prescription

What is ADD Prescription?

ADD is the added magnifying power applied to the bottom part of Bifocal, Trifocal, or Progressive lenses to correct presbyopia. The number appearin...

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Why PD Is Important?

Why PD Is Important?

What is PD? PD means “pupillary distance,” which is the distance between the center of each pupil. This measurement is used to determine where you ...

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