What is the contact lens base curve?

The base curve of a contact lens is the curvature of the back surface of the lens. It determines the type of fit the lens must have to match the natural curvature of your eye.

It is usually expressed in millimetres and may be further characterised as steep, median, or flat.

Typical base curve values range between 8.0 and 10.0 mm, though it can be flatter (from 7.0mm) if you have a rigid gas-permeable lens.

A person with a higher base curve number has a flatter cornea (the clear, front surface of the eye) compared to someone with a lower base curve number, which indicates a steeper cornea.

When choosing contact lenses for vision correction, there are a number of important factors to consider. One of them is optimum fit, which is helped largely by making sure you order the exact prescription your optician has given you: this will ensure that the contact lens fits well on your eye.

Wearing poorly-fitting contact lenses can damage the eye and cause problems such as blurred vision, headaches, and eye strain. The diameter and base curve of a contact lens are two measurements that affect how well they fit your eye.