Nuclear sclerosis is an age-related change in the density of the crystalline lens nucleus that occurs in all older animals.[1] It is caused by compression of older lens fibers in the nucleus by new fiber formation. The denser construction of the nucleus causes it to scatter light. Although nuclear sclerosis may describe a type of early cataract in human medicine,[2] in veterinary medicine the term is also known as lenticular sclerosis and describes a bluish-grey haziness at the nucleus that usually does not affect vision, except for unusually dense cases.