WHAT YOU NEED TO KNOW
- Cataract is the loss of transparency of the crystalline lens, the eye’s natural lens.
- It can only be treated with surgery, which replaces the natural lens with an intraocular lens chosen for each eye.
- The decision to operate depends on the impact on daily life; the result also depends on the health of the rest of the eye.
This guide brings together, on one page, the essentials of cataract: the symptoms, when to operate, the tests, choosing the lens, surgery and recovery, the risks and what to expect in the long term. Each chapter ends with links to the articles where each topic is covered in depth.
What cataract is
The crystalline lens is the eye’s natural lens, located behind the iris, which helps focus images on the retina. Cataract is the loss of transparency of this lens. The most common cause is ageing, but it can also appear in younger people, after injuries or associated with diseases such as diabetes, and with medicines such as corticosteroids.
Cataract is not a film on the surface of the eye and cannot be removed with drops or exercises. It is a change in the lens itself, which usually develops over years.
Read moreCataract: the condition page
Symptoms
- Gradually cloudy, hazy or blurred vision.
- Glare in bright light and difficulty driving at night.
- Colours look less vivid or yellowish.
- Frequent changes in glasses prescription.
These symptoms can also have other causes, such as diseases of the retina or optic nerve, so they should be assessed in consultation.
When to operate
There is no cataract “grade” at which surgery becomes compulsory. The decision considers the difficulty in daily activities, such as reading, driving or working, the test results and each person’s needs. In the early stages, updating glasses and improving lighting may be enough.
In some situations surgery is advised for other clinical reasons, for example when the thick lens narrows the eye’s drainage angle and increases the risk of angle-closure glaucoma, or when the cataract prevents examination and treatment of the retina.
Tests before surgery
Before surgery, the eye is measured precisely to calculate the power of the intraocular lens: the length of the eye, the curvature and shape of the cornea and other measurements, taken with optical biometry devices. The health of the cornea, retina and optic nerve is also assessed, as it affects the visual result.
Always tell the team about all medicines you take or have taken, including prostate medicines, which can make pupil dilation harder, and anticoagulants.
Choosing the intraocular lens
There is no lens that is best for everyone. The choice considers the measurements, eye health and each person’s activities:
- Monofocal lenses: sharp vision at one distance, usually far, with glasses for near. They can be combined in monovision, with one eye for distance and the other for near.
- Extended depth of focus lenses and trifocal: extend vision across several distances, with a higher chance of halos and glare at night.
- Toric lenses: also correct corneal astigmatism and are available in the various focus options.
It helps to come to the consultation with clear priorities: which distances you use most, whether you drive a lot at night, and for which tasks you accept continuing to wear glasses.
Read moreHow do I choose an intraocular lens? Astigmatism and lens choice
What surgery involves
The usual technique is phacoemulsification: through a micro-incision, ultrasound breaks up the cloudy lens, which is aspirated. The capsule that surrounded it is preserved and supports the intraocular lens, which is folded, inserted and unfolds in place.
Surgery is usually done as a day case, with local or topical (drops) anaesthesia, and you go home the same day, accompanied. As a rule, one eye is operated on at a time. To align toric lenses, digital guidance systems such as VERION and CALLISTO eye overlay reference marks on the microscope image.
Some eyes need more planning: pupils that dilate poorly, weak lens support fibres, very dense cataracts or previously operated eyes. In these cases, surgery may take longer and recovery may be slower.
Read moreVERION and CALLISTO eye Cataract surgery: difficult cases Phacoemulsification animation
Recovery
In the first days, vision may be hazy or fluctuating and there may be light sensitivity. The pupil may stay dilated for up to 48 hours. Improvement is usually quick, but varies from person to person.
- Use the drops exactly as prescribed and wash your hands first.
- Do not rub or press the operated eye and keep water out of it.
- Wait for permission before swimming, physical exertion and driving again.
- If you need new glasses, the prescription is usually done about a month later, when vision has stabilised.
Contact the team or an emergency department immediately if you have severe or increasing pain, a marked drop in vision, worsening after improving, increasing redness or discharge.
Read moreAfter cataract surgery Leaflet on care after surgery
Risks and limits
Cataract surgery is now a very predictable procedure but, like any surgery inside the eye, it has risks. Serious complications are rare: infection, persistent inflammation, swelling of the cornea or retina, raised eye pressure and retinal detachment, the latter more common in high myopia.
The visual result also depends on the health of the cornea, retina and optic nerve: surgery removes the cataract but does not correct other diseases. And even with multifocal lenses, it is not always possible to do without glasses entirely.
Years later: the “dirty lens”
Months or years after surgery, the capsule holding the intraocular lens can become cloudy and vision becomes hazy again. It is not the lens getting dirty, nor the cataract coming back: once removed, the natural lens cannot form a cataract again. It is treated with a quick, painless laser, YAG capsulotomy, done in the clinic.
Read morePosterior capsule opacification
Cataract and glaucoma
Cataract and glaucoma often occur in the same person. Cataract surgery can be an opportunity: in eyes with a narrow angle, replacing the thick natural lens with a thin intraocular lens widens the drainage angle and can lower pressure lastingly. In selected cases, cataract surgery can be combined with glaucoma surgery. If you have glaucoma, the lens choice and surgical plan take into account the state of the optic nerve and visual field.
Read moreComplete guide to glaucoma Can laser or surgery cure glaucoma?
What if I don’t have cataract yet?
The same technique can be used to replace a still-clear lens, in order to reduce dependence on glasses: this is refractive lens exchange. It is mainly considered from the age of 50 to 55, when presbyopia has set in, and for high prescriptions. It is a different decision from cataract surgery and requires its own assessment of benefits, alternatives and risks.
Read moreRefractive lens surgery
Clinical sources
ESCRS · Recommendations for cataract surgery
National Eye Institute · Cataracts
Royal College of Ophthalmologists · Refractive lens exchange
This information does not replace an individual medical assessment. Follow the advice of the team looking after you.
Clinical responsibility: Dr. Nuno Lopes · Ophthalmology
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