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What is CYL, AXIS and SPH in eye prescription?

Lensmart 2021-09-08 14:52:29

When we look at the eye prescription written by our consultant, different questions come to mind. 

What is CYL, AXIS and SPH? This is an important question because this is related to the eyes and gives answers related to different changes in the human eye. The CYL stands for “Cylinder”. The AXIS stands for “Axis” and SPH stands for “Sphere”. 


Chart of CYL, AXIS and SPH

All these are used for the distance correction measurement. There are two vision conditions, nearsightedness, and farsightedness. 

In nearsightedness, the person can see those objects clearly which are near to him but the far objects are blurry. On the other hand, in the farsightedness, the person can see those objects clearly which are far but near object seems blurry. The sphere is the indication of how strong the lenses need to be in order to correct the vision. The cylinder is the indication of the condition, astigmatism, in which the cornea is shaped irregularly causing distorted or blurred vision. The axis is the astigmatism orientation. The 20/20 vision is the correct vision for normal eyes. This means that a person can see the object clearly at 20 feet.


What is normal eye CYL?

Cylinder is the indication of the lens power amount that is basically needed for the eyes disease named “astigmatism” (blurred vision). In astigmatism, the curvature of the eye is imperfect. How to read eye prescription? This is a common question when the person who consults eye specialists encountered the eye prescription. On the prescription of eyeglasses, the cylinder typically follows the sphere power. On the eye prescription, there are minus and plus signs in the cylinder column.


normal eye cyl vs abnormal eye cyl



What is normal eye AXIS?

In AXIS, the lens meridian plays an important role. The interesting fact is that if the prescription of eyeglass includes the main cylinder power, it is important to include the axis value along with it so that it follows the power of CYL. The axis depicts the angle between two meridians. The numbers are from 1 to 180 in the axis part of the eye prescription. In the vertical meridian of the eyes, the number 90 is used. In the horizontal meridian of the eyes, the number 180 is used.



normal eye axis vs abnormal eye axis


What is normal eye SPH?

Sphere means the spherical correction where the meridians of the human eye are equal. It does not matter whether the correction is of farsightedness or nearsightedness; it is always in spherical form. The lens power amount is, therefore, measured in D (diopters) for farsightedness or nearsightedness. When the person has no astigmatism, the perfect eye shows 0 diopters. Those individuals having 1.5 or more diopters will definitely need to use eyeglasses in order to correct the vision. 



normal eye sph vs abnormal eye sph


FAQ about CYL, AXIS and SPH

1. In eye prescription, what does CYL means?

The CYL basically represents the main differences in the weakest as well as greatest eye powers which are usually separated by degrees (90).


2. Is CYL bad or good to know?

On the eye prescription, CYL represents the cylinder correction part whether there is astigmatism or not. If there is no number written under the CYL part, this means you are free from astigmatism and need no eye contact. If the number is written, this is the indication of the usage of eye contact. CYL is good to know because it tells how light refracts on the eye’s retina.


3. Can the human eye axis change?

When the shape of the human eye cornea changes, the large changes in the measurement of the axis is seen though, this is rare. If the axis changes by more than 90, you need to consult an eye specialist.


4. What is the human bad eye axis?

If the human eye acuity is 20/200, this is called the bad eye axis and is considered the blind person. If the glasses help to improve the vision, then the person is not legally blind.


5. In SPH, the minus sign is an indication of which condition?

In SPH, the minus sign is the indication of nearsightedness (far away objects are blurred).


6. In SPH, plus sign is an indication of which condition?

In SPH, the plus sign is the indication of farsightedness (near objects are blurred).





Recommended article:

How to measure your PD (pupillary distance) at home?

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