Certified Ophthalmic Technician (COT) Practice Test 2025 - Free COT Practice Questions and Study Guide

High power lenses are more likely to show a small error in power when measured on a lensometer due to their increased sensitivity to measurement variations. These lenses typically have a stronger curvature and a steeper slope, making them more prone to slight inaccuracies in their power readings.

When using a lensometer, the instrument relies on the alignment of the lens with the optical axis and the focal point. In high power lenses, even minor misalignments or small measurement errors can lead to significant deviations in power. This sensitivity is not as pronounced in low power or standard lenses, where the effect of such errors is minimized due to their flatter curvatures and lower optical effects.

Progressive lenses also have complex designs that incorporate multiple prescription zones, which can also complicate measurements, but it is the high power lenses that typically exhibit the most pronounced errors due to their optical properties. Thus, the characteristics inherent to high power lenses explain their greater likelihood of showing small errors when measured on a lensometer.