Abby Norman is a freelance science writer and medical editor. She is also the author of "Ask Me About My Uterus: A Quest to Make Doctors Believe in Women's Pain (2018)."

Johnstone M. Kim, MD, is board-certified in ophthalmology. He's a practicing physician at Midwest Retina in Dublin, Ohio and previously served as a full-time faculty member at the Wayne State University School of Medicine and the Kresge Eye Institute in Detroit, Michigan.

Nuclear sclerosis is a primarily age-related eye condition in which the nucleus, or central part of the lens, hardens or gets cloudy.

Since this part of your eye receives light, nuclear sclerosis can greatly impact your vision. Lenses affected by nuclear sclerosis can also become noticeably cloudy or yellow.

The condition is called nuclear sclerotic (NS) cataracts when it progresses to the point that it's severe or causes symptoms.

This article reviews the symptoms of nuclear sclerosis and NS cataracts, causes and risk factors, and how they're diagnosed and treated.

Early on, symptoms of nuclear sclerosis can be subtle. It may take a long time for you to notice them.

Some people with nuclear sclerosis see a temporary improvement in their vision. This is sometimes called second sight. It can make you think your eyes have gotten better, but the slow decline inevitably continues.

A cataract is cloudiness in the lens of your eye that impairs your vision. Cataracts result from the breakdown of proteins. They prevent light from passing properly through the lens.

Eventually, as an NS cataract begins, you or someone close to you may notice a change in your eye's appearance (cloudiness, yellowing, browning). A healthcare provider may also discover it during a physical or eye exam.

At first, you may get a cataract in just one eye. Over time, you'll likely develop one in the other eye, too.

A nuclear sclerotic cataract can be classified as either immature or mature, depending on how severe the clouding is. In severe cases, untreated nuclear sclerotics cataracts can cause blindness.

Cataracts are the leading cause of blindness both in the United States and around the world.

In nuclear sclerotic cataracts, the center of the eye's lens becomes thick and discolored. This clouds your vision. Blurred vision, haloes around lights, and washed-out colors are common symptoms. Vision may improve, only to decline again. Severe cases can lead to blindness.

Nuclear sclerosis is caused by proteins in your lens that naturally break down over time. They clump together, in this case, causing hardening that impedes light from passing through the center of the lens to the retina.

The retina processes light and transfers signals that allow your brain to register images. Less light going through the center of the lens due to nuclear sclerosis means less "information" for the retina to translate. That, in turn, equates to vision issues.

As you age, your nuclear sclerosis will eventually develop into an NS cataract. In addition to aging, cataracts can be caused by trauma or disease.

Age-related cataracts are extremely common and nuclear sclerotic cataracts are the most common kind. Other types of cataracts result from changes to different parts of the lens.

To differentiate them from other types of cataracts, NS cataracts caused by age are sometimes referred to as nuclear senile cataracts.

Age is the main risk factor for nuclear sclerotic cataracts. Other risk factors include:

Aging is the most common cause of nuclear sclerotic cataracts, but some modifiable factors like smoking, heavy alcohol use, and exposure to UV light can increase your risk.

If you have symptoms that could point to nuclear sclerosis, see an eye doctor (ophthalmologist ).

Nuclear sclerotic cataracts are typically easy to diagnose. That's especially true if they've changed how the lens looks.

Healthcare providers use special eye drops to dilate (widen) your pupil. Then they look inside your eye with a handheld instrument called an ophthalmoscope and a slit-lamp microscope. If you have nuclear sclerosis, the healthcare provider will see abnormalities in the lens's nucleus.

They'll also perform refraction (vision prescription) and acuity (eye chart) tests on both eyes to check your vision's clarity and sharpness.

Sometimes an eye doctor can see early changes before you have noticeable symptoms. This reinforces the importance of routine eye exams. Early diagnosis means early treatment, and that may prevent or delay serious vision loss—including blindness.

Everyone with nuclear sclerotic cataracts has a different experience. Some people aren't bothered by them, while others' vision is severely affected. Treatment can help preserve your vision.

Treatments for nuclear sclerotic cataracts are the same as for all types of cataracts. You have several options, which you and your healthcare provider will consider depending on the severity of your condition and the extent to which it is impacting your life.

Early on, glasses or contacts may be all you need. You may also find it helpful to:

Eventually, healthcare providers may be able to treat nuclear sclerosis with eye drops. Treating it in the early stages may prevent NS cataracts from forming. For now, though, this treatment is experimental.

Healthcare providers generally suggest surgery when cataracts of any type significantly impact your life or make you unable to drive.

Cataract surgery involves removing the cloudy lens and replacing it with a clear synthetic one that is created especially for your eye. It is considered safe for most people.

If you have nuclear sclerotic cataracts in both eyes, they will probably be removed during separate procedures done about a week apart. Most people fully recover in about eight weeks.

An eye doctor can identify nuclear sclerosis with tests you should already be familiar with if you've had a routine eye exam. Glasses may be all you need in the beginning, but surgery to replace your lens may be recommended later on.

Nuclear sclerotic cataracts impact the center of your eye's lens. With age (or sometimes, eye disease), the lens thickens, becomes cloudy, and impairs your vision.

Symptoms include blurry vision (especially at night), frequent updates to your corrective lenses, and colors appearing less vivid.

Healthcare providers diagnose nuclear sclerosis with a dilated eye exam. Treatment includes corrective lenses or, later on, surgery to replace the affected lens.

With treatment, nuclear sclerosis and nuclear sclerotic cataracts rarely cause blindness. Getting regular eye exams is key to early diagnosis and treatment, which can help preserve your vision.

Remember that you may not notice growing nuclear sclerotic cataracts for years. As you get older, don't skip these exams and tell your healthcare provider about any vision changes.

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