Nuclear sclerosis refers to cloudiness, hardening, and yellowing of the central region of the lens in the eye called the nucleus.

Nuclear sclerosis is very common in humans. It can also occur in dogs, cats, and horses. It usually develops in older people. These changes are part of the aging process of the eye.

If the sclerosis and clouding is severe enough, it's called a nuclear cataract. For vision affected by the cataract, the usual correction is surgery to remove the clouded lens and replace it with an artificial lens.

Age-related nuclear sclerosis alters the focus of the lens for near vision. Blurry near vision caused by age is also called presbyopia. Near vision is used for tasks like reading, working on a computer, or knitting. This can easily be corrected with a pair of reading glasses with the proper prescription to correct for the effect of the lens hardening.

In contrast, nuclear cataracts affect distance vision more than near vision. One effect of cataracts is that they can make driving more difficult. If you have nuclear cataracts, you may have the following symptoms:

  • difficulty seeing street signs, cars, the road, and pedestrians while driving
  • objects appearing blurry and colors faded
  • difficulty seeing things in bright light
  • experiencing more severe glare from headlights at night

Your vision may also seem dull or blurry, or occasionally you may have double vision.

The material that forms the lens of the eye is composed of proteins and water. The fibers of lens material are arranged in a very orderly pattern, which allows light to pass through.

As we age, new fibers form around the edges of the lens. This pushes the older lens material toward the center of the lens, causing the center to be denser and cloudier. The lens may also take on a yellowish color.

If the nuclear sclerosis is severe enough, it’s called a nuclear cataract. The proteins in the lens start to clump, scattering light instead of allowing it to pass through. Cataracts cause about half of all blindness in the world, and nuclear cataracts are the most common type.

Cataracts can be a normal part of aging, but they can also occur earlier due to exposure to UV light, smoking, and steroid use. Diabetes is also a risk factor for cataracts.

Age-related changes like nuclear sclerosis don’t require drugs or surgery. The lens hardening can impair near vision, but this can be corrected with reading glasses. If the hardening of the lens progresses to cataracts, replacing the lenses through surgery is generally safe and reverses vision loss.

As you get older, it's important to have regular comprehensive eye exams to catch conditions like nuclear sclerosis and cataracts early. If you notice changes in your vision, especially sudden changes, have an eye exam.

The American Academy of Ophthalmology recommends that you get a baseline eye examination at age 40 or sooner if you are at higher risk because of:

People 65 and older who are at average risk for eye conditions should be checked every 1 to 2 years, as recommended by your doctor. Comprehensive eye exams take 45 to 90 minutes and are usually covered by medical insurance.

Also important in helping to slow down lens changes is to wear sunglasses and avoid smoking.