Polarization lens with adjustable focal length

The utility model relates to the technical field of medical instruments. The focal length-adjustable polarizing lens comprises a base, a lens assembly and a polarized light source assembly, the lens assembly is connected with the base, the polarized light source assembly is arranged above the lens assembly, and the polarized light source assembly can filter light reflected by grease on the surfaceof skin, so that an image obtained by the lens is clearer; the lens assembly comprises a first knob ring sleeve, a sliding block and a lens arranged on the sliding block; the first knob ring sleeve is adjusted by rotating; the bulge on the peripheral wall of the sliding block is driven to move along the threaded groove in the inner wall of the first knob ring sleeve; a lens on the sliding block is driven to move along a threaded groove in the inner wall of the first knob ring sleeve; the distance between the lens on the sliding block and the skin is adjusted, the output multiple of the lens is changed, a clear imagin