Myopia: Causes, Symptoms, Treatments
Myopia is the medical term for nearsightedness. This means you can see well for close-up tasks like reading, but distance vision is blurry. The condition occurs when the eyeball is too long, or the cornea or lens is too curved relative to the length of the eyeball.
No matter the cause, myopia causes light entering the eye to be incorrectly refracted or bent. Instead of landing on the retina, light lands just short of it. Symptoms of myopia include squinting, eye strain, and headaches.
Hyperopia and Presbyopia
In myopia’s opposite condition, hyperopia or farsightedness, light falls behind the retina. Someone who is farsighted sees well at a distance but not up close. This should not be confused with presbyopia, a condition affecting the eye’s lens in middle-aged people.
Presbyopia typically occurs in the early forties and causes focusing problems at close range, such as reading. Vision will be blurry close-up but clear in the distance. Presbyopia is caused by changes in the eye’s lens and is a normal part of aging.
What Numbers on Your Eyeglass Prescription Mean
Myopia is easily correctable with eyeglasses and contact lenses. Prescriptions for myopia will always be designated using negative numbers.
For example, the numbers referring to myopic correction will be listed in the SPHERE column on an eyeglass prescription. You may see a number like -4.00 or -4.00D. The D stands for diopter, a standard optical measurement for the necessary refraction correction.
Correction for farsightedness will be indicated by a positive number like +2.00. The CYL and AXIS columns are talking about astigmatism that needs to be corrected. If no issues are present, the space will usually be left blank.
You may also see the term plano. This is another word for 20/20 vision, although it’s possible to have 20/20 vision and still have astigmatism.
Myopia in the World Today
Worldwide, the incidence of myopia has risen sharply in the past 50 to 60 years. In the year 2000, approximately one-quarter of the world”s population was myopic, but by 2050, it’s projected that about half of the planet’s population will be nearsighted.
This is a staggering figure. Myopia already affects nearly one-half of the United States’ and Europe’s population. In East Asia, about 80 to 90 percent of adults and teens have myopia.
In Seoul, South Korea, a full 96.5 percent of young 19-year-old men are myopic. These statistics cannot be explained by genetics alone, although myopia tends to run in families.
A child with one myopic parent has about a three-fold increase in the risk of myopia; a child with two myopic parents has almost double that risk.
Causes of Myopia
Besides genetics, what causes myopia? The answer to this appears to lie in lifestyle changes over the past 50 years or so. Although staring into smartphones, playing games, and doing online activities cannot be wholly blamed for the myopia pandemic, it plays a significant role.
Another factor is a lack of outdoor time for children. In the past, children spent more time outside and relatively little time doing close-up visual tasks.
Spending time outdoors and doing activities that don’t constantly require close-up vision are linked to a lower incidence of myopia.
Is Myopia Serious?
Although many parents and other adults consider myopia to be a minor issue correctable with eyeglasses and contact lenses, there is more to it than that. While mild degrees of the condition is probably not serious, higher ones may be.
High myopia, defined as a corrective prescription of -6.00 diopters or more, may be associated with a higher risk of retinal detachment, a serious medical condition capable of blinding.
Another condition called degenerative myopia affects about 2 percent of Americans. Also called malignant or pathological myopia, this hereditary condition not only progresses very rapidly and results in legal blindness, but it’s associated with a higher risk of retinal detachment and other degenerative changes in the back of the eye.
These changes may include the growth of abnormal blood vessels that break open and bleed, causing significant damage to the retina and surrounding area. High myopia and degenerative myopia are not the same conditions, but high levels of myopia in themselves may pose problems.
Treatment of Myopia
Mild myopia may require correction for specific activities like driving, seeing the blackboard at school, sports involving distance vision like tennis, and watching a movie or television.
In children, myopia may be slowed by several treatments:
These cause the eye’s pupil to dilate, partially disabling close-up vision and forcing the eye to focus more on the distance.
These use a special progressive lens featuring several focal points, reducing myopia by preventing too much close-up vision.
Ortho-k contact lenses
These are rigid gas permeable lenses worn only during sleep. They temporarily reshape the cornea so that vision will be clear for all or most of the next day.
The effect is temporary and must be maintained by wearing the lenses each night.
Ortho-k is a good solution for children too young for refractive surgery, especially kids active in sports. It also works well for adults who are either poor candidates for surgery or don’t want it.
Parents should realize that some young children with myopia may not even know it, at least not until they attend school and notice that other children can see what they cannot.
This is only one reason why kids need regular eye exams just as much as adults do.
LASIK uses an excimer laser to correct vision permanently. First, the surgeon creates a tiny flap in the cornea. The laser reshapes the cornea underneath, and then the flap is placed back into the correct position.
In the PRK procedure, the surgeon removes a small amount of corneal tissue to flatten the cornea and direct light rays more accurately onto the retina.
Phakic IOLs (intraocular lenses) are like permanent contact lenses. They’re surgically implanted into the eye. This differs from cataract surgery because the eye’s natural lens is left intact.
The phakic IOL procedure may be a good option for people with thin corneas or high myopia because these factors increase the chances of refractive surgical complications.
Find a Top Eye Doctor Near You
If you’re thinking about refractive surgery for yourself or a loved one, or want to find a great eye doctor for regular exams, we can help.
We work with a group of eye doctors practicing nationwide who are currently accepting new patients.
We’re available to help you locate a top-rated eye doctor right near you. Our doctors are all highly qualified and offer the latest in technology and patient care. Let us make it easy for you to find a great eye doctor. We’ll help you set an appointment, too.