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.
Hardness is a measure of how difficult or easy it is for a substance to be penetrated or scratched! For example, steel (like a steel nail) can scratch your fingernail, so steel is harder than fingernail!!. That's what I thought! But the question is: how can you describe the amount of hardness!. Some question!