What does Base Curve (BC) mean?

Answer 1

BASE CURVE -

Base curve radius, abbreviated BCR or BC, is a parameter of a contact lens. Typical values are from 8.0 to 10.0 mm. The base curve is the radius of the sphere that the back of the contact lens describes. Contact lenses must fit well to the wearer's cornea in order to be comfortable and to facilitate tear exchange and oxygen transmission.

In the case of a rigid lens spherical equivalent may not be used. This is due to the lenses ability to retain tears under the lens that will correct for the astigmatism. Soft disposable lenses do not have this feature. They tend to drape over the cornea conforming to its shape. This brings us to the next set of numbers.

After the lenses power we come to the Base curve. This number is the measurement of the radius of curvature in millimeters of the inside curve. The doctor does his best to try and match the lens curvature to the corneas. As mentioned earlier a soft lens tends to drape the cornea. Because of their flexible nature soft lenses tend to fit more corneas with the a smaller number of base curves. Often a lens manufacturer will only make a soft lens in a few curves. Rigid lenses on the other hand need to have a more accurate fit. Because of their rigid nature a lens that is too steep or too flat may cause discomfort.

After the base curve we come to the lenses diameter in millimeters. Like the base curves soft lenses come in a limited amount of diameters. This is due to their rather forgiving nature when it comes to fitting. Again like base curves the doctor will be more precise in specifying the diameter of a rigid lens. If looked at from a side view we see that the cornea projects further than the rest of the eye. The area were the cornea meets the sclera (the white part) is called the Limbus. As the eye blinks and rotates the contact lens will move. The soft lens well cover the limbus. The lenses movement generally will not cause irritation. With a rigid lens it should be small enough to allow lens movement with out running into the limbus causing irritation....

Answer 2

Contact Lenses Bc Meaning

Answer 3

Base curve radius, abbreviated BCR or BC, is a parameter of a contact lens. Typical values are from 8.0 to 10.0 mm. The base curve is the radius of the sphere that the back of the contact lens describes. Contact lenses must fit well to the wearer's cornea in order to be comfortable and to facilitate tear exchange and oxygen transmission.

In everyday practice, if contact lenses feel "loose" and slide easily a smaller base curve may work better. A large base curve may be needed if they feel tight. Lenses with smaller base curves are referred to as "steep".

Answer 4

Base curve radius, abbreviated BCR or BC, is a parameter of a contact lens. Typical values are from 8.0 to 10.0 mm. The base curve is the radius of the sphere that the back of the contact lens describes. Contact lenses must fit well to the wearer's cornea in order to be comfortable and to facilitate tear exchange and oxygen transmission.

In everyday practice, if contact lenses feel "loose" and slide easily a smaller base curve may work better. A large base curve may be needed if they feel tight. Lenses with smaller base curves are referred to as "steep".

Answer 5

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.