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. 1  Mass is a measure of the amount of matter an object contains. - 2  The amount of mass in an object does not change. - 3  Gravitational force can change (i.e. the moon), which can cause weight to change. - 4  This is the reason scientists prefer to measure matter by its mass rather than its weight.