Many individuals have probably heard of myopia—the leading cause for needing prescription glasses in those under 45 years old—but many likely have not heard of just how serious the rate of progression of myopia is worldwide.
Myopia is the medical term used to describe those who are nearsighted (can see well up close but things far away are blurry).
In a 2019 study, it was found that over 32% of the world has myopia. That’s over 2,528,000,000 individuals affected, with this number increasing at a faster rate than ever before.
To put this into perspective, according to WHO as of December 13, 2021, 3.9% of the global population, or 271,963,258 individuals, have contracted COVID since its arrival in early 2020 (i.e. confirmed cases).
Of course, COVID and myopia are nothing alike. These are just statistics to help emphasize how prevalent myopia is.
But what exactly is myopia, why are so many people affected by it, and why should we care?
To understand myopia, it is best to have a basic understanding of how vision works.
To form vision, light must pass through the eye to reach the back most structure of the eye called the retina.
The retina contains millions of specialized cells called photoreceptors that become stimulated in the presence of light. Once stimulated, photoreceptors send signals to the brain where the accumulation of signals are processed to form an image.
What is especially important to note is that for an image to be created clearly and in focus, the light reaching the retina must come to a point to stimulate just a handful of photoreceptors.
If the incoming light rays come to a point in front of or behind the retina, a blur circle is created instead of a sharp, clear image.
Objects (a tree, chair, lamp, whatever you are looking at) omit parallel light. This means light rays must be bent by the eye to create the point source on the retina.
If light is bent too much, the focus point lands in front of the retina—thus creating blur on the retina and the image appears fuzzy.
If light is bent too little, the focus point lands behind the retina—again creating a blurry image.
Myopia, or near-sightedness, is the term used to describe a condition in which light is bent too much, creating a point source in front of the retina, and thus blurry vision.
Myopia can be caused through two different processes—either the eye’s power is too strong (causing it to bend light too much) or the eye is too large (again causing light to be bent too much).
“Too large” of eyes means the length of the eye from front to back is longer than normal. The average length of the adult human eye is 24 millimeters. A deviation as small as 0.25 millimeter too long can induce myopia!
With any medical condition, it is important to understand the “what” and “how”. What is the condition and how does it occur?
We now know what myopia is (the what). But what about the how? What causes myopia?
Myopia has some genetic component. If one parent is myopic, his/her child has a 20-25% risk of developing myopia. If both parents are myopic, their child has a 30%-40% risk of developing myopia.
As stated above, with almost 1/3rd of the world’s population being myopic, there is a good chance that at least one parent will be myopic in set of biological parents. As the number of individuals with myopia increases worldwide, this probability will only continue to grow.
There is also a large developmental component to myopia development.
The eye continues to mature and grow until the age of 18, with the greatest period of susceptibility being between the age of birth to 7 years of age.
Development on the eyes is dependent on blur. Blur causes the eye to grow more, and remember, too large of eyes is one of the causes of myopia!
Another important note to make is that near work (reading, cellphone use, computer use, watching TV, etc.) requires light to be bent more, as the distance between the object and the eye is reduced, meaning more light must be bent in a shorter distance.
Unfortunately, as technology becomes more and more popular, our near demand is ever increasing.
Now a days, it is not uncommon for a teenager, child, or even toddler to spend hours reading, writing, doing computer work, watching TV, and/or playing on an iPad or other tablet each day.
What do you think this does to eye development? It shifts the emphasis of development from clear, well-focused distance vision to clear, well-focused near vision. Therefore, during the critical years of development, the emphasis for clear near vision causes the eye to elongate—creating myopia.
With there already being a high genetic disposition to myopia, a developmental emphasis to stimulate eye growth, further expanding myopia, only contributes to the myopia epidemic on an exponential level.
While the entire blame cannot be put on an emphasis of near work—the exact mechanism of myopia development is still unknown at this time—there is evidence of a very strong connection between the two.
It is quite possible that today’s current societal focus of near work and obsession with computers, cell phones, and tablets, is shifting human evolution toward more myopic eyes.
In fact, several studies have shown that increasing time outdoors, where the primary visual focus is at a distance greater than 6 meters, reduces myopia development in children in comparison to children who primarily played indoors or spent the majority of their free time on electronics.
While near work seems to be inevitable in today’s world, it is more important than ever to continue to encourage children to play outside for at least 1-2 hours a day when possible, and to take breaks during near tasks to focus on an object in the distance to keep the eyes’ primary focus on distance objects.
Is clear near vision and wearing glasses really the end of the world—probably not. However, there are many health risks associated with myopic eyes that are much more worrisome than needing to wear a pair of glasses.
At this point, we know myopia corresponds with an increased length of the eyes. When the eye is too large, it stretches out the retina leading to an increased risk of retinal tears, retinal detachment, glaucoma development, macular degeneration, cataract growth, permanent blindness, and more.
Myopia is categorized into three major categories for risk assessment—mild, moderate, and high.
Mild myopia is myopia of -0.25 to -2.75 diopters. Individuals who fall in this range have 3x the average risk for retinal detachment, 4x the risk for developing glaucoma, 2x the risk for developing macular degeneration, and 2x the risk for developing early onset or more severe cataracts.
Moderate myopia is myopia of -3.00 to -5.75 diopters. Individuals who fall in this range have 9x the average risk for retinal detachment, 4x the risk for developing glaucoma, 10x the risk for developing macular degeneration, and 3x the risk for developing early onset or more severe cataracts.
High myopia is myopia of -6.00 or higher. Individuals who fall in this range have 22x the average risk for retinal detachment, 14x the risk for developing glaucoma, 41x the risk of developing macular degeneration, and 5x the risk of developing early onset or more severe cataracts.
Unfortunately, when it comes to things like retinal detachment, glaucoma, and macular degeneration there are no truly great treatments.
The prognosis post-retinal detachment vision changes vary, depending on the location of where the retina detaches and how quickly the retinal detachment is caught, and treatment initiated. Sometimes vision is only minorly affected. Other times, permanent blindness ensues.
In glaucoma and macular degeneration—prevention is the key treatment. Once damage to the retina occurs, it cannot be restored and thus vision will permanently be affected.
Cataracts, fortunately, can be removed via cataract surgery and vision is typically restored without incident. Cataract surgery is a surgery however, and therefore has associated risks.
While vision can typically be corrected via glasses, contact lenses, or refractive surgeries like LASIK, PRK or SMILE, the risk for these events do not go away and will remain based on pre-surgical values.
The myopia epidemic is quite scary. Researchers are working harder than ever to understand why myopia is becoming so prevalent worldwide as well as working on treatments to try and slow the development.
While completely eliminating myopia is not something that is feasible at this time, slowing down the progression of myopia is possible through myopia control.
Myopia control is treatment implemented during adolescent years (up to 18 years old) to try and slow the progression of myopia.
Myopia control is beneficial because it can take a child who, if left untreated would have a prescription of -6.50 (high myopia), and stabilize the eye growth at a prescription of -2.00 (mild myopia), thus reducing some of the risks associated with progressing to high myopia.
Myopia control is accomplished using various techniques such as using specialized contact lenses (Coopervision’s MiSight lenses, ortho-k technology, etc.), specialized glasses therapy, or even pharmacological treatment through atropine therapy.
To find the right therapy for a child, a thorough eye exam with special measurements is needed. The doctor will then decide on a treatment plan customized to the individual.
While myopia control is not successful in everyone, it is showing to be quite promising, and will hopefully be a major part of the solution to the myopia epidemic.
If you or someone you know has myopia, it is of utmost importance to have at least yearly eye exams to monitor you eye’s health.
If myopia control is applicable to you, be sure to discuss it with your doctor as it could potentially save your eyesight.
In the meantime, be sure to spend plenty of time outdoors—and don’t forget to take breaks doing near work!