As dogs get older, they develop a condition of the eyes that’s called Nuclear Sclerosis. Nuclear Sclerosis is the hardening of the lens of the eye which makes it difficult for dogs to see. Senior dogs frequently have a bluish cloudiness at the center of their eyes. That is Nuclear Sclerosis at work and it can eventually make it very difficult, sometimes impossible, for dogs to see – especially in limited light such as dawn, dusk and at night. While there is no real treatment or cure for Nuclear Sclerosis, providing your dog with a source of bright light at his eye level, such as with a light up dog leash or dog collar, can help tremendously.