Cataract: Symptoms, Causes & Surgery Treatment

What Is a Cataract?

A cataract is a clouding of the eye's natural lens that sits behind the iris and pupil. This clouding prevents light from passing through clearly, causing blurred or dimmed vision. Cataracts typically develop slowly over months to years and are the leading cause of blindness worldwide, accounting for approximately 51% of global blindness.

The lens of the eye is normally clear and transparent, allowing light to pass through and focus on the retina at the back of the eye. The lens is located behind the colored part of the eye (the iris) and the pupil, held in place by an elastic lens capsule. In a healthy eye, the lens can change shape to focus on objects at different distances, though this ability gradually decreases with age.

When a cataract develops, proteins in the lens begin to break down and clump together, creating cloudy areas that scatter light instead of allowing it to pass through cleanly. This process is similar to how a window becomes frosted or foggy. The cloudiness typically starts small and may not noticeably affect vision at first, but it gradually grows larger over time, progressively obscuring more and more of the visual field.

Cataracts can develop in one or both eyes, though they don't spread from one eye to the other. When both eyes are affected, the cataract in one eye often progresses faster than the other, leading to different degrees of vision impairment between the two eyes. This asymmetry can sometimes help people cope because the better eye compensates for the weaker one, though it can also delay diagnosis and treatment.

Types of Cataracts

There are several types of cataracts, classified by their location within the lens or their cause. Nuclear cataracts form in the center of the lens and are most commonly associated with aging. Cortical cataracts begin at the edges of the lens and gradually extend inward like spokes on a wheel. Posterior subcapsular cataracts form at the back of the lens, directly in the path of light, and tend to progress more quickly than other types.

Some cataracts are present at birth (congenital cataracts) or develop in childhood, though these are relatively rare. Secondary cataracts can develop as a result of other eye conditions, medical treatments (especially corticosteroid medications), or systemic diseases like diabetes. Traumatic cataracts can develop after an eye injury, sometimes years after the initial trauma occurred.

How Common Are Cataracts?

Cataracts are extremely common, particularly among older adults. By age 65, approximately one-third of people have some degree of cataract formation. By age 75, more than half of all people either have cataracts or have already undergone cataract surgery. Globally, cataracts remain the leading cause of blindness, responsible for approximately 51% of world blindness, though this is largely preventable through surgery.

What Are the Symptoms of Cataracts?

Cataract symptoms develop gradually and include blurred or cloudy vision, increased sensitivity to light and glare, difficulty seeing at night, faded or yellowed colors, double vision in one eye, and frequent changes in glasses prescription. Many people initially mistake early symptoms for simply needing new glasses.

The symptoms of cataracts typically develop slowly over months to years, which is why many people don't realize they have cataracts until the condition has progressed significantly. In the early stages, you might not notice any symptoms at all, or you might attribute changes in your vision to normal aging or the need for stronger glasses. As the cataract grows larger and clouds more of the lens, symptoms become more noticeable and begin to interfere with daily activities.

One of the most common early symptoms is a gradual blurring or dimming of vision, as if looking through a dirty or frosted window. Colors may appear faded, washed out, or yellowed, making it harder to distinguish between similar shades. This happens because the cataract absorbs and scatters certain wavelengths of light, altering how colors appear to the brain.

Many people with cataracts experience increased sensitivity to light and glare, particularly from bright lights or sunlight. Driving at night can become especially challenging because oncoming headlights may appear to have halos around them or cause uncomfortable glare. This light sensitivity occurs because the cloudy lens scatters light rays instead of focusing them precisely on the retina.

Vision Changes at Different Distances

People with cataracts often notice that their vision has changed in specific ways at different distances. Reading fine print may become more difficult, requiring brighter light and larger text. Distant objects may appear less sharp or defined. Some people experience a temporary improvement in near vision called "second sight," which occurs when the cataract changes the focusing power of the lens. However, this improvement is temporary and eventually gives way to worsening vision as the cataract progresses.

Double Vision and Contrast Problems

Cataracts can cause double vision in the affected eye (monocular diplopia), meaning you see two overlapping images even when looking with just one eye. This happens because irregularities in the cloudy lens create multiple focal points. Additionally, contrast sensitivity decreases, making it harder to distinguish objects from their backgrounds, particularly in low-light conditions. This can affect activities like reading, recognizing faces, and navigating stairs.

What Causes Cataracts?

Cataracts are primarily caused by aging, as proteins in the lens break down and clump together over time. Other risk factors include diabetes, smoking, excessive alcohol consumption, prolonged sun exposure, certain medications (especially corticosteroids), eye injuries, and genetic factors. Some cataracts are present at birth.

The most common cause of cataracts is the natural aging process. The lens of the eye is made mostly of water and protein, and as we age, these proteins begin to break down and aggregate, forming clumps that cloud the lens. This process is somewhat similar to how an egg white turns from clear to opaque when cooked, though it occurs much more slowly in the eye. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.

While aging is the primary cause, several other factors can accelerate cataract formation or cause cataracts to develop at younger ages. Understanding these risk factors can help you take steps to protect your eye health and potentially slow the progression of cataracts.

Oxidative stress plays a significant role in cataract development. Free radicals, which are unstable molecules produced by normal metabolism and environmental exposures, can damage lens proteins and cell membranes. This damage accumulates over time, contributing to the protein aggregation that causes lens clouding. Factors that increase oxidative stress, such as smoking and excessive sun exposure, are associated with higher cataract risk.

Medical Conditions and Medications

Diabetes is a significant risk factor for cataracts. People with diabetes are 2-5 times more likely to develop cataracts, often at younger ages. High blood sugar levels can cause changes in the lens that accelerate protein aggregation. Additionally, diabetic cataracts tend to progress more quickly and may require surgery sooner than age-related cataracts.

Certain medications, particularly corticosteroids, significantly increase cataract risk. Long-term use of oral corticosteroids, inhaled steroids for asthma, or steroid eye drops can all contribute to cataract formation. Other medications linked to increased cataract risk include some psychiatric medications, certain diuretics, and hormone replacement therapy.

Lifestyle and Environmental Factors

Smoking doubles the risk of cataract development and is one of the most important modifiable risk factors. Tobacco smoke contains numerous oxidative compounds that directly damage lens proteins. The good news is that quitting smoking can reduce your future cataract risk, though damage already done cannot be reversed.

Prolonged exposure to ultraviolet (UV) radiation from sunlight accelerates cataract formation. People who spend significant time outdoors, particularly in sunny climates or at high altitudes where UV exposure is more intense, have higher rates of cataracts. Wearing sunglasses that block UV rays and wide-brimmed hats can help protect your eyes.

How Are Cataracts Diagnosed?

Cataracts are diagnosed through a comprehensive eye examination that includes a visual acuity test (reading letters on an eye chart), a slit-lamp examination to view the lens under magnification, and a dilated eye exam. Your eye doctor can see the cataract's size, location, and how much it affects your vision.

If you're experiencing symptoms that might indicate cataracts, the first step is to schedule a comprehensive eye examination with an optometrist or ophthalmologist. During this exam, your eye care professional will conduct several tests to evaluate your vision and examine the internal structures of your eyes. The examination is painless and typically takes about an hour, including time for eye drops to take effect.

The diagnostic process begins with a thorough discussion of your symptoms, medical history, and any medications you're taking. Your doctor will ask about when you first noticed vision changes, how your symptoms have progressed, and how they affect your daily activities. This information helps determine whether your symptoms are consistent with cataracts and guides treatment decisions.

Visual Acuity Testing

Visual acuity testing measures how well you can see at various distances. You'll be asked to read letters on an eye chart (Snellen chart), typically from 20 feet away. The doctor will test each eye separately, both with and without your current glasses or contact lenses. This test provides a standardized measurement of your vision that can be compared over time to track any changes.

Slit-Lamp Examination

The slit-lamp examination is a crucial part of cataract diagnosis. A slit lamp is a specialized microscope that allows your doctor to examine the structures at the front of your eye in great detail using a bright, thin beam of light. You'll sit with your chin and forehead resting against supports to keep your head steady while the doctor examines your cornea, iris, and lens.

Through the slit lamp, your doctor can see the location, size, and density of any cataracts. This helps determine the type of cataract you have and how much it is contributing to your vision problems. The examination also checks for other eye conditions that might affect your vision or surgical options.

Dilated Eye Examination

For a more thorough examination, your doctor will use eye drops to dilate (widen) your pupils. This allows more light to enter the eye and gives the doctor a better view of the lens and the retina at the back of the eye. The drops take about 20-30 minutes to fully work and can cause temporary light sensitivity and blurred near vision that may last several hours.

With your pupils dilated, the doctor can examine the entire lens for cataracts and also check the retina for other conditions that might affect your vision, such as macular degeneration or diabetic retinopathy. This comprehensive evaluation ensures that cataracts are correctly identified as the cause of your vision problems and that no other conditions are overlooked.

When Should You See a Doctor About Cataracts?

Schedule an eye examination if you notice blurred vision, increased light sensitivity, difficulty seeing at night, faded colors, or if you haven't had an eye exam in over a year (especially if you're over 60). Seek immediate care if you experience sudden vision loss, severe eye pain, or sudden onset of floaters or flashes of light.

Many people with early cataracts don't notice significant symptoms, which is why regular eye examinations are so important, particularly for adults over 60. The American Academy of Ophthalmology recommends comprehensive eye exams every 1-2 years for people over 65, or more frequently if you have risk factors like diabetes or a family history of eye disease.

If you notice any changes in your vision, don't assume they're simply a normal part of aging. While cataracts are common and usually not urgent, the same symptoms can sometimes indicate other eye conditions that require prompt treatment. Only a comprehensive eye examination can determine the cause of your vision changes and whether treatment is needed.

Contact your eye doctor promptly if your vision changes are affecting your quality of life or ability to perform daily activities. This includes difficulty reading, watching television, recognizing faces, driving (especially at night), or doing your job. Even if your symptoms seem mild, it's better to have them evaluated so you can make informed decisions about monitoring versus treatment.

How Are Cataracts Treated?

Surgery is the only effective treatment for cataracts. During cataract surgery, the cloudy natural lens is removed and replaced with a clear artificial lens (intraocular lens or IOL). The procedure takes 10-15 minutes, is performed under local anesthesia, and has a success rate exceeding 95%. Not everyone with cataracts needs surgery; monitoring may be appropriate if vision is adequate for daily activities.

Unlike many medical conditions, cataracts cannot be treated with medications, eye drops, or lifestyle changes. Once a cataract has formed, the only way to restore clear vision is through surgical removal of the cloudy lens and implantation of an artificial lens. However, not everyone with cataracts needs surgery immediately. The decision depends on how much the cataract affects your vision and daily life.

In the early stages of cataract development, symptoms may be mild enough that they can be managed with stronger glasses, better lighting, magnifying lenses for reading, or anti-glare sunglasses. Your eye doctor may recommend monitoring your cataracts with regular examinations to track their progression. Many people live comfortably with mild cataracts for years before surgery becomes necessary.

Surgery is typically recommended when cataracts significantly impair your ability to perform daily activities, such as reading, driving, or working. The decision is highly individual and depends on your specific visual needs, lifestyle, and how much the cataract bothers you. Some people with demanding visual requirements may choose surgery earlier, while others may delay surgery if their symptoms are manageable.

Cataract Surgery Procedure

Modern cataract surgery is one of the most commonly performed and successful surgical procedures in the world. The standard technique, called phacoemulsification, uses ultrasound energy to break up the cloudy lens into tiny fragments that are then suctioned out of the eye. An artificial intraocular lens (IOL) is then inserted to replace the natural lens and restore clear vision.

The surgery is typically performed as an outpatient procedure, meaning you go home the same day. Before the procedure, you'll receive anesthetic eye drops to numb the eye, and possibly a mild sedative to help you relax. You'll be awake during the surgery but won't feel any pain. The entire procedure usually takes about 10-15 minutes, though you'll be at the surgical center for several hours including preparation and recovery time.

The surgeon makes a tiny incision (usually 2-3 millimeters) at the edge of the cornea. Through this incision, they insert a small probe that emits ultrasound waves to break up the cloudy lens. The fragmented lens material is then suctioned out through the same probe. The artificial lens is folded, inserted through the incision, and positioned in the lens capsule where it unfolds and stays in place. The incision is self-sealing in most cases and doesn't require stitches.

Types of Intraocular Lenses (IOLs)

Several types of artificial lenses are available, and your surgeon will help you choose the best option for your needs. Monofocal IOLs are the most common type and provide clear vision at one distance, usually far. You'll typically still need reading glasses for close-up tasks. Multifocal and accommodating IOLs can provide clear vision at multiple distances, potentially reducing or eliminating the need for glasses, though they may cause more glare or halos around lights.

Toric IOLs are designed to correct astigmatism in addition to cataracts. If you have significant astigmatism, a toric lens can provide clearer vision without glasses than a standard monofocal lens. Extended depth of focus (EDOF) lenses provide a continuous range of quality vision from far to intermediate distances, which is useful for activities like computer work and driving.

What Is Recovery Like After Cataract Surgery?

Most people notice improved vision within a few days after cataract surgery. Full recovery takes 4-6 weeks. During this time, you'll use anti-inflammatory eye drops and should avoid rubbing your eye, heavy lifting, swimming, and getting water in your eye. Most patients can return to light activities within a day or two.

After cataract surgery, you'll rest briefly in a recovery area while the effects of any sedation wear off. Your eye will be covered with a protective shield, which you'll need to wear while sleeping for about a week to prevent accidentally rubbing or pressing on the eye. You'll need someone to drive you home because your vision will still be blurry from the dilating drops used during surgery.

Most people notice some improvement in their vision within a few days of surgery, though complete healing takes 4-6 weeks. Your vision may be blurry at first as your eye adjusts to the new lens. Colors may appear brighter or more vivid than you remember, as the new clear lens lets through more light than your cloudy natural lens did. Some people describe this as seeing the world in high definition for the first time in years.

During the recovery period, you'll use prescription eye drops several times daily to prevent infection and reduce inflammation. Follow your surgeon's instructions carefully regarding drop schedules and any activity restrictions. Common restrictions during recovery include avoiding heavy lifting, bending at the waist, rubbing or pressing on the eye, swimming or hot tubs, dusty or dirty environments, and eye makeup.

Follow-Up Care

You'll typically have a follow-up appointment the day after surgery, then again at about one week, and at approximately 4-6 weeks post-surgery. At these visits, your surgeon will check your healing, measure your vision, and ensure there are no complications. Once your eye has fully healed (usually 4-6 weeks after surgery), you can have your eyes tested for new glasses if needed.

If you need surgery on both eyes, they're typically done separately, usually 1-4 weeks apart. This allows the first eye to heal and your brain to adapt to the new lens before the second surgery. It also provides a safety margin in case of complications, though serious complications are rare.

Possible Complications

Cataract surgery is very safe, with serious complications occurring in less than 1% of cases. The most common complication is posterior capsule opacification (PCO), sometimes called "secondary cataract" or "after-cataract," which develops in about 20% of patients months to years after surgery. PCO occurs when the capsule that holds the artificial lens becomes cloudy. It's easily treated with a quick, painless laser procedure called YAG capsulotomy.

Rare but serious complications can include infection inside the eye (endophthalmitis), bleeding, retinal detachment, and persistent inflammation. Contact your doctor immediately if you experience severe pain, significant vision loss, increasing redness, or any symptoms that concern you after surgery.

Can Cataracts Be Prevented?

While cataracts cannot be completely prevented, you can reduce your risk and slow their progression by wearing UV-protective sunglasses, not smoking, managing diabetes carefully, limiting alcohol, eating a diet rich in antioxidants, and having regular eye exams to catch cataracts early.

Since aging is the primary cause of cataracts, they cannot be entirely prevented. However, research suggests that certain lifestyle choices may help reduce your risk of developing cataracts or slow their progression. While none of these measures guarantee prevention, they contribute to overall eye health and general well-being.

Protecting your eyes from ultraviolet radiation is one of the most important preventive measures. Wear sunglasses that block 99-100% of UVA and UVB rays whenever you're outdoors, even on cloudy days. A wide-brimmed hat provides additional protection. UV exposure accumulates over a lifetime, so it's never too early or too late to start protecting your eyes.

If you smoke, quitting is one of the most effective steps you can take to protect your eye health. Smoking significantly increases cataract risk and accelerates their progression. Within 10-15 years of quitting, former smokers' cataract risk approaches that of people who never smoked. Your doctor can provide resources to help you quit.

Nutrition and Eye Health

A diet rich in fruits and vegetables, particularly those high in antioxidants like vitamins C and E, may help protect against cataracts. Antioxidants help neutralize free radicals that can damage lens proteins. Good sources include citrus fruits, berries, leafy greens, nuts, and whole grains. Some studies suggest that omega-3 fatty acids from fish may also be beneficial.

Limiting alcohol consumption is associated with lower cataract risk. Heavy drinking has been linked to increased oxidative stress in the lens. If you drink alcohol, do so in moderation, defined as up to one drink per day for women and up to two for men.

Managing Health Conditions

If you have diabetes, maintaining good blood sugar control is essential for protecting your vision. Poorly controlled diabetes accelerates cataract formation and increases the risk of other serious eye conditions like diabetic retinopathy. Work closely with your healthcare team to manage your blood sugar, blood pressure, and cholesterol.

Be aware of medications that may increase cataract risk, particularly corticosteroids. If you need long-term steroid treatment, discuss eye health monitoring with your doctor. Never stop prescribed medications without consulting your healthcare provider, but ask about alternatives if you're concerned about cataract risk.