Hyperopia vs. Myopia: Understanding Two Common Refractive Errors
Eye Diseases & Conditions
Hyperopia and myopia are two of the most common refractive errors that cause vision impairment in Americans. Hyperopia, commonly known as farsightedness, and myopia, or nearsightedness,can cause significant visual impairment if left untreated, albeit in different ways.
Before we can properly explain the differences between hyperopia and myopia, we first have to understand their similarities. Farsightedness and nearsightedness are refractive errors, and exist as a result of irregularities in the physical size and shape of the eye.
Refractive Errors Are Not Diseases or Illnesses
Unlike eye diseases that affect vision,such as glaucoma, a refractive error is inherent in the physical structure of the eye. Refractive errors cannot be corrected via medications.
Refractive Errors Affect Vision Because of How They Influence Light
The job of your cornea/lens is to focus, or refract, light onto the retina (the part of the eye that contains the rod and cone cells that receive visual information). Irregularities in the size or shape of the eyeball and cornea/lens cause a refractive error, where light is not properly focused on the retina.
Why is Hyperopia Called Farsightedness?
Good question! As you can probably imagine, hyperopia gained its nickname because of how it affects your vision. People with hyperopia have difficulties when trying to focus close-up (like when using a computer), but have normal distance vision.
What Causes Hyperopia?
Hyperopia is caused by your eyeball being “too short” and thus preventing a normal refraction. As a result of this, light rays are sent by the cornea/lens to focus “behind” the retina- this is what causes close-up objects to appear blurry and out of focus.
How Hyperopia is Treated
Hyperopia is effectively corrected with prescription glasses, contact lenses, and refractive surgery.
Myopia is called nearsightedness because of how it impacts vision. People with myopia have impaired vision when looking at distant objects, such as passing road signs or looking at the front of a classroom, but have normal close-up vision.
What Causes Myopia?
Myopia is the result of your eyeball being too long, resulting in light focusing in front of the retina instead of directly on it. This is a progressive disease that can change rapidly, especially in kids (see myopia control).
How is Myopia Treated?
Myopia is treated with prescription glasses, contact lenses, laser refractive surgery, and myopia control (for kids).
Now that you know the basics hyperopia and myopia, you can better understand their differences.
While both refractive errors are just that – a refractive error – the main difference between them lies in the shape of the eyeball. Compared to a normal eye, an eye with hyperopia will be shorter and an eye with myopia will be longer.