Scleral lenses have gained popularity in the last decade. From a lens with limited viability for over 100 years to the fastest growing segment of the gas permeable lens market, scleral lenses have come a long way.
Mass and Weight. The mass of an object is a fundamental property of the object; a numerical measure of its inertia; a fundamental measure of the amount of matter in the object. Definitions of mass often seem circular because it is such a fundamental quantity that it is hard to define in terms of something else.
Mass is the amount of stuff in an object. That is, the amount of atoms and molecules present. Mass in science, is measured in the metric system using units such as kilogram (about 2.2 pounds)nwhich are a thousand grams, grams, centigrams (hundredths of grams), and milligrams (thousandths of grams). Mass is different from weight, Weight is a force.