Myopia is a common refractive error, with an estimated 42% of Americans living with some degree of myopia.
It is known colloquially as nearsightedness (and less often, short-sightedness), a term that accurately describes the impacts myopia has on those that live with it: blurry, hazy, or otherwise impaired distance vision.
In this article we will provide a comprehensive high-level understanding of myopia, including its causes, symptoms, diagnosis, and treatments.
What is Myopia & Why Is It Often Called “Nearsightedness”?
Myopia is a refractive error, where a physical irregularity within the eye causes light that enters it to refract abnormally. This irregular refraction impairs vision and forces people with myopia to seek correction.
People with myopia, especially undiagnosed myopia, often strain to see clearly. If you are nearsighted, you probably have no problems reading or completing other visual tasks that are within close proximity; however, you will struggle to see distant objects (such as whiteboards or the TV).
Who Can Develop Myopia?
Myopia is fairly prevalent across all age ranges, sexes, and races. It can begin its progression as soon as early childhood and may progress throughout life.
There are some differences in the development of myopia in different races, ages, and sexes, but for the purpose of this article, it is understood that myopia has the potential to impact all Americans and is not isolated to one specific group.
Understanding Refractive Errors
The eye’s lens is an important structure, changing its shape as directed by the eye focusing muscles. Every time we strain to focus on an object, we exert pressure on the lens via our focusing muscles and that pressure slightly reshapes the lens.
This is because as light passes through the lens, it is focused on the retina. In an eye absent of refractive errors or other health concerns, the light is focused directly onto the retina and provides clear vision.
However, in an eye with a prominent degree of myopia, light does not focus directly on the retina. Instead, it focuses in front of the retina. This forces people with myopia to strain to bring vision into focus (ie, squinting) or to use corrective lenses or surgery to resolve the refractive error.
Myopia, like all refractive errors, is not an eye disease; it is caused by a physical irregularity in the eye, either with the shape and size of the eye itself, or in its lens.
Irregular Eye Shape
When the eye is too long (front to back), light that passes through the lens won’t be refracted appropriately. This will result in myopia, as light will refract in front of the retina as opposed to directly on top of it.
Excessive Curve of the Cornea
If the cornea is too curved, the resulting refraction also will not come to focus on the retina.
Other Potential Causes of Myopia
There is evidence that suggests that a reduction in natural sunlight exposure can influence myopia development as well.
One recent study, published in June 2015, found that exposure to sunlight may reduce myopia in infant monkeys.
Another study, published January 2017, found that exposure to UVB radiation (which we receive primarily as sunlight) correlated with reduced odds of myopia- especially in children and teenagers.
Myopia may develop slowly over time, obscuring its symptoms somewhat as the transition from proper sight to myopic sight occurs gradually. Symptoms of myopia may aslo present in areas outside of vision. In addition, myopia often begins developing in kids (who lack the frame of reference to know that something is wrong with their vision).
Because of this, we recommend regular eye exams for all Americans (and especially for children). Myopia is easily diagnosed during a comprehensive eye exam.
Visual Symptoms of Myopia
Blurry, hazy, or otherwise impaired vision of distant objects (for example: the whiteboard at the front of a classroom being blurry when seated at the back, or a distant road sign on a highway being difficult to read)
Difficulty with distance vision at night (sometimes referred to as “night myopia”)
Non-Visual Symptoms of Myopia
Squinting and straining when looking at distant objects
Headaches (a result of consistent eye strain)
Pain in neck, shoulders, and upper back
Because it is a refractive error, myopia is fairly easy to diagnose during an eye exam.
During the eye exam, the eye doctor will perform a series of tests using both automated diagnostic equipment and doctor-operated equipment. These tests will determine your visual acuity and whether or not you have myopia (and the degree of its progression).
Visual Acuity Test for Myopia
A series of letters and numbers are printed on a grid and placed at a distance of approximately 20 feet. From there, you are instructed by the doctor to read the letters and numbers.
Your performance during this test will help indicate myopia, but it may not be conclusive on its own.
Using a Phoropter
Looking through the phoropter, you are asked to provide visual feedback regarding the visual stimulus you are looking at (this stimulus may be a grid of letters and numbers, a picture, and so on).
The eye doctor will then adjust the phoropter’s lens powers, using your feedback to refine their adjustments until they have determined your myopia prescription.
Automated phoropters are also used to approximate myopia prescriptions, with the optometrist or ophthalmologist then fine-tuning the prescription by hand.
Retinoscopy is performed for non-verbal patients such as infants or those with special. This is an objective technique to diagnose the correct lens prescription in order to correct refractive errors.
Effective Treatments for Myopia
Myopia is usually successfully treated by correcting the refractive error. This is generally done via corrective lenses (eyeglasses or contact lenses) or surgery, though myopia control is an increasingly popular method of treating myopia.
Treating Myopia With Eyeglasses & Contact Lenses
The first method of vision correction that an optometrist or ophthalmologist will recommend for treating myopia is corrective lenses. Eyeglasses and contact lenses are straightforward methods of vision correction that are non-invasive (eyeglasses), pain-free, non-surgical, and very effective.
Corrective lenses work by altering the way light refracts, correcting the refractive error and thus restoring clear vision. This is true for both eyeglasses and contact lenses.
Corrective lenses are prescribed during an eye exam. The eye doctor will determine your exact prescription and then discuss your options. Depending on your prescription, both eyeglasses and contact lenses may be used to correct myopia.
Eyeglasses are prescribed first, with many wearers eventually incorporating contact lenses as a partial or complete replacement for eyeglasses. Contact lenses require a more comprehensive eye exam compared to eyeglasses, as a proper fit is essential in long-term comfort when wearing contacts. Learn more about contact lens exams and fittings.
Laser Refractive Surgery
More commonly referred to by the procedure name itself – LASIK – refractive surgery is a popular option correcting myopia. In fact, laser refractive surgery is one of the most common surgeries in America. In 2016, an estimated 613,000 laser refractive surgeries were performed nationwide (our eye surgeon, Dr. Woolfson, has performed over 80,000 procedures).
Its popularity stems from its effectiveness: over 95% of those who have had the surgery performed are satisfied in the outcome. Laser eye surgery is also quite safe, with a complication rate of sub-1%.
Laser refractive surgery is an effective long-term treatment for myopia. Unlike corrective lenses, which compensate for myopia but do not actually correct it, refractive surgery physically reshapes the cornea and eliminates the refractive error entirely.
Myopia Control has becoming widely popular with the increasing rate of myopia worldwide. . Using corneal reshaping therapy (CRT) also referred to as orthokeratology, specialized corrective lens prescriptions, oratropine eye drops are strategies that aims to reduce the progression of myopia.
Myopia control is more effective in kids than adults. Learn more about myopia control.