As human history goes, we have always been animals that viewed distant vistas much more so then near objects. We farmed and hunted for survival, giving us tens of thousands of years evolving our species. It has only been over the past several hundred years that books and news print finally made its way to the public, mainly for the wealthy. During the Twentieth Century, books and newspapers finally became more mainstream and allowed the general public a new viewing demand. The mid 1950’s launched a new visual device that the public became captivated with, the television was finally affordable. The advent of TV presented a new focal consideration for our eyes and brain. From the 1960’s through the 70’s the TV evolved from black and white to color, changing our perceptual awareness that began to invade our world of information. During the 1980’s through to the 2000’s, the TV monitors shifted their viewing distances from the 10-15 foot range to the 14-24 inch distance as computer monitors. The movement of the computer monitor changed the way society worked and played. People made their livelihood utilizing back lit monitors hours at a time. As our work places became saturated with computers to help us work more proficiently, the demands on our eyes began to show it. Our work hours continued to increase with the use of computers, but we tended to return home to relax our eyes by viewing normal distances such as playing outside, watching TV or reading books. In the early 2000’s a new device became popular with societies desire for communication, the cell phone went main stream. As these devices had tiny screens with poor quality graphics, the evolution was soon to change. In 2006 the phone became a tiny computer with a screen to match. These new devices allowed people to keep up with emails and texts, giving them greater work and play communication. In 2009 the iphone phenomenon took over the world as not only the device to keep up with emails and texting, but as a new social media device. We now play games, view video’s, text, facebook, twitter take photos and overall keep up with society on our hand held mobile phones. These new devices are not only back lit like their cousins, the computer monitor, they are held at an even closer distance. Even now as we utilize these devices, here comes the new future of eye candy… the tablet computers. Tablets are now replacing not only the cell phones ability to give us our on demand connection, but are becoming our books and daily newspapers. Here too, the tablets are held at a closer distance to the eyes than computer screens. We as humans have never in our history found such great demands on our eyes than in the past five years, especially in the past two years. We must ask, what effects do these new devices have on our eyes and overall health of our body?
To best understand how these new demands will affect our eyes, we must realize the eyes mainly act as cameras for our brain. They collect light and process the desired images in the cerebral cortex of the brain. Our eyes have evolved into an incredible system for adjusting, accommodating and aligning the two images the brain receives from each eye. When the two images are processed by the brain, stereoscopic imagery appears. The brain does whatever it can to keep stereopsis, or depth perception. The easiest way for the brain to keep the visual input comfortable is to control the eyes accurately; however, our eyes are extremely complex in their control. Four of the twelve cranial nerves are involved in integrating the correct reception of each eyes respected image, correctly and precisely. Like an oxymoron, it’s simplistically complex, but the brain works it all out. When the brain struggles to keep the visual system comfortable, it lets the body know through symptoms of visual stress.
Our brain considers any distance further than twenty feet as optical infinity. At twenty feet, the accommodative system should be totally relaxed. The eye’s cilliary body or focusing muscles begin accommodating as the viewing distance becomes closer. So as hunters and gathers, we generally used our eyes at very relaxed distances. These simple demands on our eyes have been constricted over time as our reading and work environments demanded it. Our typical reading distance is determined by the Harmon rule, which is denoted as the distance from the tip of the elbow to the fist closed on the chin. This distance will vary depending on the height of the individual, thus tall people tend to hold their reading material further than shorter people. Children obviously tend to have the closest reading distance due to their size. Reading is a task that has been done for millennium, but now education is mandatory for our youth and more information is available in books, newspapers and magazines than ever before. Public consumption of printed material has notably increased over the past hundred years, but how significant has this been on our eyes. As we focus on printed material such as black print on a white background, the cilliary muscle locks its focus onto the print. As the focusing system accommodates for the near demand, like any muscle, it begins to fatigue over time. After several hours of reading, the cilliary muscle begins to fatigue and loses its ability to sustain focus accurately. This is where the blink rate comes into play. As we blink while viewing text on paper, the cilliary body relaxes when the eyes are closed. As the eye regains its focus, a quick shudder to the muscle occurs. The brain will try to help the muscle by reducing the blink rate so as not to drop focus during the blink. Our blink rates typically decline from 18-20 blinks a minute to 13-15 blinks a minute while viewing printed material. With a reduced blink rate the visual system becomes irritated by dryness, causing the eyes burn, tear and become red. If the eyes are relaxed by using corrective lenses or its own natural nearsightedness, this visual stress becomes much less of a problem. On the contrary, if the eyes are already overstressed by the patient being hyperopic or farsighted, excessive near work will exacerbate the near system. Much of this visual stress occurs with reading of text on paper, however much more accommodative strain is noted with the use back lit devices such as computer monitors or hand held devices.
Over the past thirty years our near demand has shifted dramatically, especially with the advent of the computer monitor or back lit devices. As the computer phenomenon took over our work environments during the mid 1980’s our eyes began to adjust to a new viewing distance and where our eyes could lock onto printed text, these new back lit devices cause a new dilemma. As we view a lit source, the brain cannot determine were the light actually exists in space. Thus our focusing system accommodates about an inch in front and behind the lit screen, constantly adjusting for where the brain believes the image is. As the cilliary body fluctuates its focus, the blink jumps in causing readjustment of focus. During the blink, the muscles make a quick jerk to relaxation and then pick up the refocus. There is great difficulty in a muscle doing this over 15 times a minute, so thus the blink rate drops to comfort the focusing system. The drawback to a slower blink rate is the effect of dryness such as burning, stinging, grittiness, redness and tearing. These are the classic symptoms of Computer vision syndrome (CVS) which has been a major problem with prolonged computer use over the past couple decades.
Cell phones became popular during the early 1990’s, but the true visual effects of cell phones came into play with the use of texting in the late 1990’s. The crude screens of the early cell phones were LED based, making long term use easier on the eyes as they were not back lit until color screens made their appearance. In the mid 2000’s the first smart phones became part of society’s daily activities. People could now hold their tiny computers to view most everything their home computer could show. Smart phone growth dramatically took off with the first iphone in 2007. Presently, smart phones outsell personal computers in total number. Why is all this so important? Smart phones are tiny back lit screens that are held at closer distances than the typical computer monitor. Most times, even closer than typical reading distance. Again, as we look at these miniature computer screens at 8-14 inches our focusing system becomes significantly stresses. Our blink rate drops even more dramatically and the ocular fatigue grows more quickly. While our youth have picked up on these devices to support their demand for texting, emailing, using facebook, twitter and you tube; even their youthful accommodative system becomes overwhelmed. Today, the business savvy populations of forty plus year olds are taking to the new smart phones in droves only to find their visual system over stressed leading to frontal headaches, fluctuation in vision, light sensitivity, tiredness, reduced reading ability and dry eyes. The new smart phones have brought a new social connectivness to society, and its a device we hold in our hands and usually have with us at all times. Just around the corner, we are about to be overwhelmed by the tablet computers.
Today’s tablets not only have the same capabilities of the most sophisticated smart phones, they also have a larger screen with much more functionality of a personal computer. They are lightweight and easily handled. There screen sizes range from 4-6 times larger than smart phones screens with the same resolution. The typical distance tablets are held tends to be around 10-20 inches. The wide variance in this viewing distance goes back to the Harmon distance. As more households utilize tablets, younger hands are becoming more familiar with the devices. Children are shorter and thus hold these devices closer to view. Even as a child’s accommodation is better suited to adjust at close distances, prolonged amounts of use can bring about eyestrain, especially with a back lit screen. This excessive strain can lead the visual system to a myopic shift, where the eye becomes more nearsighted to allow relaxation at near. This will eventually cause the child to need glasses for distant viewing more quickly.
Even the tallest of adults hold tablet computers closer than the average distance computer monitors sit. Pre-presbyopes can also see a shift in their need for more distance correction secondary to this excessive near strain. More adults are reading books and newspapers on tablets due to their portability and convenience. As the smart phones came with the multitude of “apps” to improve productivity and relaxation, the tablets followed with a much more comfortable screen. Most of the older generation dislikes viewing the small displays of the smart phones for long periods of time; the tablet displays allow a more comfortable size for prolonged usage. Tablet sales for 2011 are expected to be between 50-70 million devices, thus more and more adults will be utilizing these closely held devices for work and play. Again, the excessive use of these back lit devices will play a major role with the accommodative system and we should be prepared to combat their fatigue with the best possible corrective lenses.
E-readers have become popular with the reading crowd that typically goes through several books a month. The e-readers such as the Kindle and Nook use a LED based lit screen, so as to be easier on the eyes. The e-reader population is growing among the avid readers, however many more people use tablets to not only read, but to work and play on. Soon the tablet will become the leading device our children use to scholastically develop their didactic curriculum and we will have to be concerned with the visual effects that will occur.
To best help societies increased demand for these new devices, we as optometrists and opticians need to be aware of our patient’s visual requirements. Progressive lenses and anti fatigue lenses have improved dramatically over the past couple years with the advent of free form technology. Whereas the progressives of the past had small corridors for viewing, the new free form lens design dramatically opens the viewing corridor with little distortion. With the improvement of a more natural viewing environment, many patients are willing to begin wearing progressives to help relax their new increased near demands. By allowing the cilliary muscles to relax with the use of a progressive, the blink rate increases and there is less fatigue helping the patient’s concentration.
In the past, the need for a progressive lens has usually been seen to be a need at around the age of forty. This rule worked well when our patients spent 2-6 hours of their day performing near activities and most was done on a computer monitor. As the computer monitor sits out at 18-24 inches, the strain is present, but not as significant as the typical near distance of a tablet or smart phone. Prolonged amounts of near work are becoming more of the norm and these viewing distances are getting closer and closer. By best understanding our patient’s daily use of their eyes, can we truly prescribe the most optimal prescription for relaxed vision at all distances.
Regardless of age, we should have an understanding of how frequently patients work on a computer, smart phone, tablet, e-reader and with printed text. Not only is frequency an important factor, the distance these activities are being performed plays just as an essential dynamic to the equation. By knowing your patients accommodative stresses, the correct lens prescription will allow the greatest relief of the patient’s daily activities. Progressive lenses aren’t just for presbyopes anymore.
Hoya’s anti-fatigue lens, Active 8, is a great alternative for the younger patients that are becoming more involved with smart phones and tablets. This lens utilizes a front surface radial aspheric design with a back surface vertical aspheric component, allowing the benefit of .88 diopters of plus power. This nearly diopter of plus power gives the user the added relaxation to help sustain prolonged amounts of near work. Accommodative relief helps improves blink rate and overall focus on the subject. The reduction of the cilliary muscles work out may have beneficial effects in slowing the progression of myopia, especially with children that have higher myopic prescriptions. As our youth progress further with the use of tablets scholastically, Active 8 lenses will become more useful to relax this near demand. Visually, the Active 8 lenses show no peripheral distortion in comparison to progressives. By using these lenses as a first response to patients under thirty years of age who works at near more than half their day, would only be benefited by the reduced fatigue. This relaxation at near can actually bring added energy to the body in whole.
Patients who show symptoms of accommodative stress usually complain of the same things. Headaches are typically the main complaint, especially if they occur frontally and are noted after 10-15 minutes of near work. Many other symptoms may be present that can suggest eye fatigue. Increased light sensitivity occurs due to the fact that constriction of the pupil puts pressure on an already stressed cilliary body, causing the sore muscle to respond with discomfort. Fluctuation with vision, like a camera going in and out of focus, is a sure sign the accommodative system is locking up and contracting. Poor nighttime vision can also be the result of accommodative lock up secondary to a long day of near work. Reduced concentration and reading skills in general may be due to excessive difficulty focusing on the desired near work. Wanting to close the eyes at the end of day can be seen as the only way to relax the focusing system, as when the eyes are closed the muscles have nothing to focus on. The desire to rub the eyes at the end of the day is equivalent to massaging your arms after lifting all day.
Overall, the vision game has shifted from primarily viewing distant vistas to now focusing on the multitude of back lit devices. We have become an information society that works, studies, plays, shops and relaxes using these devices. Most people do not realize the amount of near viewing that goes on throughout the day. While we covered the most significant sources in the above text, we tend to ignore the little things during the day. As we shop at a supermarket or mall, we continually are alternating from the near products to the distance aisles. As we meet and greet people throughout the day, we focus on not only the conversation, but their face too. The same goes for eating, alternating from food to face. If we combined all are near experiences for a typical day, most people would be surprised at the overall time they spend looking at objects closer than an arm’s length. Thanks to the advancements of the new free form progressives and anti-fatigue lenses, our over focused society can be relieved of its strain.
