WATER-CONTENT, LENS HARDNESS AND CATARACT APPEARANCE

Hardening of a cataractous lens is associated with the clinical appear ance of brunescene aNd advancing age. Alterations in the nature and co ncentration of proteins, lens fibre compaction and other biochemical c hanges may all be contributing factors towards increased hardness. As the nucleus confers most of the rigidity to the lens and water content decreases towards the centre of the nucleus, the hardness might be th ought to be related to total water content. To study the relationship between water content, hardness and the clinical appearance of catarac t, 135 lenses were obtained from eyes undergoing extracapsular catarac t surgery. The cataracts were assessed and classified pre-operatively. Lens hardness was determined by a specially designed guillotine and w ater content was measured by weighing the lens before and after desicc ation. A regression analysis was carried out to look at the variation of lens water content with hardness, degree of nuclear sclerosis, exte nt of cortical and posterior subcapsular cataract, vacuolation and age . Multivariate analysis of data demonstrated a relationship between le ns hardness and lens water content, degree of nuclear sclerosis and ag e (R2 = 0.59). An association could not be detected between lens water content and age, degree of nuclear sclerosis, extent of cortical and posterior subcapsular cataract and vacuoles. This study suggests that hardening of the lens is reflected by a respective decrease in water c ontent. Increased hardness is associated with coloration and advancing age.