A drip chamber (102, 202, 302) for an infusion tube, including: a first end (104, 204, 304) arranged to receive a drip tube (106, 206, 306)； a second end (108, 208, 308) including an exit port (110, 210)； at least one wall (112, 212, 312) connecting the first and second ends； a space (120, 220, 320) enclosed by the first and second ends and the at least one wall； and at least one lens (121, 221, 321) integral to the at least one wall or directly fixed to the at least one wall.
