- Nearsightedness and farsightedness are common refractive errors
- Some environmental and health factors cause nearsightedness
- Many people do not know they are farsighted
- There are various treatment options available for nearsightedness and farsightedness
How to Tell if You are Nearsighted or Farsighted
An eye exam is an accurate way to determine whether you're nearsighted or farsighted. Depending on the severity of the condition, your doctor may prescribe one or more treatment options. These range from prescription glasses to vision correction surgery.
If you think you may be nearsighted or farsighted, see an optometrist or ophthalmologist for an evaluation. They can discuss your treatment options, such as glasses, contacts, or surgery.
Understanding the differences and causes of these conditions makes it easier to identify symptoms early.
What is Nearsightedness?
Nearsightedness or myopia is a refractive error that makes distant objects appear blurry. It occurs when the eyeball is too long, or the cornea is too curved, causing light entering the eye to refract in front of the retina.
Myopia affects both children and adults, although the numbers are higher among school-aged children. The American Optometric Association (AOA) estimates over 40% of Americans have this condition and projects a steady increase in the coming years.
An eye doctor performs several tests to determine how your eyes focus light during the initial diagnosis. One of the tests involves identifying letters from a vision chart to measure the sharpness of your vision within a 20-feet distance.
The doctor records the test results in a fraction format where the numerator is the standard test distance (20 feet). The denominator is the distance from which someone with normal vision can see an object, but they can only see the same object from 20 feet.
The doctor may also use a photoproter to test your vision. This device uses several lenses to measure the refraction of light entering your eyes. The results of this test determine the type of vision correction lenses you need.
What are the Symptoms of Nearsightedness?
The main symptom of nearsightedness is blurry vision when looking at faraway objects.
Other common symptoms of nearsightedness include:
- Squinting to see objects that are far away
- Difficulty watching TV or driving at night
- Headaches caused by eyestrain
- Eye tiredness when focusing on distant objects
- Trouble reading a whiteboard in school (children)
What Causes Nearsightedness?
Some environmental factors and health conditions can cause myopia. However, given the complexities of its diagnosis, additional studies are needed to confirm this.
For example, studies link myopia to gene mutations with at least seven variations in one type of gene. More than 200 genes are involved in the mutations that cause nearsightedness.
Other than gene mutation, common environmental factors may contribute to nearsightedness:
- Intensive work focusing on near objects
- Reading, writing, or working on a computer for many hours in a day
- Low-light environments that make it difficult for the eyes to focus on objects
- Night myopia caused by increased pupil size
Myopia can also result from health conditions like:
- Diabetes (variations in blood sugar levels)
- Blunt eye trauma
- Eye inflammation
What is Farsightedness?
Farsightedness is also called hyperopia. It is a refractive error that makes near objects appear blurry. This condition happens when light entering the eye refracts behind the retina instead of on the retina.
Farsightedness affects about 5 to 10 percent of Americans. However, most people never realize they have this condition because of its diverse symptoms, especially during childhood. For example, many farsighted people have blurry vision when looking at both close and distant objects.
Farsightedness is diagnosed through a comprehensive eye exam to determine how your eye refracts light.
Usually, vision screening tests that involve identifying letters on a chart don't effectively detect hyperopia. On the other hand, a comprehensive eye exam includes several tests, such as visual acuity, topography, eye health tests, refraction tests, and more.
What are the Symptoms of Farsightedness?
Because farsighted people experience different vision problems, the symptoms can be confusing. For example, some farsighted people may have blurry vision when looking at distant objects, a symptom that's generally associated with nearsightedness.
Besides consulting a doctor for proper diagnosis, you may be farsighted if you have some of these symptoms:
- General eye strain and discomfort when accomplishing certain close-up tasks, like reading or working on a computer
- Eyestrain when focusing on near objects
- Eye squinting
- Headaches caused by eyestrain
- Near objects appear blurry
- Burning sensation and ache around the eye
What Causes Farsightedness?
When light enters a normal eye, the cornea refracts it on the retina. The cornea is the clear, outer part of the eyeball that focuses light, helping you see clearly. It is dome-shaped, enabling it to refract light onto the retina. If the cornea is too flat, it refracts light behind the retina, causing near objects to appear blurry.
Farsightedness also occurs when the eyeball is short. This forces light to refract behind the retina. Other causes of farsightedness include:
- Other refractive errors such as astigmatism
- Loss of flexibility of the eye lens (presbyopia)
- Flattened cornea
How are Refractive Errors Diagnosed?
Myopia and hyperopia are examples of refractive errors. They are both caused by abnormal eye shapes that prevent it from refracting light onto the retina. Refractive errors happen when the cornea changes shape or when the eyeball becomes longer or shorter.
Retinoscopy can diagnose refractive errors. During this procedure, the doctor examines the retina to determine light refraction. The test is usually done by an optometrist. They use a handheld tool called a retinoscope, which consists of a beam of light, a condensing lens, and a mirror.
Note: Most optometrists use autorefractors now instead of retinoscopes. They’re more accurate and much faster.
Then, the optometrist directs the light into the eye and moves it vertically and horizontally to observe how the light reflects on the retina.
This procedure also doesn't require a response from patients, making it an effective option for those with communication difficulties, such as children.
Treatment Options for Nearsightedness and Farsightedness
Depending on the severity of the refractive error, a doctor may recommend one of the following treatment options:
Contact lenses create the first surface that refracts light entering the eye. As a result, they correct how the eye refracts light onto the retina.
Laser-assisted in situ keratomileusis (LASIK) is an eye surgery that corrects the shape of the corneal tissue. The surgery only takes about 10 minutes for each eye and effectively treats myopia, hyperopia, and astigmatism. This treatment provides a long-term solution for correcting many refractive errors.
Other Refractive Surgeries
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