Explain Base Curve on Contacts

The base curve is an important part of your contact lens and prescription. The curvature of the lens is determined by the size of your eye and is measured by your eye doctor during your contact lens fitting.

Significance

• The base curve of your contact lens is the actual curvature of the lens and is measured in millimeters.

Identification

• During your eye examination and contact lens fitting, your eye doctor will use an optical instrument called a Keratometer to measure the curvature of your cornea (the front surface of your eye).

Size

• The size of the base curve is written in millimeters. The most common range is 8.0 to 9.0. Different contact lens manufactures make their lenses with unique curves and sizes, so the number may vary from lens to lens.

Curvature

• The steepness of your cornea is reflected in the number and size of the base curve. The steeper your eye, the lower the number.

Considerations

• Adjustments to the base curve may be necessary after you wear your lenses for a while. The curve of your eye and fit of the lens can change.