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.
http://www.scienceforce.org/ Â© 2006 Science Expeditionary Force Mass and weight are two different ways to measure matter. Mass is a measure of the amount of matter (âstuffâ) in an object. Mass does not change. Weight is dependent on location and can vary depending on where it is measured.