Optical activity of lysozyme in solution at 532 nm via signal-reversing cavity ring-down polarimetry

•Signal-reversing cavity ring-down polarimetry gives optical rotation precision of 100 microdegrees/pass.•Optical activity measured for lysozyme solution at 532 nm is 68.1 deg/dm/(g/ml).•Dry eye can be diagnosed measuring lysozyme in tears with polarimetry.