In people with keratoconus, rigid contact lenses improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the lens, thereby creating the effect of a smoother cornea.
Rockwell Hardness Testing Hardness is a characteristic of a material, not a fundamental physical property. It is defined as the resistance to indentation, and it is determined by measuring the permanent depth of the indentation.lick here to learn more about hardness testing basics. The Rockwell hardness test method, as defined in ASTM E-18, is the most commonly used hardness test method.
The principal purpose of the hardness test is to determine the suitability of. a material for a given application, or the particular treatment to which the. material has been subjected. The ease with which the hardness test can be. made has made it the most common method of inspection for metals and al-. loys.