Cataracts explained: symptoms, surgery and common questions

What is a cataract?

Behind the pupil is the eye’s normally clear natural lens. It focuses light and helps create a sharp image on the retina. In a cataract, the lens becomes increasingly cloudy. Light is scattered more strongly, contrast is lost, and vision appears blurred or misty. [1][2]

The clouding most commonly develops as part of the natural ageing process. Diabetes, long-term corticosteroid treatment, eye injuries, inflammation, or previous procedures can also increase the risk. Both eyes are usually affected, although not always to the same degree or at the same rate. [1][2]

What symptoms are typical?

A cataract does not usually cause pain or burning eyes. The deterioration in vision often develops over months or years. For this very reason, the changes can easily be mistaken for a normal part of ageing. [2]

• Blurred, misty, or hazy vision
• More glare from sunlight, headlights, or streetlights
• Poorer vision at dusk and at night
• Faded colours and reduced contrast
• Frequently changing glasses prescription
• Differences in vision between the right and left eye

How is a cataract diagnosed?

The appointment begins with a discussion of your symptoms, medical history, medication, and visual demands in everyday life. This is usually followed by a visual acuity test and a slit-lamp examination. The slit lamp provides a magnified view of the lens and allows the type and extent of clouding to be assessed. [1][2]

Depending on the clinical question, eye pressure, the back of the eye, and the retina may also be examined. This is important because other conditions—such as macular changes or glaucoma—can also affect vision and influence the result that can realistically be expected from surgery.

When should surgery be considered?

There is no single right time for cataract surgery that applies to everyone. What matters is how much your vision affects daily life: Is reading difficult? Does driving at night feel unsafe? Are work, mobility, or hobbies restricted? If there are hardly any symptoms, there is often no need to rush into surgery. [2][3]

The decision is made together with you. In addition to your symptoms, the findings in your eyes, other eye conditions, occupational needs, and personal expectations all play a role. A very advanced cataract can make eye measurements and surgery more difficult, which is why regular follow-up examinations are useful. [2]

What happens during surgery?

In standard cataract surgery, the cloudy lens is broken up and removed through a small incision. A clear artificial lens is then placed in the remaining lens capsule. The procedure is usually performed as an outpatient under local anaesthesia using drops, gel, or an injection. [2][3]

Before surgery, the eye is measured so that the power of the artificial lens can be calculated. A monofocal lens generally provides clear focus at one distance; glasses are usually still needed for other distances. Toric or multifocal lenses may be suitable for selected people, but they have their own advantages and disadvantages. These can include halos, glare or other unwanted visual effects and reduced contrast sensitivity. Lens selection should therefore be individual and made without time pressure.

Cataract surgery is well established and often improves vision, but no operation is risk-free. Possible complications include infection, inflammation, retinal problems, pressure changes, residual refractive error and, rarely, permanent loss of vision. Individual risks should be discussed with the surgeon. [2][3]

What is important after surgery?

After the operation, eye drops and follow-up appointments are arranged according to your individual findings. You should not rub the eye. The surgical team will tell you when it is safe to resume exercise, driving, swimming, or heavy physical work. [2]

The artificial lens itself cannot develop another cataract. However, months or years later, the back of the remaining lens capsule can become cloudy. This is called posterior capsule opacification, or a secondary cataract, and it can usually be treated with a brief outpatient laser procedure. [2]