What Amount of Prism Thinning Will Be in These Lenses?

January 27, 2016

Years ago, we took ⅔ of the ADD power to determine the amount of prism thinning we would manufacture into the lenses. For example: if we had an Add power of +2.00, then we would use 1 ⅓D of base down prism O.U. (At that time we only added prism thinning to Plus lenses.)


Today our computer programs figure the Optimal Prism Thinning by taking into account many more factors which have improved the cosmetics from the old ⅔ Add power system. We also apply the thinning to both Plus and Minus lenses. To explain all the calculations in the program would be way above my pay grade but I can tell you how it works. The program looks at each lens separately. It analyzes the distance power, ADD power, fitting height, edge style, frame size and shape then calculates the amount of prism thinning that would cosmetically look the best. It also considers the prism amount that an average patient can accept without causing visual problems. With the two prisms calculated it determines a single amount of prism thinning that would work best for the pair of lenses.


So how much prism thinning will be in these lenses? Well, give us a call. We will enter your parameters into our computer and report what the program determines the Optimal Prism Thinning is for that Rx.



Robert Hughbanks ABOC, HOAA- Manager of Training and Development