Vision is Changing Around the World
The most common conditions that cause vision to be out of focus are myopia (nearsightedness), hyperopia (farsightedness), astigmatism (distortion), and presbyopia (condition affecting small print). Research in the United States, the Vision In Preschoolers Study, attempted to identify the percentage of children who had difficulty seeing. The results varied slightly, based on location, but overall, the results were in the 25 to 30% range; less than 1% had a health condition affecting their eyes. That means that out of 100 kindergarten age children, about 25 to 30 had some type of problem seeing clearly.
More recently, researchers have been reporting that myopia alone has increased among 12-54 year olds to 42% in the USA and to as high as 62% in some countries; other studies have reported rates above 80% in some parts of Asia. This change is alarming, but what is causing it? What societal change has occurred that would affect all of humanity around the world?
Why Vision May Be Changing
For most of history, humans lived in rural areas, but the world has become more urbanized and now almost 50% of all children are growing up in dense urban areas. Children who live in urban areas tend to live in small homes and have less access to open, outdoor areas. This environment leads to a greater use of near vision and lacks distance vision activities. Urbanization alone means greater use of near vision, but another change is adding to the problem and may be in your hand right now - an electronic device.
Where are you holding your smart phone? Probably too near and with your neck bent. Is the lighting adequate? Probably not. Is the font small? Probably yes. These conditions are not ideal for reading and can produce eye and neck strain, but an adult's eyes have already developed, but not the eyes of a child. Human eyes are designed for looking out at the world, not into the world of an electronic device. Their lack of distance vision stimulation, demand for near vision, and excessive use seems to be another factor accelerating the increase in myopia .
While both environment and electronic devices are important, myopia in children is more likely if a parent is myopic. If both parents are myopic, the odds increase even further. Not only do children share their parents' genes, but they also share the same environment. Parents who live in an urban area will have children who are raised in that same urban area and if the parents use electronic devices, so will their children. Thus we are living in a time when more children are becoming myopic, who then pass that trait onto their children, and who live in an environment that promotes further progression of myopia.
Why is there concern about increasing myopia when eye glasses, contact lenses or LASIK can help people to see better? Myopia is more than having blurry vision. A myopic eye is slightly longer than a normal eye which stretches the internal structures and can lead to eye health problems such as cataracts, glaucoma, retinal detachment, and even a 9 times greater risk for macular degeneration (for comparision, smoking increases the risk by 6 times). Not everyone who has myopia develops these diseases, but the rates are higher than for people who do not have myopia; the rates are highest for those with high myopia. These potential changes in the next generation's eye health are concerning and is why myopia's dramatic increase has become so important, especially with 1 in 10 persons predicted to develop high myopia.
Myopia Control
Researchers have found that it is possible to slow the progression of myopia; the goal is to decrease the rate of change by at least 50%. If a myopic child could be kept from progressing from a -1.00 prescription to a -3.00, their risk of cataracts would decrease by 1.5 times, retinal detachment by 3 times, and macular degeneration by 4 to 5 times. Techniques currently available that attain this goal, which may be used in combination, include 0.05% Atropine eye drops, multifocal soft contact lenses (worn during the day), and orthokeratology contact lenses (worn during the night). All have shown an effect in slowing myopia progression, but progression cannot be totally stopped because children will continue to grow.
Some parents may believe that not wearing a prescription somehow "strengthens" the eyes, but not wearing, or having outdated, contact lenses or eyeglasses will cause myopia to increase faster. Children who are changing rapidly need their prescriptions to be updated more often than annually so that the full prescription is being provided at all times.
Myopia Control at Home
Changing the environment at home can further affect the progression of myopia in children. Today, the typical child arrives to a home surrounded by electronic devices after having already spent hours using them at school. Limiting use at home may sound like a solution, but that is not enough. The eyes need distance vision stimulation for normal development with the current estimate being at least 10 hours per week or about 90 minutes per day. Playing outside is the obvious choice, but what about when the weather does not allow it? Any time spent stimulating distance vision is beneficial and that includes taking children out of the home to run errands. Stores have larger inside spaces than a home, but if an electronic device is used once there, or getting there, then the opportunity to stimulate distance vision has been lost.
Should parents consider prohibiting all electronic device use? That does not seem reasonable, but putting limits on use does make sense. Current estimates are that a break from an electronic device is needed every 30 minutes. This does not mean turning away from a cell phone to use a tablet, but breaking away completely from electronic devices for at least 5 minutes before continuing.
