What is the name of the European system used for measuring lenses and frames from the center line?

The correct answer refers to the Dantum system, which is specifically designed for measuring lenses and frames with precision from the center line. This system provides opticians with the necessary tools to ensure accurate fitting of eyewear, focusing on critical aspects such as the alignment of the lenses relative to the center of the frame.

Using the Dantum system allows for consistent measurements that can enhance patient comfort and visual acuity, which is essential in the practice of opticianry. The Dantum system is distinct in its methodology compared to other measurement systems, emphasizing a unique approach tailored to the needs of eyewear fitting.

Other measurement options, such as the metric system, are broad measuring systems used for various applications but do not specifically pertain to optical measurements. The standard system typically refers to a more general framework that might not apply directly to the nuanced requirements of optics. The ISO system, while recognized internationally, is more associated with standardization across various industries rather than focusing specifically on optical measurements. Thus, the Dantum system is the correct reference for the specialized context of measuring lenses and frames in opticianry.