Several visual difficulties are due to farsightedness, nearsightedness, astigmatism, or a mix of the three.
Nearsighted vs. Farsighted
It may be difficult to differentiate between nearsightedness and farsightedness. Generally, nearsightedness refers to being able to clearly see nearby things, while farsightedness refers to being able to clearly see only objects that are far away.
For a person to know if they are farsighted or nearsighted, they may test which objects within sight are the blurriest.
Nearsightedness
As mentioned earlier, nearsightedness, or myopia, refers to clearly seeing objects that are close. This also involves experiencing difficulties in seeing objects far away.
The eyes are responsible for converting light into visual images. When light hits the eyes, it moves from the cornea to the pupil and back to the retina, which handles the passing of the light off to the optic nerve. The optic nerve then relays electrical impulses toward the brain.
When a person is nearsighted, a refractive error is present. This means that the light cannot be focused properly on the retina.
These errors are related to eye shape. A person could be born with an overly rounded cornea or long eyeball, and it is also possible to develop new shapes over time and age.
The American Refractive Surgery Council also says that nearsightedness can be attributed to environmental issues, such as using mobile phones, computers, and electronic reading devices.
The primary symptom of nearsightedness is the clear blurriness that occurs when viewing objects from a distance. Due to the strain associated with forcing the eyes to focus throughout the day, a person with myopia could also experience eye fatigue, squinting, or headaches.
Farsightedness
Farsightedness, or hyperopia, refers to the ability to see distant objects and find nearby objects hard to see.
This condition is also based on the eye's shape. The lens and the cornea are eye parts that refract the light that enters the retina. When the retina receives light, it releases it to the optic nerve, which relays the signals to the brain.
Hyperopia is typically observed in cases of flat corneas or shorter-than-normal eyeballs. It is likely genetically inherited.
People who experience hyperopia could also experience squinting, headaches linked to reading or other activities that require nearby focus, and aching, burning, or pain around the eyes.
Normal Vision: Does It Exist?
The reality is that a normal vision does not exist. Each person has respective behavioral, lifestyle, and genetic factors that affect how well they can see at a specific time. These factors can also affect one's vision throughout the day.
Clinically speaking, the usual standard for vision assessment is 20/20 vision, which is usually measured through a visual acuity test. This figure means that one can see at 20 feet what healthy eyes can see at that distance.
For people with 20/50 vision, this means that this person should be 20 feet away from the object that a person with "normal vision" may view from 50 feet.
Individuals who are either nearsighted or farsighted may need correction through contacts, glasses, or laser eye surgery. This is because the eye does not independently correct its own shape. Contacts and glasses can help the eye correctly refract light, while laser eye surgery could physically correct farsightedness, nearsightedness, and even astigmatism.
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