Nuclear, or lenticular, sclerosis is a cloudiness of the lens seen in older animals.
New lens fibers are made in the periphery of the lens throughout life. As the lens ages, the fibers from the outermost portion are pushed inward by the newly formed fibers. This causes the inner portion of the lens to become denser and the appearance more cloudy. The normal arrangement of the fibers is not disrupted (unlike a cataract), so vision is not usually impaired. In geriatric animals, nuclear sclerosis can contribute to age-related decline in vision.
A bluish haze can be seen in the central portion of the lens with clarity remaining at the periphery, which is best visualized when looking at the eyes in dim light conditions or when the pupils are otherwise dilated. No significant changes in vision are caused by this condition, which differentiates nuclear sclerosis from diffuse cataract.
Nuclear sclerosis is a normal aging change. It is an expected finding in dogs older than 6 years of age and cats older than 8 years of age.
It is possible to pass light through nuclear sclerosis, allowing reflection from the shiny lining of the back of the eye ("tapetum") and also allowing visualization of the retina well on fundic examination.
No treatment is needed for this condition, as it is a normal aging process.