Nuclear Sclerosis

a normal aging process of the lens

What is it?
Nuclear sclerosis is a normal aging process of the lens.  The lens within the eye slowly lays down lens fibers in layers at its outer edge throughout life.  If you were to take a lens out of an eye and cut it in half it would look like an onion.  Since the eye is limited in size, the lens can only get so large.  In dogs, at about 6 years of age (in people this occurs at about 45 years of age) the lens is as large as it can reasonably be.  Once the lens has reached its maximum size, lens fiber layers become compressed toward the center making the lens harder and more optically dense.  As the lens becomes increasingly dense, it traps more blue light giving the impression of a pathologic cataract.  Without proper instruments it can be difficult to diagnose nuclear sclerosis from a cataract that will progress to vision loss.

What are the symptoms?
Nuclear sclerosis does not cause blindness.  Nuclear sclerosis may tend to limit animals’ near visual fields similar to what happens in humans when bifocals are required.  Clinically, dogs do not seem to have the same problems with near vision as humans because their eye is not designed for critical vision (reading, watching TV, etc.).

What is the treatment?
Nuclear sclerosis does not need to be treated. Nuclear sclerosis is a normal aging process and will not clinically affect vision in most animals.  Dense nuclear sclerosis is actually a testament to good care on the part of an owner since it signifies the animal has lived long enough to be affected by age-related processes.

Often it is not required but it may be a good idea to have the animal’s eyes checked annually since true cataracts can form in older animals and these can lead to vision loss.