American Board of Opticianry (ABO) Practice Test

What effect do increasing plus powers have on the base curves selected for the lens?

1. Decrease steepness

2. Increase steepness

3. No effect on steepness

4. Transform into prisms

The correct answer is: Increase steepness

When selecting a lens, one important consideration is the base curve, which determines the curvature of the lens. Plus powers refer to the amount of magnification in the lens. As the plus power increases, the lens will need more curvature to achieve the desired prescription strength. This means that the base curves selected for the lens will become steeper, and the lens itself will have a more pronounced curvature. Choices A and C are incorrect because increasing plus powers do not decrease or have no effect on the base curve steepness, respectively. Choice D is also incorrect because increasing plus powers do not transform into prisms, which are an entirely different type of lens.