FIELD: medicine.SUBSTANCE: group of inventions refers to medicine. A device according to the first version comprises a cylindrical body and a piston rod. The cylindrical body has a longitudinal axis and a canal along the longitudinal axis. The piston rod is provided inside and can travel along the canal in the cylindrical body within the working range. The cylindrical body and piston rod can be functionally coupled by friction to generate various frictional forces by the piston rod travel within the working range to balance one or more changes in travelling resistance observed when a lens is inserted in the eye. The functional coupling by friction comprises a slot extended longitudinally along the cylindrical body and having a variable width, and a projection perpendicularly extended from the piston rod and coupled by friction with slot side walls when the piston rod travels within the working range. A device according to the second version comprises the cylindrical body and the piston rod. The cylindrical body has the longitudinal axis and the canal along the longitudinal axis. The piston rod is provided inside and can travel along the canal in the cylindrical body within the working range. The cylindrical body and piston rod can be functionally coupled by friction to generate various frictional forces by the piston rod travel within the working range to balance one or more changes in travelling resistance observed when the lens is inserted in the eye. The functional coupling by friction comprises an outlet integrated with the cylindrical body or rigidly coupled therewith, and a contoured surface of the piston rod which is coupled by friction with the outlet when the piston rod travels within the working range The contoured surface comprises a textured surface having a texture varied throughout at least a portion of the piston rod length.EFFECT: inventions provide reducing or eliminating the resistance force variations making the IOL introduction more uniform, pred
