Understanding Prism Thinning

The curvature of a progressive addition lens surface gradually increases toward the bottom of the lens, becoming increasingly steeper. This increase in curvature (and surface power) is what produces the add power of the progressive lens. Unfortunately, because the...

Methods for Estimating Lens Thickness

Often, it is beneficial for the eye care professional to predict the finished thickness of a pair of spectacle lenses. Determining the change in thickness that results from the patient's use of a different frame or lens style is a common example.Patients investing a...