Nearsightedness and farsightedness are very common — but essentially opposite — types of vision problems.
The biggest difference between nearsighted and farsighted vision is where objects appear in focus. Nearsighted people see close-up objects more clearly, while farsighted people see things in the distance more clearly.
Conversely, nearsightedness makes distant objects look blurry, while farsightedness blurs objects that are close to you.
Nearsightedness and farsightedness are not eye diseases. Instead, they’re called refractive errors — slight abnormalities that affect the eye’s ability to focus light.
After light enters our eye through the pupil, it needs to be neatly focused on a thin layer of tissue in the back of the eye in order for us to see clearly. This layer is called the retina.
When light enters the eye and does not focus properly on the retina, it causes blurry vision. The difference between farsightedness and nearsightedness is simply a matter of where this light focuses inside the eye.
The differences between nearsightedness and farsightedness
In a nearsighted eye, light focuses too far in front of the retina, instead of directly on it. This usually happens because the shape of the eyeball is too long from front to back, but it can also be caused by the shape of the cornea.
When light focuses in front of the retina, distant objects look blurry, but those nearby appear in focus.
The medical term for nearsightedness is myopia. Farsightedness — known as hyperopia — is the opposite of nearsightedness.
Farsighted vision is usually caused by an eyeball that's too short, causing light to focus behind the retina. Farsightedness makes close objects look blurry, but high levels of hyperopia can cause objects at all distances to appear out of focus.
Alternatively, astigmatism can cause blurry vision at all distances.
Mild cases of farsightedness might not affect your vision at all. However, they can lead to headaches when reading or doing other close-up work.
Children with farsightedness are usually born with the refractive error. In many cases, childhood hyperopia improves as the eyeball lengthens with normal growth and development.
Nearsightedness, on the other hand, usually develops during childhood and worsens during adolescence. It then stabilizes during early adulthood.
About four times as many people have myopia versus hyperopia. Approximately 40% of Americans are nearsighted, while only 5-10% are farsighted, according to the National Institutes of Health (NIH).
The similarities between nearsightedness and farsightedness
While the specifics are different, nearsightedness and farsightedness can both be caused by either the shape of the eyeball or the steepness of the cornea.
The two types of refractive error can also share common symptoms, including:
Headaches
Eye strain
Squinting or straining to see clearly
Fatigued, “tired” eyes
If you experience any of these symptoms, be sure to schedule a comprehensive eye exam with an eye doctor.
Both nearsightedness and farsightedness can be treated with prescription eyeglasses or contact lenses. In both cases, these corrective lenses improve vision by changing the way light enters the eye. This allows light to properly focus on the retina.
Many people with refractive errors find that their vision stabilizes once they’re in their 20s. Once any refractive error has stabilized, procedures like LASIK or PRK may be able to permanently correct either condition by reshaping the thin layer in front of the pupil (cornea).
Source: allaboutvision.com
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