Archive for the “Problem Solving” Category

Compensated and Effective Power

Posted on November 11th, 2009 by Brent McCardle

When we compensate an Rx, we do so because the lens changes power as moves closer or farther away from the eye. We are making an Rx stronger or weaker depending on whether the lens is moved closer farther away.

Oblique Meridian

Posted on November 10th, 2009 by Brent McCardle

1. The approximate power on the vertical meridian for the Rx +3.00 -1.50 x 102 is ______. Give the power rounded to two decimal places, not to 1/8 diopter steps.

Back Vertex Power

Posted on November 10th, 2009 by Brent McCardle

1. If a polycarbonate lens (n = 1.586) is made with a front surface power of +10.25, a back surface power of -3.00, and a center thickness of 4 mm, what power will the lensmeter show? Give the power rounded to two decimal places, not to 1/8 diopter steps.