What is Myopia (Nearsightedness)?
Myopia, also called nearsightedness, is difficulty seeing faraway objects. It’s a type of refractive error.
When you have a refractive error, your eyes don’t properly focus images onto the retina. This causes objects to appear blurry. Myopia causes blurry distance vision, even if you can see nearby objects clearly.
Studies estimate that more than 40 percent of people in the United States have myopia.
Nearsightedness typically develops in childhood, between ages 6 and 14. It can worsen during adolescence, but usually stabilizes between ages 20 and 40.
Rarely, a severe form of nearsightedness called degenerative myopia can cause worsening far vision into adulthood.
Myopia (Nearsightedness) Symptoms
General symptoms of nearsightedness include:
- Blurred vision when looking at faraway objects
- Clear vision when looking at nearby objects
- Eye strain
- Squinting
- Headaches
Symptoms vary depending on how strong your prescription is. For reference, diopters (D) are the units eye doctors use to measure eye prescriptions.
Myopia Types
We can divide myopia into three categories based on severity:
- Low myopia is -3.00 D or less
- Moderate myopia ranges between -3.25 to -6.00 D
- Severe myopia is anything above -6.00 D
Generally, patients with low myopia only need to wear glasses to see far away. They don’t need to wear glasses for near activities.
Patients with moderate to severe myopia usually need to wear glasses full-time since they can only see objects that are very close to their faces.
Nearsighted patients over 40 will notice that they cannot see up close while wearing their glasses. Your eyes lose the ability to focus on nearby objects with age. This condition is called presbyopia.
These patients can remove their glasses to read. Alternatively, they may choose to use bifocal or progressive eyeglasses.
What Causes Myopia?
Myopia occurs when the focusing power of your eye is too strong. This causes images to focus in front of your retina. There are two ways this can happen:
- You have a longer eyeball length than average
- Your cornea, the clear covering in front of your eye, is too steep
Myopia and Genetics
The genetics of myopia is complex. The risk of myopia is greater in children of nearsighted parents. However, the parents don’t need to be nearsighted to have a myopic child.
Degenerative Myopia
Degenerative myopia is rare, but it can cause severe nearsightedness. Also known as malignant or pathological myopia, this type is usually hereditary.
People with degenerative myopia have an increased risk for complications, such as:
- Glaucoma
- Retinal detachment
- Choroid neovascularization (abnormal blood vessels in the eye)
Lifestyle Factors
Myopia is also influenced by external factors such as lifestyle. Research shows an increase in the prevalence of myopia with higher amounts of near-work activities. Common examples of near-work activities include reading and computer use.
Other studies found that myopia risk decreases with an increase in outdoor activity. The theory is that spending time outdoors in natural light can slow or prevent nearsightedness.
For these reasons, eye doctors recommend that school-age children spend less time looking at digital devices and more time enjoying the outdoors.
Risks of Myopia
Severe myopia not only affects your ability to see but can increase your risk for certain eye diseases, including:
Without treatment, even mild to moderate myopia can negatively affect daily life. Complications of nearsightedness for children and adults include:
- Chronic eyestrain and headaches
- Difficulty performing and interacting at school
- Impaired safety, especially while driving or operating machinery
Diagnosing Myopia
In Children
Most cases of myopia are diagnosed in childhood. Because children won’t necessarily complain of blurry vision, routine vision screenings are important.
Your pediatrician should check your child’s eyes at every well-visit. If you or your pediatrician notice any vision problems, your child may need to see a pediatric eye doctor.
If your child is unable to read the letters on an eye chart, an ophthalmologist can use a retinoscope. This device allows doctors to measure where light is aimed inside the eye. An ophthalmologist can use this measurement to determine your child’s eyeglass prescription.
In Adults
Your eye doctor can diagnose myopia during a basic eye exam. This includes:
Refraction Assessment
A refraction assessment helps your doctor diagnose vision problems, including:
- Myopia (nearsightedness)
- Hyperopia (farsightedness)
- Astigmatism
- Presbyopia
Your doctor will ask you to look through various lenses to check your close-up and distance vision.
Eye Health Exam
Your doctor will likely administer eye drops to dilate your pupils. Dilation provides your doctor with a better view of the inside of your eyes. Dilation also makes your eyes more light-sensitive, but this goes away after a few hours.
Myopia Treatment
The most common treatment for myopia is vision correction with glasses or contact lenses. Managing myopia also involves routine screening for common complications, such as cataracts.
Corrective Lenses
Prescription corrective lenses are the standard treatment for myopia. Types of corrective lenses include:
- Eyeglasses. Many types of eyeglass lenses are available, including single vision, bifocals, and progressive multifocals.
- Contact lenses. Contacts come in soft and rigid gas permeable lenses. They’re worn in your eyes and come in a variety of types. Your eye doctor will help you choose the best contacts for you.
Refractive Surgery
Many types of refractive surgery can treat nearsightedness. Some of the most common procedures include:
LASIK
Laser-assisted in situ keratomileusis (LASIK) is the most common type of refractive surgery. During a LASIK procedure, your eye surgeon cuts a small flap in your cornea. They use a laser to reshape your corneal tissue, then replace the flap.
LASEK
Laser-assisted subepithelial keratectomy (LASEK) is similar to LASIK. During LASEK, your surgeon creates a thin flap in the outermost layer of your cornea (epithelium). They reshape the outer layers of your cornea, then close the flap.
PRK
Photorefractive keratectomy (PRK) involves completely removing the epithelium.
After your surgeon reshapes your cornea, they apply a temporary contact lens. This lens protects your cornea until the epithelium regrows naturally. When your epithelium grows back, it conforms to the new shape of your cornea.
Laser eye surgery is FDA approved to treat up to -12.00 D of myopia. In some cases, if your prescription is high and your corneas are too thin, you may not be eligible for laser eye surgery. Instead, your surgeon may perform one of the following procedures:
Refractive Lens Exchange
This procedure removes the natural lens in your eye, which is very similar to cataract surgery.
The surgeon implants an artificial lens that corrects your myopia. This surgery is an ideal option for patients with high myopia and who may develop cataracts soon. With a refractive lens exchange, you will not need cataract surgery later in life.
Phakic Intraocular Lens Implant
The main difference between this procedure and a refractive lens exchange is that your natural lens stays in place. Instead, the surgeon will place an artificial lens in front of your natural lens. Or, the surgeon may place the implant in front of the iris.
This surgery is an excellent option for high myopia. Currently, it is not FDA-approved for other refractive errors such as hyperopia.
Treatments that Slow Myopia Progression
Some treatments that can help slow the progression of myopia include:
Orthokeratology (Ortho-K)
Orthokeratology involves wearing hard, gas-permeable contact lenses for several hours or overnight. Multiple studies suggest that using these overnight lenses slow down the progression of myopia, versus wearing eyeglasses alone.
The lenses temporarily reshape your corneas while you sleep. After removing the contacts, you can see reasonably well without glasses. Your corneas will resume their original shape after a day or two, so you will need to use the lenses regularly.
Multifocal Contact Lenses
These contacts correct up-close and distance vision. They may help slow myopia progression in some people.
Atropine Eye Drops
Atropine eye drops are what your eye doctor uses to dilate your pupils. At various doses, atropine drops may help slow the progression of nearsightedness.
Summary
- Myopia is a common condition that often develops in childhood and stabilizes during the adult years
- Myopia causes difficulty seeing distant objects
- Genetic and lifestyle factors can contribute to nearsightedness
- An ophthalmologist can diagnose myopia with a basic eye exam
- Nearsightedness is treated with eyeglasses, contact lenses, or surgery
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