Cataracts: When Does Clouded Vision Call for Surgery?

A cataract is a clouding of the eye's normally clear lens, and it often develops slowly with age. Surgery is usually considered when the clouding interferes with things you need or want to do, such as driving at night, reading, or recognizing faces, not simply because a cataract is present. This article explains the symptoms, how clinicians decide about surgery, what the operation involves, and which sudden vision changes need urgent care.

What a cataract is and why vision gets cloudy

The lens sits behind the pupil and focuses light onto the retina. It is made mostly of water and protein. Over time, some of that protein can clump, and the lens becomes cloudy. MedlinePlus describes a cataract as a clouding of the lens that is common in older adults and often develops slowly (MedlinePlus: Cataract).

Think of looking through a fogged or frosted window. Light still gets in, but it scatters, so images look dim, washed out, or hazy. Cataracts can affect one eye or both, and the two eyes may differ in how affected they are.

Common symptoms of a cataract

Early cataracts may cause few symptoms. As the clouding progresses, people often describe:

• Blurry, cloudy, or "foggy" vision that glasses do not fully fix
• Glare from sunlight, lamps, or oncoming headlights, and halos around lights
• Trouble seeing at night
• Colors that look faded or yellowed
• Double vision in one eye
• Needing brighter light to read, or frequent changes to your glasses prescription

Because the change is gradual, many people do not notice it until a task becomes hard. Some people notice a temporary improvement in near vision as the lens changes, though this is not a reliable or lasting effect.

What contributes to cataracts

Several factors contribute, and the exact mechanism is not fully understood. Aging is a common cause. Other factors associated with cataracts include:

• Diabetes, which is linked to earlier or faster lens changes (see MedlinePlus: Diabetic Eye Problems)
• Long-term ultraviolet light exposure from the sun
• Smoking and heavy alcohol use
• Long-term use of corticosteroid medicines
• Past eye injury or eye surgery, and some eye inflammation
• A family history of cataracts

Cataracts can also be present at birth or appear in childhood, which needs prompt evaluation by an eye specialist because a child's visual system is still developing.

How cataracts are evaluated

An eye care professional combines your history, a vision test, and an examination of the eye. This usually includes dilating the pupil so the lens and the back of the eye can be seen. The exam also checks for other conditions that can blur vision, such as glaucoma or macular degeneration, because a cloudy lens may not be the only reason vision has changed. If you are worried about those, see our articles on glaucoma and age-related macular degeneration. If your blurriness comes and goes, that pattern has its own explanations and is covered separately.

When does a cataract call for surgery?

There is no single vision number that automatically means surgery. The decision is usually shared between you and your eye surgeon, and it often rests on how much the cataract limits your daily function and safety. Questions that tend to guide the discussion include:

• Is it hard to drive, especially at night or in glare?
• Do you have trouble reading, working, cooking, or recognizing faces?
• Have you had falls or near-misses that may relate to poor vision?
• Does glare or blur limit hobbies or independence?

Surgery is also sometimes recommended when a cataract makes it hard to examine or treat another eye problem, such as diabetic eye disease. In other cases, the cataract itself causes eye problems, for example when a very swollen lens contributes to a type of glaucoma. Your surgeon can explain whether that applies to you.

If the cataract is mild and not bothering you, many clinicians suggest watching it with regular exams. Updated glasses, brighter lighting, anti-glare lenses, and magnifiers can help for a while. No eye drop, supplement, or diet has been shown to reverse an established cataract in people. Laboratory research on foods and cataract prevention is interesting but preliminary.

What cataract surgery involves

In cataract surgery, the surgeon removes the cloudy lens and usually replaces it with a clear artificial lens, called an intraocular lens. The most common technique is phacoemulsification, in which an ultrasound probe breaks the lens into small pieces that are suctioned out through a tiny incision. It is typically done as an outpatient procedure with numbing medicine and, often, light sedation.

Intraocular lenses come in different types. Some are set mainly for distance vision, and others are designed to help with a wider range of distances or to correct astigmatism. Which type fits depends on your eyes, your lifestyle, and cost, since some options are not fully covered by insurance. Ask your surgeon how each choice may affect your need for glasses afterward.

Clinical studies, including a prospective cohort of phacoemulsification surgeries listed in Sources, generally report that many people see better after uncomplicated cataract surgery, though results vary. Other eye conditions, such as macular degeneration or glaucoma, can limit how much vision improves.

Risks and what to discuss beforehand

Cataract surgery is commonly performed and is generally considered safe, but no operation is risk free. Possible complications include inflammation, infection inside the eye, swelling of the retina, retinal detachment, increased eye pressure, and clouding of the membrane behind the new lens, which can often be treated with a quick laser procedure. Tell your surgeon about all medicines you take, including blood thinners and alpha-blocker medicines used for prostate symptoms, such as tamsulosin, which can make the iris behave differently during surgery. Do not change or stop any prescription on your own. Your surgeon and prescriber can decide what is appropriate before the procedure.

Your surgeon will give you eye drops to prevent infection and reduce inflammation after surgery. Follow the instructions you are given, and tell your clinician if you have trouble using the drops.

Recovery and follow-up

Many people notice improvement fairly soon, though healing continues over the following weeks. Mild scratchiness, watering, and light sensitivity can occur. Your surgical team will tell you when to return for checks and which activities to avoid, such as rubbing the eye, swimming, or heavy lifting. Follow-up timing varies by surgeon and by how the surgery went. Researchers have compared different follow-up schedules after uncomplicated surgery, which is one reason practices differ.

If you have cataracts in both eyes, surgery is often done on one eye at a time, with a gap between operations so the first eye can be checked.

Protecting your eyes in the meantime

• Get regular eye exams, especially if you have diabetes, a family history of eye disease, or are older
• Wear sunglasses that block ultraviolet light
• Do not smoke, and talk with your clinician about help quitting
• Work with your care team on blood sugar if you have diabetes
• Use good lighting at home, and take extra care with night driving if glare is a problem

Eye care basics are summarized by MedlinePlus (MedlinePlus: Eye Care).

When sudden changes are not a cataract

Cataracts usually change vision slowly. Sudden changes point to other problems that can threaten sight and need urgent evaluation, including retinal detachment, a blocked blood vessel in the eye, a sharp rise in eye pressure, or a stroke.

Double vision deserves a closer look, because the cover test matters. Double vision that persists when only one eye is open is usually caused by the eye itself, such as the lens, cornea, or a refractive problem, and can be raised at a routine eye exam. New double vision that goes away when you cover either eye (it appears only with both eyes open) can come from eye misalignment, a nerve problem, or a problem in the brain, including stroke. It needs same-day evaluation, and a droopy eyelid, eye pain, an enlarged pupil, or severe headache alongside it can point to a nerve problem that needs emergency care. If it comes with any stroke sign, call 911. The emergency box below lists what to watch for.

When to Seek Medical Care