A lensmeter (“Lensometer”, “Focimeter”, “Vertometer”) measures the:
To use the lensmeter:
First adjust the power (dioptric) and axis dials until the thin line mires are straight and in focus. This is the spherical power. If the thick line mires are still out of focus, adjust the power (dioptric) dial until they come into focus to determine the cylinder (see text).
Bifocal add = Front vertex power of near – Front vertex power of distance.
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