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Base curve radius (BCR) or simply base curve (BC) is the measure of an important parameter of a lens in optometry. On a spectacle lens, it is the flatter curvature of the front surface. On a contact lens it is the curvature of the back surface and is sometimes referred to as the back central optic radius (BCOR). Typical values for a contact ...
Thus the base curve defines the front surface of the main part of the lens while the back surface geometry is changed to achieve the desired distance power. The "bifocal" is a third spherical segment, called an add segment , found on the front surface of the lens.
Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, [ 1 ] and they can be worn to correct vision or for cosmetic or therapeutic reasons. [ 2 ]
Base curve: BOZD Back optic zone diameter BOZR Back optic zone radius BVP Back vertex power CLAPC/CLIPC Contact-lens-associated/induced papillary conjunctivitis CLARE Contact-lens-associated red eye CLPU Contact-lens-associated peripheral ulcer Dk Unit of permeability DW Daily wear EW Extended wear FOZD Front optic zone diameter FVP
The optical magnification properties of spectacle lenses can be adjusted by changing parameters like the base curve, vertex distance, and center thickness. Magnification size matched lenses that are used to correct aniseikonia are known as iseikonic lenses. [3] Contact lenses may also provide less difference in retinal image size. [4]
P = front base curve (in 1/metres); h = vertex distance (in metres); F = back vertex power (in 1/metres), (essentially, the prescription for the lens, quoted in diopters). If the difference between the eyes is up to 3 diopters, iseikonic lenses can compensate.
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Radius of curvature sign convention for optical design. Radius of curvature (ROC) has specific meaning and sign convention in optical design.A spherical lens or mirror surface has a center of curvature located either along or decentered from the system local optical axis.