What is the prismatic effect 2 mm from the optical center of a +7.00 lens?

To determine the prismatic effect created by a lens at a specified distance from its optical center, one can use the following formula:

Prism diopters (PD) = (deviation in mm) / (distance in meters).

In this case, a +7.00 D lens introduces a prismatic effect. The conversion factor for prism diopters is that for every diopter of lens power, there is a deviation of 1 mm for every 1 meter from the optical center.

For a +7.00 D lens and a distance of 2 mm (which is 0.002 meters) from the optical center, we can calculate the effect as follows:

1. Multiply the lens power (+7.00 D) by the induced deviation (2 mm):

+7.00 D x 2 mm = 14 pd (prism diopters).

2. Since we calculate in meters for the conversion:

14 pd / 1 = 14 prism diopters when distance is accounted.

However, the actual correct calculation for 2 mm translates into measuring it the proper way, hence we can leverage the rule of thumb that for every D lens power at 1 mm deviation at the corresponding distance can lead us to