Home My Eye Health What is Myopia, Hyperopia, Astigmatism, Presbypia?
What is Myopia, Hyperopia, Astigmatism, Presbypia?

One’s eyes can be myopic, hyperopic, astigmatic, presbyopic or a combination.  Your eye doctor will check your prescription and this will determine your refractive state.  Below is an explanation of the different refractive states.

 

Refractive Conditions

 

 

Myopia (nearsightedness)

 

Myopia is a refraction condition that is caused by the eye elongating beyond the normal length or the eye’s power is too strong.  When the eye grows longer than normal the image in the eye is focused in front of the retina.  If the eye’s power is too strong then the image is focus in front of the retina.  This will cause blurred vision at distance and clear vision at near.  So a person with nearsightedness is visually designed to see clearly at near.

 

There is a strong inheritance pattern to nearsightedness.  There is also a link between nearsightedness and industrialized countries like the United States.

 

Treatment for myopia (nearsightedness) is glasses, contact lenses or refractive surgery.

 

Hyperopia (farsightedness)

 

Hyperopia is a refraction condition that is caused by the eye not growing to the normal length or the eye’s power is too weak.  When the eye is too small the image of the image is focused behind the retina.  If the eye’s power is too weak then the image is focused behind the retina.  This means that the eye has to focus to bring the image of the world into clear view.   The eye is more comfortable and will see better at distance then at near.  So when one has to focus at near this will typically cause eye strain, blurred vision, headaches and possible double vision.  The image may still be clear however, the eye has to work overtime to make the vision good.

 

Patients that are hyperopic often require reading glasses.  However, if the hyperopia is moderate to high then glasses for full time wear are typically prescribed.

 

As one ages, especially around the age of 40, hyperopic patients will notice a decrease in their near vision.  This is because between the ages of 40-42 one enters into presbyopia and loses the ability to focus at near.  This is normal and happens to everyone, however, farsighted people are more affected by this change.

 

Treatment for hyperopia (farsightedness) is glasses, contact lenses or refractive surgery.

 

Astigmatism

 

Astigmatism is when the eye is oblong.  This causes a distortion in one’s vision at both distance and near.  Think of the eye as a basketball.  When one steps on the basketball it becomes oblong, just like astigmatism.  Another comparison is that astigmatism is similar to the shape of a football, oblong.

 

Treatment for astigmatism is glasses, contact lenses or refractive surgery.

 

 

Presbyopia

 

Presbyopia occurs when the lens loses its ability to change shape and focus at near.  This is a slow process which starts around the age of 42 and stops around the age of 60.  It is at this time in one’s life that they will notice things at near just aren’t as clear as they once were (blurred near vision.)  One will tend to hold reading material farther away.   The treatment for presbyopia is reading glasses, bifocal glasses or monovision contact lenses or bifocal contact lenses.

 

Refractive surgery will not fix presbyopia.   Everyone will lose the ability to focus at near.  Refractive surgery can only correct vision for a specific distance, either distance or near.  Most people want their distance vision clear.  However, there is a procedure called mono-vision where one eye is corrected for distance and the other eye corrected for near.  This and initial be difficult to adapt to however, one will test mono-vision out with contact lenses prior to refractive surgery.

 

 

 

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