Myopia, also known as nearsightedness, is a common condition affecting approximately 23% of the population worldwide. Like hyperopia (farsightedness) and astigmatism, myopia is a type of refractive error. As the name implies, nearsighted individuals are better able to see close-by objects and have trouble with distant targets.
Myopia is a common vision condition that impacts the ability to see well at a distance.
Genetic and environmental factors contribute to the risk of developing this condition.
Myopia is diagnosed by an optometrist or ophthalmologist during an eye exam.
Treatments include glasses, contact lenses, orthokeratology lenses, and refractive surgery.
Symptoms of myopia
The primary – and often only – symptom of nearsightedness is blurry vision when viewing distant objects. This can cause problems with driving, seeing the board in class, or watching television, for example. Near vision is usually not a problem.
Other symptoms of myopia may include:
- Squinting in an attempt to see distant objects.
Causes of myopia
Light entering the eye should normally focus on the retina, the light-sensitive tissue inside the eye. Myopia is a type of refractive error, which describes a problem where light doesn’t focus accurately on the retina.
In myopia, light focuses in front of the retina. This is a result of the eye being too long, the corneal being too curved, or both. In any case, the result is blurred vision when viewing faraway objects.
Risk factors for myopia include genetics and environmental factors.
Nearsightedness tends to run in families. However, its development is also influenced by environmental conditions. Children who spend extended periods of time doing near work, and/or who don’t spend much time outside, may be at an increased risk of myopia.
Diagnosis of myopia
Nearsightedness is diagnosed during an eye exam. Your doctor may use several tools to do so.
- Visual acuity
Your visual acuity will be measured by having you read letters on an eye chart. In myopia, it is expected that the distant letters will be blurry, while the near ones will be clear.
The phoropter is the machine that is positioned in front of your face as you view the eye chart. It contains lenses that are presented to you to assess their impact on your vision. As part of the process called refraction, you may be asked for feedback on which lenses you prefer to look through.
Treatment of myopia
There are several options for the treatment of myopia.
Glasses and contact lenses
Eyeglasses and contact lenses are the most common treatment for myopia. These lenses help to focus the light on the retina, clearing up blurry vision. If there is minimal myopia, glasses may only need to be worn for certain activities, like driving. In higher amounts of myopia, glasses need to be worn full-time. Glasses and contact lenses compensate well for myopia, enabling clarity of vision, but they don’t treat the underlying cause.
Orthokeratology involves wearing hard contact lenses at night. These specially designed lenses apply pressure to the cornea, the clear tissue covering the front of the eye. This results in a reshaping of the cornea over time. By reshaping the cornea, myopia is lessened and vision is improved.
After the lenses are worn overnight, they’re removed in the morning to allow for clear vision during the day. Orthokeratology lenses generally need to be worn every night in order to maintain clear vision throughout the day. In addition to temporarily correcting vision, orthokeratology may also help to slow the progression of myopia in children.
Atropine is an eye drop that dilates the pupil. Atropine doesn’t clear up vision in myopia; in fact, it can make it blurrier. However, atropine can be used in children to slow the progression of myopia.
Vision correction surgery
Refractive surgery is another option to treat myopia. The most common laser surgeries used to correct myopia are laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).
Both procedures involve the use of a laser to reshape the cornea, correcting how light focuses on the retina. In addition to laser-based procedures, there are other surgical options.
For example, some people have a lens implanted inside the eye in order to clear up vision. Called an implantable collamer lens (ICL), it is placed in front of the natural crystalline lens already present in the eye.
Another option is to have the natural crystalline lens removed and have an intraocular lens (IOL) implanted in its place. This is called a clear lens exchange. It’s the same procedure as cataract surgery, but it’s done before a person develops a cataract.
Risk of myopia
High myopia may increase the risk for retinal detachment. Highly myopic individuals tend to have long eyes. This stretches the retinal tissue lining the eye, making it more prone to detaching. Regular dilated eye exams are especially important in high myopia so the doctor can check the retina for any problems.
- Ophthalmology. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050.
- American Optometric Association. Myopia (Nearsightedness).
- American Academy of Ophthalmology. Nearsightedness: What Is Myopia?