American Board of Opticianry (ABO) Practice Test

Where is the center point where lines that bisect the horizontal and vertical measurements of the lens in the boxing system intersect?

1. Provides approximately 43 diopters of power to an eye's refractive system

2. Geometric center

3. 20 feet

4. On the temporal side of the lens

The correct answer is: Geometric center

In the boxing system for lenses, the geometric center is the point where the lines that bisect the horizontal and vertical measurements of the lens intersect. This means that the lens is divided equally into four sections, with the geometric center being the exact center point of the lens. This is important for determining the optical center of the lens for proper fitting and prescription measurements. Options A, C, and D are incorrect as they do not pertain to the geometric center or the optical properties of lenses. Option A is referring to diopters, a unit of measurement used in optics but not relevant to the question. Option C is a measurement of distance, not relevant to the shape or properties of a lens. Option D is referring to the location on the lens, not relevant to the geometric center.