Non-invasive optical measurement of glucose and other dissolved substances in human or animal intraocular fluid. A method takes advantage of the fact that the wave dependence of optical activity is fundamentally different from corneal birefringence. The optical activity of substances dissolved in the intraocular fluid, such as glucose, lactate, ascorbic acid or amino acids, is scaled as a first approximation with the reciprocal value of the wavelength square. In contrast, corneal birefringence is scaled with the reciprocal value of the wavelength and therefore behaves considerably different from the optical activity. For the method according to the invention, a physical model is used, which describes the influence on the polarization of measurement radiation by the components of the eye, particularly by the intraocular fluid and the cornea.