As pets age, changes occur within their bodies, including the eye. The lens of the eye is responsible for directing and focusing light onto the retina in the back of the eye. This light is then detected and results in vision.

The lens is encased in a membranous capsule. The lens is a continuously changing structure, with new layers being laid down on top of one another throughout the life of the animal. Because the eye is fixed in size and the lens capsule does not stretch a great deal, the lens cannot get larger as these new layers develop. Instead, the inner layers of the retina become compressed, which allows room for the new layers to be laid down. The oldest layers of the lens are in the center of the lens, and this area is called the nucleus. The newest layers of the lens surround the nucleus and this outer area is called the cortex.

As the animal ages the nucleus of the lens becomes denser, harder and somewhat cloudy in appearance. The nucleus may have a blue-gray tint to it, while the cortex remains completely clear and transparent. This aging change of the lens is known as lenticular or nuclear sclerosis. Typically, signs of lenticular sclerosis begin around 6 to 8 year of age in the dog and slowly become more obvious as the dog ages.

In the geriatric dog, lenticular sclerosis can be so cloudy that the condition is easily mistaken for a cataract of the lens. Cataracts can also result in a gray-white appearance to the eye due to cloudiness within the lens. Fortunately, vision is not significantly affected in lenticular sclerosis until the last stages of the dog's life.

What to Watch For

As the animal ages the pupils will lose their jet black color and will become mildly bluish white or gray.

Vision usually remains normal until the animal is quite old.

If the animal lives long enough, then mild changes in vision may become apparent, such as not being able to distinguish between individual people at a distance, and acting as if a person is not recognized until they get quite close to the animal.

More significant changes in vision may indicate the presence of aging or degenerative changes in other structures of the eye, such as the retina.

Diagnosis

Lenticular sclerosis can be diagnosed by a veterinarian on an eye examination. Dilation of the pupil is often necessary to distinguish this condition from a cataract of the lens.

Your veterinarian may refer your cat to a veterinary ophthalmologist for further evaluation using specialized instrumentation, such as slit lamp biomicroscopy.

It is important also to assess other structures in the eye for aging or degenerative changes.

Treatment

There is no treatment required for lenticular sclerosis. The condition does not bother the interior of the eye and does not often affect vision until the animal is quite aged.

By the time vision is affected in older animals, other degenerative changes are often contributing, such as senile retinal degeneration.

It is important to differentiate lenticular sclerosis from cataracts because cataracts are often treated by surgical removal of the lens.

Home Care and Prevention

As the animal ages it is important to try and keep the environment consistent and predictable. Leave furniture in the same place, make sure that toys are not left in their path, keep stairs and decks cordoned off, and supervise the animal closely when outside.

As animals age they may also develop a significant decrease in their senses of hearing and smell. This can make it difficult for them to adjust to new environments, and they can become lost and confused.

There is no prevention for this condition. Every animal develops lenticular sclerosis to some degree as they get older.