less evaporation and dryness. This also prevents pain and spasm in the neck muscles.
• 20-20-20 rule: Intermittent breaks for the eye muscles is necessary. It is recommended to take your eyes of the screen once every 20 minutes for a period of 20 seconds to look at something at least 20 feet far.
• 6 hours rule: Try to curtail total cumulative digital screen use to less than 6 hours per day. Studies have suggested significant increase in complaints in people who use digital device more than 6 hours per day.
• Blue-cut glasses: Several health benefits have been proposed and thus lenses that cut out UV and blue rays from white light can be worn during working hours to avoid the harm white displays and lighting might bring in our eyes and health.
• Lubrication: An artificial tear should be used at least four times a day to as frequently as one-hourly in people using the computer for a long time.
• In the case of children, it has been found that at least two hours of outdoor play daily has a beneficial preventive effect on myopia.
• Legislation: Policy makers should realize the potential adverse effects to ocular health by increased digital screen use, and thus put a cap on the maximum hours any child or adult is allowed to work on the computer system.
One thought of mine I keep sharing with my patients every now and then is that human beings had to live in jungle and caves few millennia back. Eyes were used to hunt and farm mostly in the open. Computers have been introduced to our lives a few decades back only. Our bodies’ functions and capacities haven’t changed much biologically since we were in caves. But, the demands from the same human body has changed drastically. For one, eyes are now used indoors for long hours to scroll endless pages, pdfs, codes, Facebook feed, or YouTube videos on computer screen or smartphone. It might take many millennia for human beings to evolve to be able to live effortlessly in these newer living conditions, if at all that is going to happen. Till then, we ought to start inculcating some preventive measures into our daily lives to be able to enjoy the bliss of healthy eyes forever.