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: how much matter is in an object. We measure mass by weighing, but Weight and Mass are not really the same thing. These are the most common measurements: 1  Grams.2  Kilograms. 3  Tonnes. gram is about: 1  a quarter of a teaspoon of sugar. 2  a cubic centimeter of water. 3  a paperclip. 4  a pen cap. 5  a thumbtack. 6  a pinch of salt. 7  a piece of gum. 8  the weight of any US bill. 9  0.035274 of an ounce to 6 decimal places (we need 28.349523 grams to make an ounce). 10  one fifth of a piece of paper (80 gsm A4 paper weighs 4.8 g).