Glasses Prescription Explained (9 Things you need to know eye prescription)

glasses prescription explained
How to Read an Eyeglasses Prescription glasses prescription explained
Different Stage of Our Eyes

When you often visit your eye specialist, you may get several points and symbolic signs there. You’ll get a specific number there also. These numbers are equally important and related to the shape of your eyes. 

Most often, we make mistakes in choosing the right glasses for us. Some people also forget to attach the proper powers to their wearer. Meanwhile, the eye prescription will help you to figure out and strengthen your vision power. It also reduced the chances of nearsightedness, farsightedness, or astigmatism, and many more. 

We know how important your vision and eyes are to you. To understand these affairs, we attach here the details of the glasses prescription explained. You can make sense of the number and clipping on your prescription chart also.

Glasses prescription chart Example

Before moving on to the deeper discussion, let us take a look at an example of a prescription chart. 

SPH CYLAxisAddPrism
OD -3.00SPH +2.000.5BD
OS-2.00-0.50180+2.000.6 BU

In the right eye (OD), the eye doctor/ specialist prescribed about:

  • -3.00 D sphere for the cure or correction of nearsightedness.
  •  The patient had no cylinder power or Axis. That is to mean the patient didn’t have astigmatism. This eye specialist often writes SPH to confirm the right being developed and prescribes only spherical power. Again, some physicians will add “DS” there for “diopters sphere,” and others leave it blank. 

About the detailedness of the left eye prescription chart (OS) 

  • -2.00 D sphere stands for nearsightedness correction. 
  • -0.50 D cylinder here specified there for astigmatism correction. 
  • A cylinder power stands here along with an axis at about 180 meridians: it is a horizontal (180⁰ degree) meridian of the eye. The number also symbolized that eyesight has no added power for astigmatism. Again, the vertical 90⁰ degree meridian gets the adjusted -0.50D from the cylinder column. 

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Here, both eyes are prescribed an “add power” of +2.00D for the treatment of presbyopia. Again, it means prismatic treatments for 0.5 prisms diopter in each eye. The patient’s right eyes are based on BD. On the left eye, it was relying on BU. 

OD vs. Os Prescription

OD vs. Os Prescription

OD and Os are the two medical symbols that the physician usually uses to define the condition of your eyes. The abbreviations of both OD & Os are denoted by your right and left eyes. In brief, OD is referring to the whole word of oculus Dexter. It is the Latin phrase for the right eye. 

Again, the word Os here define the short form of oculus sinister, which means left eye in Latin.

On the other hand, your eye prescription also contained the column labeled “OU.” It is an abbreviation of oculus uterque that means both eyes in Latin.

These abbreviated or symbolic terms are very general on the prescriptions for glasses. However, somewhere, you may find RE (right eye) and LE (left eye) instead of OD & OS. Your eye specialist prefers those signs this way when they face you because they see your right eye on their left and the left eye on their right.  

What does CYL mean for glasses?

CYL is a common sign that doctors or eye specialists often attach to their eye prescriptions. The complete form of cyl is the cylinder. The meaning of the cyl eye prescription is tracing the amount of lens power that is needed for astigmatism. It works to ensure the sphere power that you will find on an eyeglass prescription.

CYL is a common sign that doctors or eye specialists often attach to their eye prescriptions
CYL means Cylinder

Again, you can see the number mentioned in the cylinder column that contains a minus sign or a plus sign. Here, minus is for cure nearsighted astigmatism, and plus is for cure farsighted astigmatism

 If you didn’t find any number in the column section on the prescription that means you don’t have astigmatism. However, it is often defined that the patient has very little sufferer of astigmatism. 

Along with these, the term “cylinder” also defines the lens power added to correct astigmatism. It isn’t spherical. But the period is shaped and well-engineered so that one meridian doesn’t belong to any added curvature. 

The meridian perpendicular here stands for correct and correct astigmatism. Then, How does it work? The meridian perpendicular had no added power. This power will include maximum power and lens curvature. 

Meanwhile, the meridian of the eyes is worked by superimposing a protector scale on the eye’s front surfaces. (90⁰ meridian = vertical meridian of the eye, and 180⁰ meridian = horizontal meridian). 

What does SPH mean for glasses?

SPH generally stands on the prescription to measure the amount of lens power. It was prescribed to treat nearsightedness or farsightedness. The lens power is calculated here in diopters (D). 

How often do you define this? It’s pretty straightforward; you need to determine whether the prescription indicates a minus sign or not. Minus sign here will signify the problem of nearsighted patients. If you find the negative sign, it will define that you’re struggling with farsightedness. 

In a word, SPH means the correction of nearsightedness or farsightedness spherically. Or it was equal in all the meridians for the eye. 

What does Add mean for glasses?

The complete form of Add is the added magnifying power. It was applied to the bottom parts of the multifocal lenses as a treatment of presbyopia

Presbyopia is the natural farsightedness that happens with age. As we see in the prescription it is always a plus. The number always appears for these sites are positive. You’ll find a plus sign into the medicine if you’ve any problems like this. The specific range of ads is from +0.75 to ±3.00D. It will be equal power for both eyes.

What does Axys mean for glasses? 

Axys or glasses Axis are added in the prescription to describe that the patient has no lens meridian. Axys are also known as a sphere cylinder axis. Lens meridian means it will contain less cylinder power to correct astigmatism.

If your prescription includes the cylinder power, you’ll indeed find there an axis value. Axis values are always welcomed and measure the cylinder power. Axis power always exists from 1to 180. It never goes up to above this range. 

The number 90 assembles to the vertical meridian of the eye. Again, the number 180 forms the horizontal meridian of the eye. 

Keep in mind that the Axis is always the lens meridian. If it goes 90 degrees away from the meridian, that means it has contained the cylinder power for astigmatism correction. 

What does PD mean for glasses?

PD or PD, however, you see in the contact lens prescription or eye test prescription; always mean amount of prismatic power. The amount was measured in prism diopters. Doctors are always freehand to write this as p.d. or a triangle. It was usually prescribed to treat the patient’s eye alignment problems. 

Only a few eyeglass Rx prescriptions include this prism measurement. You will find the size in either metric or fractional English units. As an example, we can say 0.5 or ½. The doctor often indicated the directions of the prism. It will note the relative positions of its thickest edge of the base.

Four abbreviations are used for prism directions. These are: 

  • BU, which means, base up 
  • BD, which means, base down 
  • BI, which means, based in (it signifies toward the wearer knows)
  • BO, which means based out (it represents the wearer’s ears). 

In the word, Pd means personified fit that starts with measuring the pupillary distance. It measures the space between the centers of each of your pupils. Pd is always measured in millimetres.

It will also give the lens maker direction about where you need to put the optical centre for both lenses. Your doctor will include it, or you can measure it by yourself. 

How to measure glasses prescription

Both of these eye prescription terms are measured in quarter-diopter with 0.25D increments. Correspondingly, Sphere power, ADD, Cylinder power- all these are always measured in diopters. Axis is valued from the whole numbers from 1 to 180. It signifies only a meridional location, not an authority. 

Again, in the fact of the prism, diopters are also measured in decimal form. Typically, it will indicate only one digit appears after the period of 0.5.

Your prescription usually includes the following numbers: SPH, CYL, Axis, ADD, and pupillary distance

The first indicated parameter is always focused on your visual correction. PD is a vital measurement that your glass provider needs to make your glasses. 

Here we included in a list for which reasons these exist in your glasses prescription. 

SPH, CYL, Axis, ADD, and pupillary distance.
  • OD (oculus dexter) – directed your right eyes measurement 
  • OS (oculus sinister) – it indicates the number of your left eye’s parameters
  • SPH (sphere) measures the amount of lens power prescribed for nearsighted or farsighted vision. The numbers are always metering in diopters. It uses (+) for visionary and (-) for nearsightedness.
  • CYL & Axis are here to correct your astigmatism. Both are required together. They always consist of the number between 0-180⁰ degrees. 
  • ADD is an accurate provider of magnifying power that includes reading, bifocal, multifocal, and progressive eye lenses. Some people will be most likely to have the same number for both eyes. It usually ranges between +0.75 & +3.00. 
  • Traditionally, lower add powers than +0.75 can be found in most prescriptions. These are known as anti-fatigue lenses, such as our sight-relax lenses. 
  • Prism: there, you also find the prism that is measured in prismatic diopters. It is also traced in the prescription as a p.d in short. It is necessary when eye alignment needs assistance. We previously discussed its indications, such as BO, BO, BI, and BD. 

 Now, it may be quite an easy task for you to observe how to read optometrist prescriptions. The answer is now simple, as you’re able to find out the sections of your glasses prescriptions and figure out what all those signs mean. As though, 

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  • If you see (-) characters, it indicates nearsightedness prescriptions.
  • If you see (+) signs, it indicates farsightedness.
  • Whether you find their “add” power, it indicates the magnifying lenses as progressive. 

What to know about nearsighted prescriptions? 

What to know about nearsighted prescriptions? 
You may see in an eye exam diagnosis nearsightedness or myopia. It includes a refraction assessment and an eye health exam. 

You may see in an eye exam diagnosis nearsightedness or myopia. It includes a refraction assessment and an eye health exam. 

Nearsighted prescriptions will indicate the sign of (-). As an example, if your prescription says -1.00, you’ve one diopter of nearsightedness. It signifies more nearsightedness than -1.00, and it requires stronger / thicker lenses. 

Myopia generally occurs when the light enters the cornea, and it is deformed /sent to a spot in the eye before reaching the eyes’ retina. Nearsightedness will happen when the cornea and lenses receive light waves, sending them to the wrong place instead of the right one. The nearsighted people suffer from, 

  • Shortsighted, 
  • Unable to focus on the objects further away, 
  • Able to see things too closely and clearly. 

What to know about farsighted prescriptions? 

Farsighted prescriptions have equally signified the signs of positive (+)

Farsighted prescriptions have equally signified the signs of positive (+). Positive signs require that you’re a patient of hyperopic. As farsighted, people usually suffer from headaches or eye strain. It may squint or feel fatigued. Farsightedness prescriptions typically begin with the plus number, such as +2.50; you’re farsighted. 

A patient should wear glasses or contact lenses all the time while studying, working on a computer, or doing other work. They may also prescribe you to wear high-index lenses. 

High index lenses reflect more light than standard plastic lenses. If you found these signs in your prescriptions, then you may be the patient of farsightedness. 

What to know about astigmatism prescriptions? 

Astigmatism is an uncommon visionary problem for many people

Astigmatism is an uncommon visionary problem for many people. There are different sorts of reasons to work behind the problem. Most physiologists claim that they’re prominently genetic and can increase or decrease when the patient ages. 

The patients didn’t notice the symptoms with their naked eyes. Unlike nearsightedness or farsightedness, astigmatism isn’t a visible condition. You can find the signs in the prescription as though, 

  • blurry vision
  • Eye strain or squeezes 
  • A sidelong glance to see near or far images
  • Difficult to recognize the printed words
  • Double vision 
  • Headaches, etc. 

If you’re suffering from this syndrome, you’ll find both CYL and Axis values in the prescription for one or both eyes. You’ll trace plus or minus signs into the CYL sections. Remember, if your physician suggested the handwritten remedy, the CYL section would be the second series of numbers that followed the Axis. 

The axis number here represents the degree of the angle the cylinder is placed into the corrective lens. Your axis number always belongs to the whole number around 1 to 180.

For example, if your axis number is about 180, you need to place the cylinder horizontally on your lens. Most people found their prescriptions fall between these right angles; they’re nearly 180 or 90 degrees

Contact your optometrist if you cannot trace any axis number in the field, as this is likely an error. 

Hence, when you look at the Axis number on your prescription, you’ll find many zeros before the number, including 005 or 090. It translates the axis numbers 5 and 90. Here, the zeros are mentioned for clarity, easily distinguishing between 009 and 090.


Is 1.25 eye prescription bad?

1.25 eye prescriptions aren’t wrong. It is considered mild, and some people don’t need prescription eyewear for it. Again, the 1.25 range is a standard glass range for low to general-farsighted wearers. If the glass strength below 1.00 isn’t enough, lenses under the 1.00-2.00 range should do the job. 

Relatively, 2.25 is a high prescription for reading glasses. Many people find this range appropriate once they’re around 45-50 years old.  

What do the numbers on a glasses prescription mean?

The numbers on a glasses prescription mean they’ve signified the present condition of your eyes. When you go to the doctor, they usually give you a glass prescription to find different numbers. 

Like, you’ll find the numbers listed under the headings of OS & OD. They are Latin alternatives. Here, OS stands for oculus sinister, the left eye, and the OD (oculus textures) that refer to your right eye. Similarly, you’ll see a notation for OU, which means something involved to both your eyes

What does 2.25 mean for glasses?

If your prescription reads +2.25, that means your eyeglasses need 2.25 diopter of strength to correct farsightedness. Remember, the higher the number, the more correction your vision needs.

Again, 2.25 glasses are a mild number between +/- 2.25 to +/- 5.00. It is also required to moderate numbers. +2.25 also means that the patients belong to long-sightedness, so objects up close appear more blurred.

What does 0.75 eye prescription mean?

0.75 means the patients had hyperopia. Most people get a mild prescription, between 0.5~0.75D.

 It’s an average number of glasses for farsighted patients. 0.75 refers to the symptoms of your creative problem in a primary stage. The doctors prescribed it to the patients if they felt migrants on their forehead or faced difficulties seeing the objects further away.

It also shows the severity of astigmatism or informs you how the irregular cornea is shaped. It will measure in diopters like other eye numbers. 

Final Wrap 

The glasses prescription explained to you about the condition of your eyes. There you may find different information written by many optometrists or ophthalmologists regarding their experiences. The look is a sensitive part of the organ in our body.

Glasses help to minimize your creative problem. So, here we discussed only the basic information about the prescriptions. 

Remember, eyeglasses and contact lenses are different from each other. Do not spoil them by being considered equal. We hope this above information will help you in the long run. 

Remember, eyeglasses are always measured in diopters. And some eye specialists indicate the PD (pupillary distance) measurement on their prescriptions also. Justify your prescription first before giving it to any glass providers. 

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