High myopia is a condition classified by a very high level of nearsightedness. Since myopia is the medical name for nearsightedness, “high myopia” is another way of saying “severe nearsightedness.”
If left untreated, high myopia can exponentially increase your risk of developing sight-threatening eye disease later in life.
Most people who go on to develop high myopia become nearsighted during early childhood. Their nearsightedness then progresses and worsens over time, roughly between grade-school age and young adulthood (ages 18-20). In some cases, nearsightedness will continue to progress past age 20.
After myopia has completely progressed, it will stabilize.
High myopia is a growing concern around the world. In 2015, the World Health Organization estimated that 2.8% of the global population had high myopia. They believe that number will nearly quadruple over the next few decades, rising to 10% of the world’s population by 2050.
Refractive errors like nearsightedness and farsightedness are measured in units called diopters. The term “high myopia” is generally used to describe a refractive measurement of -6.00 diopters or higher. For reference, mild nearsightedness usually falls between -0.25 and -3.00 diopters.
Nearsightedness usually occurs as the result of a slightly elongated eyeball shape. When the eyeball is too long, light focuses too far in front of the retina, a thin membrane that “receives” all light from the outside world. This causes close objects to look clear, while distant objects look blurry.
People with high myopia have a longer eyeball shape than people with mild myopia. This means light focuses even farther away from their retinas and makes distance vision extremely blurry.
Inherited genes can play a role in the development of high myopia. Children have a greater risk of developing the condition when one or both parents has severe nearsightedness.
Severe myopia does not generally lead to vision loss on its own. Instead, people with the condition have a greater risk of developing separate vision-threatening ailments, including:
For this reason, it’s essential that people with high myopia have routine eye exams, so their eye doctor can monitor the health of their eyes and look for signs of these and other complications of severe nearsightedness.
One study that examined the rates of high myopia risks made the following conclusions:
Those with high myopia are 5 to 6 times more likely to suffer from a retinal detachment than those with a low degree of myopia.
People with moderate to high myopia had nearly 50% higher risk of developing open-angle glaucoma.
High myopes are 17% more likely to need cataract removal surgery than those with a moderate amount of myopia.
The risk of developing myopic macular degeneration “rises sharply with age and increasing myopia.”
If your child's nearsightedness is worsening year after year, ask your eye doctor about myopia control methods to slow or halt the progression of nearsightedness.
One option is orthokeratology, which involves fitting specially designed contact lenses that are worn nightly during sleep. The lenses gently reshape the cornea of the eye overnight, resulting in clear vision without corrective lenses during the day.
Though the vision correction effect of ortho-k is temporary (the lenses must be worn nightly to keep daytime vision clear), this process has been shown to slow the progression of myopia.
For more information about nearsightedness and how to prevent high myopia in your child, schedule an eye exam with an eye doctor.
READ MORE: Myopia causes: Is your child at risk?
Page updated January 2021