What is normal BC for contacts?
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.
What is BC and DIA on contacts?
1. Base Curve (BC): the number that indicates your contact lens’ shape. According to the steepness or flatness of your cornea, your prescription indicates how large your contact lens should be. 2. Diameter (DIA): a number indicating your contacts’ length to make sure they’ll cover your cornea properly.
Is there a difference between 8.6 and 8.8 base curve?
A base curve of 8.6 mm of radius is more curved, and therefore a tighter fit, compared to the 8.8 mm base curve. People who have steeper corneas require tighter fitting contacts. If a contact is too loose, it may be uncomfortable, fold, or come right out.
Does the BC of contact lenses matter?
You should never order contact lenses with a base curve that is different from your prescription. This can damage your eyes and cause problems with vision. This is especially important for people who purchase cosmetic coloured contact lenses, which are often of a standardised size.
What is the most common BC for contact lenses?
The base curve, or BC, is the radius of the back of the contact lens, the part that sits on your eye 3. According to Laser Eye Surgery Review , the average measurement of a base curve is between 8.0 and 10.0 3. An example of a common base curve would be BC 8.7mm.
Does the BC on contacts matter?
How do I know my base curve?
Simple Rule for estimating lens base curve on a PLUS POWER lens
- For plus power use the spherical equivalent (SE) and add 4.00 diopters to that. For example, if you have an Rx of + 2.00 sphere, the base curve for the lens will be approximately 6.00.
- Rx +2.00Sph -> [+2.00 +4.00D] = 6.00BC.