The topographic distribution of enzyme activities in normal rat lenses and their changes occurring during naphthalene cataract development were investigated. Cataract formation was documented by slit images according to the Scheimpflug principle. Before the onset of visible changes and after the development of early visible opacities, the animals were sacrificed, their lenses removed and biochemically analyzed. The lenses were divided reproducibly into 6 parts – the equatorial ring and 5 layers of central cylinders from the anterior to the posterior cortex. The enzyme activity spectra (AR, SDH, GR, GPX, PFK, ALD, GAP-DH, and LDH) showed region-related patterns, which could not be detected with analysis of the total lens. Image analysis of the first signs of opacity showed that changes in the activities of several enzymes correlate with density changes in the corresponding lens layers.