Increasing numbers of young people who use smartphones and tablets for long periods are complaining of symptoms similar to those of aging eyesight -- such as blurred near-field vision -- while some people in their 40s and over have likely misattributed problems caused by phone use to the passing years.
"The number of young people who come to my clinic complaining of suspected smartphone-induced aging eyesight is on the rise," comments Rui Hiramatsu, who heads the eye clinic at the Sainokuni Higashiomiya Medical Center in Kita Ward, Saitama.
"I've even seen people in their 30s who have become dependent on reading glasses," added Hiramatsu, an expert on the relationship between smartphones and eye health.
The number of smartphone users is on the rise, with officials from the Ministry of Internal Affairs and Communications reporting the figure at 60 percent for all age groups and more than 90 percent among those in their 20s.
An inquiry by research firm Trend Soken on 5,000 smartphone users in their 20s and 30s revealed that as many as 40 percent of respondents said they believed they suffered from smartphone-induced aging eyesight.
But what exactly does this mean?
"The symptoms are exactly the same as those of actual aging eyesight," Hiramatsu explains. "At first, it becomes difficult to see nearby objects -- and additional eye-related symptoms such as chronic fatigue and concentration problems also often appear, along with stiff shoulders and irritability."
In normal cases related to advancing age, the symptoms of aging eyesight -- which is also known as presbyopia, or farsightedness due to muscle weakness and loss of elasticity -- begin to appear gradually at around age 50.
Hiramatsu explains that these symptoms in young people are often caused by holding their smartphones too close to their face.
When one reads books or newspapers, he says, these are normally held around 30 to 40 centimeters from the eyes -- whereas one tends to unconsciously hold a smartphone only 20 to 30 centimeters away. The result, says Hiramatsu, is forced use of certain eye muscles, and thus the symptoms of aging eyesight.
Understanding the reason for this first requires an explanation of the mechanics of vision. Inside each eye is a crystalline lens that works to bring objects in and out of focus by thickening and thinning -- a process regulated by what is known as the ciliary muscle.
The lens thins when one looks into the distance, the ciliary muscle relaxing. When one looks at something nearby, however, the lens thickens as the ciliary muscle contracts.
And just as one's arms and legs weaken with age, so does the ciliary muscle decline with the advancing years. This lowers the muscle's ability to contract, which results in the difficulty focusing on nearby objects that characterizes aging eyesight.
The ciliary muscle functions in a similar way, moreover, to stiff shoulders. In other words, continuing to look at nearby objects results in the muscle stiffening and lowering the eyes' ability to regulate focus -- exactly what constitutes smartphone-induced aging eyesight.
Another major cause of the condition is the light emitted by smartphone screens.
"As long as humans have been around, they have viewed objects using the reflected light of sources such as the sun, but they had never looked directly at the source of the illumination itself," Hiramatsu points out. "When one looks at a smartphone however, they end up being forced to look directly at this light source. This is problematic because it contains blue light, which is harmful to the eyes."
Blue light penetrates deeply inside the eyes, and is responsible for causing numerous types of eye disease.
Light acts on human's sympathetic nerves, stimulating them. Humans are normally meant to be exposed to light and remain active during the daytime, and become relaxed in the dark of the night. Continuous exposure to smartphone screen light, however, results in ongoing sensory stimulation. If this becomes chronic, it becomes difficult to regulate one's autonomic nerves, potentially causing problems.
Because blue light is also found in sunlight, however -- including the light at dawn -- it is impossible for humans to avoid it entirely. The key, therefore, is to minimize exposure as much as possible. Hiramatsu says that there are three specific ways to avoid contracting smartphone-induced aging eyesight.
"The first," he notes, "is not to bring the smartphone too close to one's eyes. If possible, it should be kept at a distance of around 40 centimeters."
(For perspective, one should hold a smartphone a little further away from the face than the length of an A4 piece of paper, which is around 30 centimeters.)
Next, Hiramatsu advises, "The phone's luminance -- or brightness -- should be turned down. The lower the level of illumination, the more that damage can be avoided."
Many smartphones are set on the highest luminosity level when they are first purchased, and so the setting should be manually reduced to around 70 percent.
And thirdly, the doctor advises, "When using smartphones, be sure to take breaks. A 10 to 15 minute rest should be scheduled for every 60 to 90 minutes of smartphone time."
He especially cautions that the devices not be used for around half an hour before bed, as the light can hinder getting into deep sleep.
"Implementing these three suggestions, along with wearing glasses designed to cut out blue light, is one recommended method" for avoiding smartphone-induced aging eyesight, notes Hiramatsu.
Over the past several years, the eyeglass industry has marketed many models of blue light-cutting glasses. JINS, a major eyewear company and a leader in such specs, sells numerous affordable types starting at 3,900 yen a pair (including frames -- tax not included).
And the possibility for curing smartphone-induced aging eyesight once it has set in?
"The condition is definitely curable," Hiramatsu says without hesitation. He adds, however, "It's difficult to return the eyes to their original condition once symptoms have set in, so it is best to take action early."
Concretely, he says, "The best thing that one can do is to relax the ciliary muscle."
To do this, one method is to stare off into the distance -- and then bring one's focus back to a point near the eyes. This should be repeated 10 times in a row, while imagining the ciliary muscle being stretched.
Another recommended method is to use low-strength (plus 1 to plus 2) reading glasses, available at 100 yen stores. Looking at something out of focus while wearing the glasses even for five minutes per day, Dr. Hiramatsu says, can make a difference.
"And while smartphone-induced aging eyesight is often thought to be associated specifically with young people, it can also affect middle-aged and elderly persons," he also notes.
Sometimes, people in their 40s who believe that they have standard aging eyesight are actually suffering from the problem due to their smartphones. The two conditions can also sometimes occur simultaneously, with the normal process of aging eyesight continuing to advance unchecked. Hiramatsu's method for dealing with smartphone-induced aging eyesight is both easy and can, moreover, also delay the onset of normal aging eyesight.
Researching the condition of smartphone-induced aging eyesight makes smartphones seem slightly frightening. And yet, for many people, the devices have become an indispensable tool for both work and socializing.
"Even knives can be turned into dangerous weapons, depending on how they're used," points out Hiramatsu. "If one knows the proper way to use (smartphones), there will not be any problem."
And so it is up to each one of us to use our smartphones in a way that will allow us to preserve the health of our eyes.