Abstract: Method and apparatus are disclosed for measuring contaminants in aqueous humor without rupturing an examined eye. The apparatus includes a laser which projects a light beam through a gonioscopic lens into the aqueous humor of the examined eye. The light is scattered in the humor with a portion of the scattered light being reflected by the gonioscopic lens to an analyzing system. The system measures the diffusion constant of any contaminant in the aqueous humor and, by comparing the diffusion constant to a set of known diffusion constants, determines the composition of the macromolecules or the cells of the contaminant.