Freezable and non-freezable water content of cataractous human lenses.

Twenty-nine cataractous human lenses between the ages of 36 and 93 were investigated. The total water content of cortex and nucleus were obtained by vacuum dehydration. The freezable water content was measured by differential scanning calorimetry. The non-freezable water content was obtained by difference. To measure the extent that syneresis contributes to cataract formation, an excess function was designed. The excess function represents the changes that occur, for example, in non-freezable water content due to cataractogenesis. It is calculated as the difference between the non-freezable water content of a normal lens and that of a cataractous lens of the same age. On the average, there is 7% less non-freezable water in the cortex of a cataractous lens than in the cortex of a normal lens. The corresponding number for the nucleus is 9%. This represents 29 and 36% changes, respectively, in the cortex and nucleus due to syneresis during cataractogenesis.