Cataract: Symptoms, Types, Surgery and Recovery Explained

A cataract is a clouding of the natural lens inside your eye. That lens sits just behind the coloured iris and normally stays crystal clear, focusing light sharply onto the retina at the back of the eye. Over the years the proteins in the lens slowly change, clump together and scatter light, so the world gradually looks dimmer, blurrier and less colourful. According to the World Health Organization, cataract remains the leading cause of blindness worldwide, yet it is also one of the most successfully treatable conditions in all of medicine.

The good news is that cataract surgery is safe, quick and highly effective for most people. The less obvious news is that there is no eye drop, diet or exercise that reverses an established cataract. This guide explains how cataracts develop, which symptoms to watch for, how an eye doctor confirms the diagnosis, what happens during modern surgery, how to choose a lens implant and what recovery is really like.

What happens in the eye when a cataract forms

The lens is made mostly of water and tightly packed, precisely arranged proteins. That orderly structure is what keeps it transparent. With age, oxidative stress, ultraviolet light, high blood sugar and other factors, these proteins break down and stick together. The result is cloudy patches or a general yellow-brown tint that blocks and scatters incoming light. You can read more about how the lens fits into the optical system in our guide to the anatomy of the eye.

Cataracts usually develop slowly over years. Many people over 60 have some lens changes without noticing much difference in daily life. Treatment becomes worthwhile when the clouding starts to interfere with activities that matter to you, such as reading, driving or recognising faces.

Types of cataract

Eye doctors describe cataracts by where the clouding sits in the lens and by what caused it. The type influences which symptoms appear first and how quickly vision changes.

Many people have a mixture of types. Cataracts in children are rare but important, because a clear image is needed during early childhood for the visual brain to develop normally. See our guide to strabismus and amblyopia for why early treatment matters.

Symptoms: how a cataract feels in daily life

Cataracts are painless. They do not cause redness, discharge or itching. Instead, the changes are visual and creep in slowly, which is why many people adapt without realising how much they have lost until after surgery.

• Cloudy, misty or blurred vision, as if looking through a dirty window or frosted glass.
• Glare and halos around lights, particularly oncoming headlights at night. Our article on night driving and glare explains this effect.
• Faded or yellowed colours; whites may look cream and blues may look darker.
• Needing more light to read or do close work.
• Frequent changes in glasses prescription, often a shift towards nearsightedness.
• Double vision in one eye (monocular diplopia) in some cases.
• Reduced contrast, making steps, kerbs and faces harder to see, which raises the risk of falls in older adults.

Risk factors

Age is by far the strongest risk factor, but several other factors make cataracts appear earlier or progress faster. Some of these can be changed.

• Ageing: almost everyone develops some lens clouding if they live long enough.
• Diabetes: high blood sugar alters the lens chemistry; people with diabetes tend to develop cataracts earlier.
• Smoking: strongly associated with nuclear cataract. Read more in smoking and eye disease.
• Ultraviolet light: long-term sun exposure without protection is linked with cortical cataract.
• Steroid medicines: long-term oral, inhaled or eye-drop corticosteroids can cause posterior subcapsular cataract.
• Eye injury, eye surgery or inflammation, such as previous retinal surgery or uveitis.
• Heavy alcohol use, high myopia and family history.
• Radiation exposure, including radiotherapy to the head.

How cataract is diagnosed

A cataract is diagnosed during a comprehensive eye examination by an optometrist or ophthalmologist. The tests are painless and usually include:

1. Visual acuity test using a letter chart to measure how clearly you see at distance and near.
2. Refraction to check whether new glasses could still improve your vision.
3. Slit-lamp examination, in which a microscope with a bright beam lets the clinician see the type and density of the cataract.
4. Dilated fundus examination with drops that widen the pupil, so the retina and optic nerve can be checked for other causes of poor vision, such as macular degeneration or glaucoma.
5. Glare or contrast testing in some clinics, to show how much the cataract affects real-world vision.

If surgery is planned, additional measurements (biometry) are taken to calculate the power of the replacement lens. Our guide to eye examinations explains each step in more detail.

When is surgery needed?

There is no fixed vision level at which surgery must happen. The modern approach is to operate when the cataract affects your quality of life or safety: difficulty driving, reading, working, watching television or moving around confidently. In the early stages, stronger glasses, brighter task lighting, anti-glare sunglasses and magnifiers may be enough.

Waiting does not usually harm the eye, but very advanced (hypermature) cataracts can make surgery more complex and occasionally cause raised eye pressure or inflammation. For drivers, it is important to know that cataracts can drop vision below the legal driving standard, so regular checks matter.

Cataract surgery: how phacoemulsification works

The standard operation in most countries is called phacoemulsification, often shortened to phaco. It is one of the most frequently performed operations in the world.

1. Preparation: drops dilate the pupil and numb the eye. Most people stay awake; a light sedative may be offered. General anaesthetic is reserved for special cases.
2. Small incision: the surgeon makes a tiny self-sealing cut, usually 2 to 3 mm, at the edge of the cornea.
3. Opening the capsule: a round opening is made in the thin bag (capsule) that holds the lens.
4. Breaking up the lens: an ultrasound probe breaks the cloudy lens into small fragments and gently suctions them out.
5. Implanting the IOL: a folded artificial lens is inserted through the same small incision and unfolds inside the capsule.
6. Finishing: stitches are rarely needed. A shield is placed over the eye and you usually go home the same day.

The procedure typically takes 15 to 30 minutes. Some clinics offer femtosecond laser-assisted cataract surgery (FLACS), where a laser performs some steps such as the capsule opening. Large studies have not shown that it gives clearly better visual results than standard phaco for most patients, and it costs more. When both eyes need surgery, they are usually done on separate days. For a step-by-step patient view, see cataract surgery: what to expect.

Choosing an intraocular lens (IOL)

Your new lens is permanent and does not wear out. Choosing the type is a conversation between you and your surgeon, based on your eyes, lifestyle, budget and tolerance for compromises.

If you have astigmatism, a toric lens may give sharper uncorrected vision. People with other eye conditions such as advanced glaucoma or macular disease are often advised to choose a monofocal lens, because multifocal designs split the light and can reduce contrast.

Recovery after cataract surgery

Most people notice brighter colours and clearer vision within a few days, although full stabilisation takes several weeks.

• First day: vision is often blurry and the eye may feel gritty or watery. Wear the shield at night as instructed.
• Eye drops: you will use antibiotic and anti-inflammatory drops for a few weeks. Follow the schedule exactly; ask the clinic to show you the correct technique if needed.
• Activities: light daily activities are usually fine within a day or two. Avoid rubbing the eye, swimming, dusty environments and eye makeup for roughly one to two weeks, or as advised.
• Driving and work: depends on your vision and your surgeon's advice; many people return to desk work within a few days.
• New glasses: a final prescription is usually checked about four to six weeks after surgery.

Possible complications

Serious complications are uncommon, but no surgery is risk-free. Possible problems include inflammation, raised eye pressure, swelling at the centre of the retina (cystoid macular oedema), infection inside the eye (endophthalmitis, rare but serious), retinal detachment and a dislocated lens. The most common later issue is posterior capsule opacification, sometimes called a secondary cataract, where the capsule behind the implant becomes hazy months or years later. It is quickly treated with a painless YAG laser procedure in the clinic.

Prevention, myths and facts

Can cataracts be prevented?

There is no proven way to prevent age-related cataract completely, but you can reduce some risks: wear sunglasses with full UV protection and a brimmed hat outdoors, avoid smoking, keep diabetes well controlled, use steroid medicines only as prescribed, protect your eyes from injury and eat a diet rich in vegetables and fruit. See our nutrition for eye health guide. Large trials such as AREDS found that high-dose vitamin supplements did not significantly prevent or slow cataract.

Common myths

When to see a doctor

Book a routine eye examination if your vision has become gradually cloudy, you struggle with glare when driving at night, colours look faded, or your glasses no longer seem to help. Regular checks are especially important if you are over 60, have diabetes or take long-term steroid medicines.