Age-related cataract Age-related nuclear cataract 2011-06-27T09:49:20Z HP:0011142 As the lens ages, new layers of fibers are added and the lens nucleus is compressed and becomes harder (nuclear sclerosis cataract), with associated yellowing of the lens. Nuclear sclerosis typically progresses slowly. UMLS:C1832423 A type of age-related cataract that primarily affects the nucleus of the lens.