What measurement indicates the strength of a lens?

The strength of a lens is indicated by its refractive power, which is measured in diopters. This measurement reflects the lens's ability to bend light rays and alter their path. A higher diopter value corresponds to a stronger lens that can focus light at a closer distance, making it crucial for prescribing corrective lenses to accommodate an individual's visual needs.

While the diameter of the lens, curvature of the lens profile, and thickness at the center are important attributes that can affect the optical performance and fitting of eyeglasses, they do not directly convey the strength of the lens. The diameter may influence the overall appearance and fitting of the glasses, the curvature affects the way light is focused but does not quantify refractive power alone, and the thickness can impact weight and aesthetics rather than lens strength. Ultimately, the diopter measurement is the standard metric used in optics to describe how much a lens can converge or diverge light, which is essential for effective vision correction.