What Is the Power of Contact Lens?

The power of contact lens, also referred to as SPH or D, is defined as the strength of the vision correction and can be either plus or minus. Plus power refers to farsightedness, or the inability to see objects close up. Minus power refers to nearsightedness, or the inability to see far away.

Power

• The power of contacts is often referred to as "sphere," which is measured by diopters. Power is identified in your prescription by positive or negative numbers.

Multifocal

• This term, also referred to as bifocals, describes the need to increase a contact lens power ratio by either adding additional power or removing power depending on the your needs.

Contributors

• Base curve, which is associated with the shape of the contact, plays a key role in determining your contact lens power. Diameter, the size of the lens in millimeters, also plays a vital role in identifying your overall power.

Warning

• Contact lenses are specifically prescribed to correct your vision needs, eye base curve and diameter. Do not wear lenses prescribed for others. This can cause severe damage to your vision.

Tip

• Do not order contact lenses without knowing your contact lens power ratio. You can obtain this from your eye doctor.