DW: What’s the reason more and more people round the world are going nearsighted?
Dr. Frank Schaeffel: Nearsightedness is indeed a question of education. That’s one result all the studies that have been done so far have in common. Nearsightedness is related to frequent periods spent in light that’s too low, such as is often found in offices and closed spaces, while the time spent out in the open during daylight hours is drastically reduced. Nearsightedness also occurs when our eyes constantly have to focus up close. If we read a lot, we’ll eventually become nearsighted, even if our parents weren’t. The bottom line is that nearsightedness is a consequence of today’s lifestyle. The importance of education has been growing since the war, and greater weight has been given to training, so nearsightedness has also been steadily increasing. My assumptions are supported by the fact that high rates of myopia were observed once before in Germany in 1860.
Why is the rate of nearsightedness in young people particularly high in Asia?
Education has become particularly intense in Asia. From their third year on, the children have to spend almost the entire day inside learning to read. The competition over there is quite a bit stronger. Plus, the children hardly ever go outside. I’ve just received some more data from Singapore, where, even before they start school, the children spend at most around twenty minutes in daylight. This is the reason they’re exposed to less and less illumination. Much is being done to change that. These are the two main problems at the root of why nearsightedness has become so widespread there.
We’re constantly seeing young people focused only on their smartphones. How does that affect their eyes in the long term?
That smartphones promote nearsightedness cannot really be proven. It’s certain that they mean more ‘near-work’, but the user looks farther away more frequently, at bus stops, for example. But a computer monitor can’t be expected to have a different effect from a book – although we always have to be prepared for surprises. I was just at the 15th International Myopia Conference in China, which dealt with nearsightedness. There I heard a description of how blue light causes nearsightedness in two species of ape, even though just the opposite had been expected. For this reason, we should be cautious as long as we have no data about the effects of the light from displays on nearsightedness.
What do we know about the development of nearsightedness?
Much is now known about what constitutes myopia, but not everything has been scientifically proven. It’s not as if a given gene is switched on or off, and you turn nearsighted, or you don’t, as was previously thought. Myopia is of a similar complexity as cancer, Alzheimer’s and Parkinson’s or any other of these complex and widespread diseases, because the interactions between genetic and environmental factors are crucial. Now about forty genes have been identified that can predict myopia, but many others are as yet unknown. And in the end, this knowledge doesn’t save people from myopia. The greater share of myopia these days is not hereditary, but a factor of an environment that’s primarily determined by external lighting.
Can nearsightedness be prevented?
Yes. It’s been found that, if children spend enough time in the open air before they start school, the prevalence of myopia in later years can be noticeably minimized. Taiwan has made the most progress here. A directive issued by the education ministry in 2012 that prescribes at least 120 minutes of outdoor activity has had clearly positive results among first-graders. Some kids in Singapore wear a kind of watch that indicates how bright the light is and how much time they’ve already spent outside. What else can be done – and is obligatory in Taiwan – is spending at least ten minutes looking into the distance for every thirty minutes of ‘near-work’.
Are there new therapies for nearsightedness on the horizon?
At present, efforts are focused on slowing the progress of myopia during the school years as much as possible. In addition, now we have a new kind of lens for glasses. Nearsightedness can be inhibited with these new lenses. On average, you can say that these new lenses can achieve about thirty to forty percent inhibiting of nearsightedness. Another possibility for inhibiting the progress of nearsightedness right now is administering very low concentrations of atropine (0.01%), an agent from belladonna that slows the advance of nearsightedness in children with the appearance of very few side effects.
Many people believe that glasses only worsen vision, and they try to get by as long as possible without. Is this preconception justified?
There was a time when I would have subscribed to that view, as well. If you put lenses on an animal, it will become far-sighted. So it’s a vision correction that makes the eye go nearsighted. But on people, it doesn’t work. In general you can say, whether you wear glasses or not hardly makes any difference in the progress of nearsightedness. The same goes for under-correcting, which is supposed to bring the progress of a vision problem to a halt by using lenses that are a bit too weak. Based on animal experiments, I would have also subscribed to that view, but the data from children are less than convincing. In studies where subjects wore lenses under-corrected by three quarters of one diopter, sometimes, the myopia progressed even faster than it did in the control group wearing lenses that fully corrected for it. That indicates that not correcting for nearsightedness does not result in any improvement. But more research needs to be done here.
We keep seeing reports that special exercises for the eye muscles can improve our vision. Is that right?
I would definitely NOT subscribe to the idea that it can eliminate nearsightedness. But what you CAN exercise is your ability to see more in spite of a worsening image. There are training programs on the computer. That comes from the fact that our vision system can heighten its sensitivity when information is scant. But that’s not an improvement to vision per se. The eye does not become less nearsighted – the brain learns to get along better with less information.
Professor Frank Schaeffel is director of the Tübingen University Eye Hospital, Section for the Neurobiology of the Eye. He researches the causes of nearsightedness.
Interview: Marita Brinkmann