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 matter in an object weight is a measure of the gravitational force exerted on an object gravity is a force of attraction between objects that is due to their masses, which decreases as the distance between the objects increases.ravity is the attraction between two or more masses. so any object always has mass. if the object is near something like a planet gravity effects it. which gives a fore on it, called weight.