The authors have tested two formulas by means of which the filtrated and the intraocularly (intra-therally) synthesized fraction of particular protein can be distinguished. The laser nephelo-metric method was applied to determine the serum (IgG, IgA, IgM, C3, albumin), aqueous humor (IgA, IgM, albumin) and CSF (IgG, IgM, C3, albumin) protein values in 42 subjects to test two models in physiological conditions. It was confirmed that the best results were achived using the formula afterŠtambuk. Computer simulation performed to compare the formulas afterŠtambuk and Reiber&Felgenhauer showed a strong correlation (r>0.98) between the calculated filtrated fractions of both models in a wide range of different barrier permeabilities. Laser nephelometry proved to be a useful method to determine low IgA and IgM values in aqueous humor.