Contact Lens Base Curve

Base Curve, or BC, values range from about 8.0 to 9.5. The doctor fits the lens with the curvature most appropriate for your eye. Most disposable contact lenses come in several different base curve values. If your prescription does not contain a base curve value, this is likely because your brand of lens only comes in one base curve.
base curve values are a bit like clothes sizes - just because you are a base curve 8.6 in one brand of contact lenses doesn´t mean you will be in another.

Base Curve

The base curve (BC) is a part of your contact lens prescription. It relates to the curvature of your eye and typically is a measurement in the range 8.0 to 9.5. Your doctor measures the curvature of your eye during your contact lens exam and chooses the base curve for your contacts appropriately.

New Law on Contact Lens Prescriptions

On February 4th this year, a new Federal Law called the “Fairness To Contact Lens Consumers” act went into effect. This law made it much easier for you to enjoy the savings and convenience of ordering on-line.

Your doctor is required to release your prescription once the fitting is complete (this may include the initial exam and one or more follow-up visits). Your doctor is not required to release an expired prescription and in any case we would be unable to dispense contacts from an expired prescription. Some doctors are more ready to comply with local laws than others.

Plus Powers & Minus Powers

Your contact lens precription contains a parameter called power (or sphere). This is the vision correction applied by the contact lens. If you are short sighted, this number will be positive, eg +1.5, if negative -, eg -2.5.

Contact Lens Prescriptions vs. Eyeglass Prescriptions

A contact lens prescription is very different than an eyeglass prescription. In addition to the lens power, your contact lens prescription contains several other pieces of information related to the size of the lens. These will include base curve, diameter, power, and experation date. Toric and bifocal contact lenses also contain more numbers specific to those types of lenses.

Contact Lens Prescription Expiration

A contact lens prescription is generally good for at least a year from the date it was issued - more in some states. However, your doctor can expire your prescription in less than a year if there are documented medical reasons why a shorter period is necessary. You must always provide a valid prescription for Prescription Contacts.