An Overview of Nuclear Sclerosis

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Nuclear sclerosis is the clouding of the lens of the eye. Nuclear sclerotic cataracts become a problem when it becomes severe or symptomatic. All animals, including humans with a natural anatomic lens can develop nuclear cataracts and its related symptoms as they age.

nuclear sclerosis symptoms
Illustration by Emily Roberts, Verywell


When we're young and our eyesight is healthy and at its prime, the part of our eye that receives light (lens) is clear. The clarity of our eye's lens is important for seeing clearly. With age or due to diseases affecting the eye, the lenses may harden, change color, and become opaque or "cloudy." This distinct appearance isn't just a sign of getting older, it can also impair vision.

When the central part of the lens (nucleus) hardens, yellows, or appears cloudy, this is sometimes called nuclear sclerosis. If the condition becomes severe, it leads to the development of nuclear sclerotic cataracts. The type of cataract a person has, and what it's referred to as, will depend on which part of the lens changes.

Depending on how severe the clouding is, the cataracts may be "immature" or "mature." When a cataract is mature, the lens will appear to be almost completely white.

When a person first starts developing cataracts, they may not notice any changes to their eyes or vision. Cataracts slowly and progressively worsen over time. The signs and symptoms may be subtle at first and can include:

  • Worsening vision (especially distance) that doesn't improve with glasses or contacts
  • Needing to frequently update a glasses or contact prescription
  • Vision that seems blurry, unfocused, or unclear
  • Colors and shadows appear different (less vivid)
  • "Haloes" or rings around light sources, or the sense that one is seeing a "glare"
  • Trouble seeing at night, especially when driving

Changes to the appearance of the eye may be noticed when looking in the mirror or at photographs. Sometimes these changes may be first noticed by a partner, family member, or friend. They may also be noted by a doctor at a routine physical or by an eye doctor (ophthalmologist) during an eye exam.

Cataracts of any type don't typically cause any discomfort or pain. Those symptoms may be indicative of other conditions and should be investigated thoroughly by a medical professional.


Humans have been dealing with cataracts since ancient times. As we get older, our bodies change in many ways, from our bones to our brains to our eyeballs. Each of our eyes has a see-through lens that allows light to reflect off the retina. The reaction of the light hitting the retina sends an electrical signal along the optic nerve to our brain, which tells us what our eyes are seeing.

As a person ages, it's common for the central part of the eye's lenses (nucleus) to thicken or harden (sclerosis), change color (yellowing), or become "clouded" in appearance. When cataracts become very severe, the lens of the eye will look gray or milky white. As the lens becomes more clouded, the amount of light that can pass through and reach the retina decreases and starts to affect vision.

Cataracts are very common. A person may develop a cataract in one eye (unilateral) at first, but as time goes on they are likely to develop one in the other eye, too (bilateral).

Nuclear sclerotic cataracts specifically happen when fibers near the central portion of the lens (nucleus) thicken with age. These fibers are mostly made of protein and water. As we age, the old fibers don't clear out of the way to make room for new fibers, and the crowding causes the "cloudy" or hardened lens.

Other types of cataracts result from age-related changes to different parts of the lens.

Developing cataracts is extremely common the older one gets. At some point, if a person lives long enough, it's almost certain they will develop at least a mild case. There are other factors that can increase a person's risk of developing cataracts of any type, and some may lead them to begin at a younger age.

Other Risk Factors

  • Smoking or tobacco use
  • Taking steroid medications
  • Trauma, injury, or other diseases of the eye
  • Prolonged and frequent exposure to UV light (sunlight) or radiation
  • Genetic conditions including galactosemia, Down syndrome, and myotonic dystrophy
  • Other health conditions including diabetes, herpes infection, syphilis, rubella, and others

Cataracts may also be present at birth (congenital) or develop at a young age due to conditions such as hyperthyroidism. A person is more likely to develop cataracts early if someone else in their family did, meaning there is likely a genetic factor.

In some cases, a person with nuclear sclerosis will experience a temporary improvement once their vision has started to decline. This is sometimes called "second sight." While it may make a person think their eye problems are resolved, if caused by age-related changes to the lens, the decline will continue, though the progression may be slow.


If a person is having symptoms related to nuclear sclerosis, such as blurry vision or needing to change their glasses prescription, they may make an appointment to go to the eye doctor (ophthalmologist). Eye doctors can use different types of tests and exams to diagnose diseases of the eye, including those that are related to age. They can test how well a person sees with and without glasses, measure the pressure in their eyes, observe how well the eyeballs move, and when (and how much) the pupils dilate.

Cataracts are typically quite easy to diagnose, especially if they are severe enough to have changed how the lens looks, giving it the characteristic "milky" appearance.

Even if a person has not started having any trouble with their vision, changes indicative of cataracts, (including nuclear sclerosis), may be noticed during routine checkups or exams with their primary care doctor or eye doctor.

Using an ophthalmoscope, an eye doctor can get a very good look at the lens of a person's eye and may be able to notice subtle changes occurring before the cataracts have progressed to the point where a person's vision has been severely affected. Catching these signs early can help a person learn about treatment options sooner and may prevent or delay more serious vision loss, including blindness, that cataracts can cause.

If a person has developed nuclear sclerosis, an eye doctor would notice changes only in the nucleus of the eye's lens. Involvement of this part of the lens is the most commonly seen.


If a person has cataracts, they may consider having surgery to remove their cloudy natural lens and replace it with an artificial clear lens to restore their sight.

When the condition is still mild or progressing very slowly, a person may not need surgery. They may need glasses or visual aids and will want to be sure to protect their eyes from UV rays by wearing sunglasses. A person with nuclear sclerosis may be prescribed eye drops for cataracts in the future, but this remains experimental at this time.

Every patient with cataracts will have a different experience. Some may not be very bothered by them at all, while others may practically lose their sight completely. If the cataracts become severe enough that a person can't see well or is no longer able to drive, their doctor will probably suggest surgery.

If a patient doesn't feel ready for surgery and their vision is not impaired, their doctor will likely advise them that it is fine to put off surgery. If a person does not have surgery for cataracts, the condition won't damage the eye in the long term. The main concern is that, over time as the cataracts become more severe, a person's vision is likely to be increasingly affected.

Sometimes, if a person has another health condition such as diabetes, their vision won't improve even with cataract surgery because there are other underlying reasons their vision is poor. In this case, working closely with doctors and specialists will be important to maintaining independence and good health as one gets older.

Cataract surgery is regarded as being safe and effective for most patients. During the procedure, an ophthalmologist removes the old, hardened, lens and replaces it with an artificial lens (intraocular lens) that has been designed specifically for a patient's eye.

If a person has cataracts in both eyes they would like removed, they will usually need to have one done at a time—usually the second can be done a week after the first, depending on your doctor's recommendation. A person may be instructed to wear an eye patch directly after surgery and at night for the first couple of weeks. A doctor might prescribe medications and tell a person to avoid straining or lifting heavy things. Most people need around eight weeks to fully recover after cataract surgery.

A Word From Verywell

Developing cataracts of any type is very common as a person ages; by the time most people reach their 80s, half will have developed cataracts in at least one eye that will be severe enough to warrant surgery. Every patient will experience cataracts differently and some may not want (or need) surgery to remove them. If vision is severely affected, surgery to remove the cataracts and replace them with artificial lenses may be required to restore a person's sight. Other patients will only have mild cataracts that can be treated with wearing protective eye gear (sunglasses) and using prescribed or over-the-counter eye drops.

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Article Sources
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