American Board of Opticianry (ABO) Practice Test

Which of the following is NOT a function of a lensometer in opticianry?

1. Reads base curves

2. Measures prism

3. Checks lens power

4. Checks lens thickness

The correct answer is: Reads base curves

A lensometer is an essential tool in opticianry that measures different properties of eyeglasses lenses, such as lens power, prism, and lens thickness. It allows opticians to accurately fit lenses into frames and ensure proper visual correction for patients. However, reading base curves is not a function of a lensometer. Base curves refer to the curve of the lens surface, which is usually measured during the manufacturing process and not during lens fitting. Therefore, A is the correct answer. B, C, and D are all important functions of a lensometer and are relevant to the lens fitting process. B measures the amount of prism in the lens, C checks the lens power to ensure it matches the prescription, and D checks the lens thickness to ensure it will fit properly into the chosen frame.