Power Methods

Calculates the back vertex power. Inputs are front surface power, back surface power, lens thickness in millimeters and refractive index.

Calculates the compensated lens power to be ordered. Inputs are the original power and vertex CHANGE in millimeters.

NOTE: The vertex change should be positive if the lens moves closer to the eye and negative if moved further away.

Calculates the dioptric power of a lens. Input is focal length in meters.

Calculates effective lens power. Inputs are original lens power in diopters and vertex CHANGE in millimeters.

NOTE: The vertex change should be positive if the lens moves closer to the eye and negative if moved further away.

Calculates the focal length of a lens. Input is dioptric power.

Calculates the front vertex power. Inputs are front surface power, back surface power, lens thickness in meters and refractive index

Calculates the nominal power of lens in diopters. Input is the index of refraction and radius of curvature for front/back surfaces in meters.

NOTE: You must enter the radius of curvature as plus or minus depending on the surface.

Calculates the nominal back surface power of a lens. Inputs are the front surface power and the total lens power.

Calculates the nominal power of a lens in diopters. Input is the dioptric power of the front and back of a lens.

Calculates approximate lens power in the 180 degree meridian.

Calculates approximate lens power in the 90 degree meridian.

Calculates the radius of curvature of a lens. Input is refractive index and dioptric power.

Calculates the spherical equivalent of a spherocylinder lens. Inputs are sphere and cylinder power.

Calculates the surface power of lens. Input is the refractive index and radius of curvature in millimeters.

Calculates the vergence of light at a given distance. Input is distance in Centimeters.

Approximates the overall change in lens power per mm. Inputs are original lens power and change in vertex.

NOTE: This approximation only gives the CHANGE in power and not the final power to be ordered from the lab. You must determine if the value should be added or subtracted from the original lens power.