Short sightedness, or myopia, is a common vision condition where distant objects appear blurry while close-up objects remain clear. It happens when the eyeball grows slightly too long from front to back, causing light to focus in front of the retina instead of directly on it. Nearly half the world’s population is projected to have some degree of myopia by 2050, making it one of the most widespread eye conditions on the planet.
How the Eye Creates Blurry Distance Vision
Your eye works like a camera. Light enters through the cornea and lens, which bend it to focus on the retina at the back of the eye. In a normally shaped eye, the image lands precisely on the retina, producing a sharp picture. In a short sighted eye, the eyeball is too long (or less commonly, the cornea curves too steeply), so the image falls short of the retina. The result: anything far away looks fuzzy, while nearby objects, which naturally focus further back, still appear sharp.
The main physical measurement behind myopia is axial length, the total distance from the front of the eye to the retina. It combines the depth of the front chamber, the thickness of the lens, and the depth of the space behind the lens. Even a millimeter or two of extra length is enough to shift your focal point and blur your distance vision noticeably.
Recognizing the Symptoms
The hallmark sign is difficulty seeing things far away. Road signs, whiteboards, TV screens across the room, and faces at a distance all look soft or unclear. Up close, everything is fine. Other common symptoms include frequent squinting, headaches, eye strain, and feeling unusually tired during activities that require distance vision like driving or watching sports.
In children, the signs can be subtler. A child who holds books very close to their face, loses focus in class, or has unexplained drops in school performance may be struggling with undiagnosed myopia. Because kids often assume everyone sees the way they do, they rarely complain about blurry vision on their own.
What Causes It
Genetics
Family history plays a significant role. If one parent is short sighted, a child has roughly a 1 in 3 chance of developing myopia. If both parents are short sighted, that rises to about 1 in 2. Looked at another way, having one myopic parent triples a child’s risk, and two myopic parents increase it nearly sixfold. Genetics don’t guarantee the condition, but they set the stage.
Time Outdoors and Near Work
Environment is the other major driver, and it increasingly looks like the bigger one for explaining the global surge in myopia. Children with low sunlight exposure and high amounts of close-up work (reading, screens, handheld devices) are about 2.6 times more likely to develop myopia than peers who spend more time outside. One leading theory is that natural sunlight triggers the release of a chemical signal in the retina that slows the elongation of the eyeball, the very process that causes myopia.
The COVID-19 lockdowns offered a dramatic, real-world illustration. When children’s average daily screen time jumped from about 2 hours to nearly 6, and outdoor activity plummeted (from 78% of children regularly playing outside down to just 18%), researchers saw a significant worsening of myopia in those groups over two years. After restrictions lifted and screen time dropped back toward normal while outdoor play resumed, the progression of myopia slowed considerably. Studies consistently associate more than 2 hours of daily screen time with faster myopic shifts in children.
Mild, Moderate, and High Myopia
Eye prescriptions for short sightedness are measured in diopters, written as a negative number. The higher the number, the stronger the correction needed.
- Mild (low) myopia: less than -3.00 diopters. Distance vision is blurry but manageable in some situations without glasses.
- Moderate myopia: -3.00 to -6.00 diopters. Clear vision without correction is limited to arm’s length or closer.
- High (severe) myopia: greater than -6.00 diopters. Without correction, only objects very close to the face are in focus.
An estimated 938 million people worldwide will have high myopia by 2050, roughly 10% of the global population. That matters because higher levels of myopia carry health risks beyond just needing thicker lenses.
Long-Term Risks of High Myopia
A stretched eyeball doesn’t just blur your vision. It physically thins the retina and other internal structures, raising the odds of several serious eye conditions later in life. The risks climb steeply with the degree of myopia:
- Retinal detachment: 3 times more likely at -2.00 diopters, 9 times more likely at -6.00, and 22 times more likely at -8.00.
- Myopic maculopathy (damage to the central retina): 2 times more likely at -2.00, but a striking 127 times more likely at -8.00.
- Glaucoma: roughly 2 to 3 times more likely once myopia reaches moderate to high levels.
- Cataracts: 2 to 6 times more likely depending on severity.
This is why eye care professionals increasingly focus not just on correcting myopia but on slowing its progression in children, when the eyeball is still growing.
How Short Sightedness Is Corrected
The simplest and most common correction is a concave (curved inward) lens, whether in glasses or contact lenses. These lenses spread light rays slightly before they enter the eye, pushing the focal point back onto the retina where it belongs. You get an updated prescription as your eyes change, and for most people this is all the treatment they ever need.
For adults who want to reduce or eliminate their dependence on glasses, laser vision correction reshapes the cornea to change how it bends light. The most well-known procedures are LASIK, PRK, and SMILE, each using a laser to make precise adjustments to the corneal surface. Another surgical option involves placing an artificial lens inside the eye, either alongside or in place of the natural lens. These procedures are typically for adults whose prescriptions have been stable for at least a year or two.
Slowing Progression in Children
Because myopia usually develops and worsens during childhood and adolescence (while the eye is still growing), there’s a window of opportunity to slow it down. Several approaches have shown real results.
Orthokeratology, often called ortho-k, uses custom-fitted rigid contact lenses worn overnight. They gently reshape the cornea while a child sleeps, providing clear vision the next day without glasses or daytime contacts. Studies show ortho-k can reduce myopia progression by roughly 50 to 60%. The effect is temporary: if the child stops wearing the lenses at night, the cornea returns to its original shape and myopia comes back.
Low-dose atropine eye drops are another option, typically prescribed for children aged 5 and older. These drops are used daily and need to be continued for years to maintain the slowing effect. The evidence has been mixed on the ideal concentration. Very low doses have shown modest benefit, though regulatory approval varies by country. If the drops are stopped, myopia progression can resume.
The most accessible intervention is simply more time outdoors. Encouraging children to spend meaningful time in natural daylight, ideally at least 1 to 2 hours per day, and limiting prolonged close-up screen use to under 2 hours where possible, addresses two of the strongest environmental risk factors at once.