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Are contact lens and eyeglass prescription the same?
Contact lens prescriptions and eyeglass prescriptions are not the same.
They are significantly different because eyeglass lenses are positioned approximately 12 millimeters from your eyes, whereas contact lenses rest directly on the surface of your eyes.
What's The Difference Between A Contact Lens And Glasses Prescription?
Your prescription of contact lens contains specific information to ensure your contact lenses are safe, comfortable and provide optimum vision.
Here are the definitions of the symbols/abbreviations used in a typical contact lens prescription
Regular Prescription
1. Sphere (SPH)
Strength of your contact lens. This can also be referred to as Power(PWR) or strength.
Measured in diopters and always preceded by - (minus) or + (plus).
The minus sign means correction for nearsightedness(myopia) and the plus sign means correction for farsightedness(hyperopia).
If your prescription shows the letters PL, which stands for Plano, it means the no correction is needed.
- OD(Oculus Dexter): The Latin term for the right eye.
- OS(Oculus Sinister): The Latin term for the left eye.
- OU(Oculus Uterque): The Latin term for the both eyes. It means the prescription is the same measurement in both eyes.
* Most terms on contact lens prescriptions are measured in diopters. Diopter is often abbreviated as D.
2. Base Curve (BC)
The curvature on the inside of your contact lens.
This number is measured in millimeters. Usually 8.x.
For best fit, comfort, and eye health it’s prescribed to match or complement the curvature of your cornea.
The lower the number, the steeper the curve of your cornea.
3. Diameter (DIA)
Size of the contact lens.
It’s the distance, measured in millimeters, from one edge of your contact lens to the other edge.
Most brands come in a couple of sizes. Usually a 14.x number but can be from 13.x to 15.x.
This measurement is very important, because it determines where on your eye the edges of the contact lens will rest.
If the diameter is wrong, irritation or abrasion can result.
Toric for astigmatism
Some patients require contact lenses that are toric or astigmatism correcting.
Prescriptions for these types of contact lenses will contain two additional information that relate to the correction of the astigmatism.
4. Cylinder (CYL)
Measured in diopters, the cylinder shows the extent of your astigmatism.
It is necessary if your contact lenses are for the correction of astigmatism.
Always a minus number.
5. Axis. (AX)
The axis is a necessary measurement for contact lenses that correct astigmatism.
The axis is measured in degrees and indicates the orientation of the cylinder in the lens.
It will be between 0 and 180 degrees.
Additional Contact Lens Prescription Notes
- Your prescription will also contain an expiration date. This is typically one to two years from the date that the contact lenses were fitted.
Are contact lens and eyeglass prescription the same?
Contact lens prescriptions and eyeglass prescriptions are not the same.
They are significantly different because eyeglass lenses are positioned approximately 12 millimeters from your eyes, whereas contact lenses rest directly on the surface of your eyes.
What's The Difference Between A Contact Lens And Glasses Prescription?
Your prescription of contact lens contains specific information to ensure your contact lenses are safe, comfortable and provide optimum vision.
Here are the definitions of the symbols/abbreviations used in a typical contact lens prescription
Regular Prescription
1. Sphere (SPH)
Strength of your contact lens. This can also be referred to as Power(PWR) or strength.
Measured in diopters and always preceded by - (minus) or + (plus).
The minus sign means correction for nearsightedness(myopia) and the plus sign means correction for farsightedness(hyperopia).
If your prescription shows the letters PL, which stands for Plano, it means the no correction is needed.
- OD(Oculus Dexter): The Latin term for the right eye.
- OS(Oculus Sinister): The Latin term for the left eye.
- OU(Oculus Uterque): The Latin term for the both eyes. It means the prescription is the same measurement in both eyes.
* Most terms on contact lens prescriptions are measured in diopters. Diopter is often abbreviated as D.
2. Base Curve (BC)
The curvature on the inside of your contact lens.
This number is measured in millimeters. Usually 8.x.
For best fit, comfort, and eye health it’s prescribed to match or complement the curvature of your cornea.
The lower the number, the steeper the curve of your cornea.
3. Diameter (DIA)
Size of the contact lens.
It’s the distance, measured in millimeters, from one edge of your contact lens to the other edge.
Most brands come in a couple of sizes. Usually a 14.x number but can be from 13.x to 15.x.
This measurement is very important, because it determines where on your eye the edges of the contact lens will rest.
If the diameter is wrong, irritation or abrasion can result.
Toric for astigmatism
Some patients require contact lenses that are toric or astigmatism correcting.
Prescriptions for these types of contact lenses will contain two additional information that relate to the correction of the astigmatism.
4. Cylinder (CYL)
Measured in diopters, the cylinder shows the extent of your astigmatism.
It is necessary if your contact lenses are for the correction of astigmatism.
Always a minus number.
5. Axis. (AX)
The axis is a necessary measurement for contact lenses that correct astigmatism.
The axis is measured in degrees and indicates the orientation of the cylinder in the lens.
It will be between 0 and 180 degrees.
Additional Contact Lens Prescription Notes
- Your prescription will also contain an expiration date. This is typically one to two years from the date that the contact lenses were fitted.
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