The lens of your eye is made mostly of water and proteins. These proteins are arranged in a very precise way that keeps the lens clear and allows light to pass through without interference. Over time, those proteins can begin to break down or clump together, creating cloudy patches in the lens. This is the basic process behind cataract formation.

Aging is the most well-known cause, and it happens because the natural systems that protect lens proteins become less effective over the years. Oxidative stress, which is damage caused by unstable molecules called free radicals, is one of the key drivers of this process. The lens has built-in defenses against this kind of damage, but those defenses can weaken with time and other contributing factors.

Beyond aging, several other things can contribute to cataract development:

• Ultraviolet (UV) light exposure from the sun over many years can accelerate changes in lens proteins.
• Smoking has been linked to a higher risk of certain types of cataracts.
• Diabetes can affect the chemistry inside the eye in ways that make the lens more prone to clouding.
• Eye injuries can damage the lens directly and lead to what is called a traumatic cataract.
• Certain medications, including long-term use of corticosteroids, can increase the risk of cataracts in some people.
• Radiation exposure, including radiation used in cancer treatment, can sometimes affect the lens.
• Congenital causes mean that some babies are born with cataracts or develop them in early childhood, often due to genetic factors or infections during pregnancy.

In many cases, cataracts develop from a combination of factors rather than a single cause. Understanding your personal risk factors is a helpful starting point for any conversation with an eye care provider.

Not all cataracts are the same. They can vary based on where they form in the lens, what caused them, and when they develop. Knowing the type of cataract can help explain specific symptoms and how the condition may progress.

Nuclear cataracts form in the center of the lens, in an area called the nucleus. This is the most common type associated with aging. As the nucleus becomes denser and cloudier, it may cause a gradual shift in how the eye focuses. Some people with early nuclear cataracts notice a temporary improvement in their close-up vision before their vision declines overall, a phenomenon sometimes called "second sight."

Cortical cataracts develop in the outer layers of the lens, known as the cortex, and often appear as wedge-shaped or spoke-like streaks pointing toward the center. These can cause problems with glare and contrast, particularly in bright light or when driving at night.

Posterior subcapsular cataracts form at the back surface of the lens, just inside the lens capsule. They tend to grow faster than other types and can be particularly disruptive because of where they sit. This type often makes it harder to read or see in bright light, since the pupil constricts in those conditions and directs more light through the affected area.

Congenital cataracts are present at birth or appear in early childhood. They may be related to genetic conditions, infections the mother had during pregnancy, or other developmental factors.

Secondary cataracts develop as a result of another medical condition, such as diabetes, or as a side effect of certain medications or medical treatments. These are sometimes called drug-induced or metabolic cataracts.

Traumatic cataracts result from a direct injury to the eye. They can develop shortly after an injury or take years to appear.

Many people develop more than one type of cataract at the same time, and the exact pattern can vary from person to person.

Cataracts usually develop slowly, so symptoms often come on gradually rather than all at once. In the early stages, many people don't notice any significant changes. Over time, as the cataract becomes denser, visual symptoms tend to become more noticeable.

Common symptoms of cataracts include:

• Blurry or hazy vision that makes things look out of focus even with glasses or contact lenses
• Difficulty seeing at night or in low-light situations
• Sensitivity to glare from sunlight, lamps, or headlights
• Halos around lights, especially when driving at night
• Faded or yellowed colors, since cataracts can affect how the eye perceives color
• Double vision in one eye, which can occur when light passing through the cloudy lens is split
• Frequent changes in your glasses or contact lens prescription, as the lens continues to change
• Difficulty reading or doing close-up tasks, particularly with posterior subcapsular cataracts

Because these symptoms develop gradually, it can be easy to dismiss them as just a normal part of getting older or attribute them to a different problem. That's why regular eye exams are so important. An eye care provider can detect changes in the lens before they significantly affect your vision or daily life.

Diagnosing cataracts involves a thorough eye examination, and it's not something you can do at home. An eye care provider uses several tools and tests to evaluate the health and clarity of the lens, rule out other possible causes of vision changes, and understand the full picture of your eye health.

A typical cataract evaluation includes:

• Visual acuity testing, which measures how clearly you can see at various distances using an eye chart
• Refraction testing, which determines whether updated glasses or contacts might improve your vision
• Slit-lamp examination, in which a special microscope with a narrow beam of light is used to look closely at the structures of the eye, including the lens
• Dilated eye exam, in which eye drops are used to widen the pupil so the provider can examine the lens, retina, and optic nerve in greater detail

In some cases, additional tests may be used to evaluate contrast sensitivity or glare, which can reveal how a cataract is affecting real-world vision beyond what a standard eye chart can show. If there are questions about other parts of the eye, imaging like optical coherence tomography (OCT) may also be used.

It's important to have a complete exam rather than relying only on your own sense of how your vision feels, since other eye conditions can cause similar symptoms and may need to be addressed alongside or instead of a cataract.

While anyone can develop cataracts, certain factors increase the likelihood and may influence how quickly they progress. Some of these risk factors are things you can't change, while others are within your control.

Non-modifiable risk factors include:

• Age, which is the single strongest risk factor for age-related cataracts
• Family history, since cataracts can run in families
• Race and ethnicity, as the risk profile can vary across different populations
• Prior eye conditions or surgeries, which can affect the lens over time

Modifiable risk factors that may be worth discussing with a healthcare provider include:

• Smoking, which has been consistently linked to higher cataract risk, particularly for nuclear cataracts
• Prolonged UV exposure without appropriate eye protection
• Unmanaged diabetes, since blood sugar levels can affect the lens
• Obesity, which has been associated with a higher likelihood of age-related cataracts
• Long-term use of corticosteroid medications

Making healthy lifestyle choices doesn't guarantee you'll never develop cataracts, but it may help preserve your eye health over time. Wearing sunglasses that block UV rays, not smoking, and keeping chronic health conditions well-managed are all reasonable steps to take.

Cataracts are widely misunderstood, and there are several persistent misconceptions that can lead people to worry unnecessarily or delay seeking care. Setting the record straight can help you approach your eye health with accurate information.

Myth: Cataracts are a film that grows over the outside of the eye. Fact: A cataract forms inside the lens of the eye, not on the surface. The eye may look normal from the outside, especially in the early stages.

Myth: Cataracts only affect older adults. Fact: While aging is the most common cause, cataracts can affect people of any age, including infants and young children.

Myth: Cataracts can be prevented with eye drops or vitamins. Fact: There is no proven medication, supplement, or eye drop that can reverse or reliably prevent cataracts. Healthy habits may help support overall eye health, but there is currently no substitute for monitoring and professional care.

Myth: Cataracts are caused by reading too much or spending too much time on screens. Fact: There is no evidence that reading or screen use causes cataracts. Fatigue from screen use is a different issue and does not damage the lens.

Myth: Cataracts always lead to blindness. Fact: Cataracts progress at different rates in different people, and many people live with early cataracts for years with only mild vision changes. Regular monitoring by an eye care provider can help ensure your vision is being managed appropriately.

Routine eye exams are the best way to catch cataracts and other eye conditions early, even before you notice any symptoms. Adults, particularly those over 40, are generally encouraged to have regular comprehensive eye exams as part of their overall health care.

That said, there are certain situations where you shouldn't wait for your next routine appointment. Reach out to an eye care provider promptly if you experience:

• Sudden changes in vision that come on quickly
• Double vision in one or both eyes
• Significant difficulty driving, reading, or completing daily tasks
• Seeing flashes of light or a sudden increase in floaters (spots or lines in your vision)
• Pain or redness in your eye alongside vision changes

These symptoms may or may not be related to cataracts, but they warrant a timely evaluation to rule out conditions that may need urgent attention. The sooner a concern is identified, the better positioned you are to protect your long-term vision.