What Is Sphere in a Contact Lens?

'Sphere' is a number measurement that reflects your distance vision.

Contact lens prescriptions contain different numbers that have specific meanings and reflect the size and vision-correction strength of your lenses. "Sphere" is one of the categories of numbers.

Features

Sphere is the number and measurement that reflects nearsightedness or farsightedness.

Identification

Sphere can be written as SPH, Power or PWR on a contact lens prescription.

Considerations

Contacts can be simply a sphere correction, or they also may have another set of numbers for astigmatism, an irregular curvature of the cornea.

Nearsighted Sphere

Sphere power for nearsightedness is written with a (-) minus sign.

Farsighted sphere

Sphere power for farsightedness is written with a (+) plus sign.

No Sphere Power

Sphere also can be a zero or written as "plano" or "PL," if your contacts are toric and only correct for astigmatism.

References

• Ohio State University Medical Center: Glasses and Contacts

Resources

• Allaboutvision.com: Uncomfortable Contact Lenses