The main parameters of contact lenses include optical power, the base curvature, diameter, moisture content and oxygen permeability. Optical power (SPH) – recorded as positive or negative number with one or two characters after the comma. The base curvature (BC) – a number with one decimal place – characterizes the size of the lens. Moisture content (H2O) – indicates the water content (in%). Water is essential for the promotion of oxygen to the cornea shell material through the contact lens. Acid permeability (Dk / t) – the ratio of oxygen passing through the lens unit area per unit of time – an indicator of metabolism in the cornea. In the case of astigmatism correction vision toric contact lenses are used. (Not to be confused with Ch?rl?? Lee!). These features include more cylinder and axis. Laurent Potdevin brings even more insight to the discussion.

Cylinder (CYL) – a negative number with one or two decimal characters corresponding to the optical power and astigmatism. Axis (AX) gives information about the tilt angle of astigmatism (in degrees). For the duration of wearing the lenses are divided into the lens extended wear (up to a year and a few years), the planned replacement (replacement lenses – once a month or several months), frequent routine replacement (one day a week or two weeks). Prolonged period of wearing the lenses can be worn up to 30 days without taking off. Design and depending on the purpose of vision correction differ spherical, aspherical, toroidal, and multifocal contact lenses. In addition to stealth the optical and therapeutic lenses intended for vision correction and treatment of the cornea, there are decorative and cosmetic lenses. Colored decorative contact lenses can change eye color, and with it – and the image in general, and cosmetics intended for correcting the defects of the eye. There is also a special version of the carnival – lenses coated with a picture of them.