Any good dog owner will do anything and everything they can to preserve their dogs eyesight, especially when their dog reaches old age and becomes more vulnerable to various sight-depriving conditions such as cataracts. Many good dog owners will also immediately panic and take their dog to the vet when if they spot the slightest amount of cloudiness in their dog's eyes -- however, in many cases this clouding is not caused by true cataracts, but by a much less serious form of occlusion known as nuclear or lenticular sclerosis.
What is nuclear sclerosis?
The lens of a dog's eye is made up of countless transparent fibres, which are reproduced constantly over the dog's lifetime. As a dog gets older, this constant cell multiplication causes some of the lens fibres to become compressed as they are more tightly packed against one another -- this affects the way they reflect and refract light, and causes them to lose some of their transparency. This, in turn, causes the pupil of the dog's eye to take on a cloudy appearance. This cloudiness generally looks grey or blue under natural light conditions.
It is not a certainty that your dog will develop nuclear sclerosis in later life, but it occurs so frequently that it is generally considered a normal part of a dog's aging process. The good news is that nuclear sclerosis very rarely causes appreciable blindness in dogs, unlike more serious cataracts. In more advanced stages of the condition, your dog may lose some of their visual acuity, but even in these later stages the dog almost always retains enough of its eyesight to go about their daily lift without issues. Nuclear sclerosis is also not a painful condition, and your dog may not even notice that anything is untoward with their vision.
How can I tell the difference between nuclear sclerosis and true cataracts?
If you spot cloudiness in your dog's eye and are worried about developing cataracts, try to determine the location of the cloudiness within the eyeball. While cataracts can occur within various parts of the eye, nuclear sclerosis only occurs within the eye, towards the pupil at its centre. As such, if you spot cloudiness on the outside edge of the dog's eye (the cornea), your dog may be developing a cataract and should be taken to the vet immediately for diagnosis and treatment.
As you can imagine, this can be difficult to accomplish without proper medical training, so do not hesitate to take your dog for veterinary treatment if you spot any cloudiness in the eye that you aren't 100% certain isn't a cataract. In the vast majority of cases, a vet can determine the source of the cloudiness with a simple, non-invasive examination using a lamp. However in some cases the vet will have to make a more involved examination using an opthalmoscope pressed against your dog's eye. This process is not painful, but your dog may require a simple administration of medicated eye drops to stop their pupil from automatically constricting.
How can nuclear sclerosis be treated?
If your dog is diagnosed with nuclear sclerosis, you may be disheartened to learn that there is no cure for this condition -- the good news is that the condition is easily managed, and should not progress to a point where it severely affects your dog's vision over the course of his or her natural lifespan. Keeping your dog as healthy as possible in old age is by far the best way to manage this condition. In particular, you should keep an eye on their weight, and do your best to keep your dog active and mentally stimulated for the rest of his or her life.