Vision, Optics and Refractive Correction

Flashcards related to sign conventions, Snell’s Law, lens power, lens measure, and thick lens calculations.

Back Vertex Power (BVP)

The power of a lens measured with respect to the back vertex; the reciprocal of the Back Vertex Focal Length.

Front Vertex Power (FVP)

The power of a lens measured with respect to the front vertex. The reciprocal of the Front Vertex Focal Length.

Lens measure

A device for measuring surface power; measures sag, determines radius of curvature from sag across a known chord, and then displays surface power using an assumed refractive index.

Refractive index (n)

Velocity of light in vacuum / Velocity of light in medium

Power (F) of a spherical refracting surface

F = (n’ – n)/r