Understanding Sphere Power in Contact Lens Prescriptions

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.