The significance of brown coloration with regard to lens nuclear hardness in the case of extracapsular lens extraction.

Prior to extracapsular cataract extraction, it is useful to have an indication of the nuclear hardness by means of slit-lamp microscopy. Using a fine conical probe and a miniature dynamometer, the resistance to penetration (hardness) of different colored lenses and different forms of 'senile' cataract was measured exactly. In cataracts with gray, brown, or black nucleus and sometimes a clear cortex or deep supranuclear, subcapsular or intumescent cortical opacities, distinct hardening of the nucleus was found, which reached values 3-4 times higher than in clear lenses of 80 year olds. Increasing pathological brown or black coloration of the lens nucleus is related to maximum hardness; on the other hand, maximum hardening was not restricted to brown or black coloration. In some cases we only found brownish or grayish coloration in the lens nucleus that had reached maximum hardness. We found the consistency of clear nuclei of deep supranuclear and subcapsular cortical cataracts to be the same values as those of clear lenses with clear nuclei of the same age.