As animals age, just as for people, there are normal changes that occur. By far the most common of these is a condition called nuclear sclerosis.
You may have noticed that, as your pet ages, the normally dark pupil starts to look cloudy. This may be more obvious in low light when the pupil is larger and more of the cloudy lens is visible.
The lens is made up of layers of cells arranged somewhat like the layers of an onion. As animals (and us!) get older, the cells become packed together more tightly as new layers are added to the outer lens surface. The increased density of the lens causes it to look cloudy in dogs over about 7 years of age and the lens will continue to appear cloudier over time. Nuclear Sclerosis is easily mistaken for a cataract, a different problem that also causes the lens to become cloudy. While a cataract is an abnormality that can cause blindness and inflammation inside the eye, nuclear sclerosis is normal for an older dog, and the condition has minimal effect on vision.
Just as for middle-aged people who need reading glasses, a dog with nuclear sclerosis will not be able to see well up close. Going down stairs and catching a small treat may be more difficult, but they will still see that rabbit or football in the distance.
This and some other age-related changes in the eye are normal, very slowly progressive and should never cause significant problems. If you notice a major change in your dog’s vision, please give us a call.
-Mark Taylor MRCVS
