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.
MEASUREMENT OF PHYSICAL QUANTITIES USING APPROPRIATE INSTRUMENTS. Mass is a measure of how heavy something is i.e., it is the amount of matter present in it. It can Be determined in the laboratory by using analytical or electrical balances as shown in Figs.2.1, 2.2 and 2.3. â¢ Mass is measured in grams (g), kilograms (kg) and tonnes.