1, refractive index (n);
2. Water content (% by weight);
3, oxygen permeability (cm2 / s) (mlO2 / ml · kPa) @ 25 ° C × 10-11;
4. Elastic modulus Pa*104;
5. Specific gravity (g/cm3) ;
Refers to the clarity of a substance. It is a combination of chemical, purity and hydration of materials and other factors. The transparency of a substance is usually expressed as a percentage of the transmittance of a substance sample with a specific wavelength of light. This value is between 92% and 98% in most clear contact lens materials (no coloring).
Hardness and toughness
The hardness of the material is an important quality indicator that reflects the manufacture of the lens and the durability of the lens. Hardness is a property that hard mirrors are more closely related than soft mirrors. Toughness reflects the degree of flexibility of the material. A flexible material makes the lens feel good for the initial stage, but it cannot correct the corneal astigmatism because it is easy to adhere to the cornea and conforms to the shape of the cornea.
Indicates the maximum tensile force the material can withstand before it is fractured. High tensile strength → good durability.
Represents the ability of a material to remain in shape when subjected to pressure.
Low material → low resistance to pressure.
High material → better resistance to stress. Maintain shape and provide better vision.