Cataract surgery

01 · Overview

Overview

Replacing a lens that has become cloudy

Inside the eye, behind the iris, is a natural transparent lens — the crystalline lens — which helps focus images. With age, this lens loses its transparency: this is a cataract.

Vision gradually becomes blurred and hazy, colours fade, lights cause glare — headlights at night, low-angle sunlight — and changes in glasses are no longer enough to correct the visual difficulty.

The procedure consists of removing the cloudy crystalline lens and replacing it with a transparent artificial intraocular lens, positioned in exactly the same place. The crystalline lens is broken up with ultrasound and then aspirated through a very small incision; the intraocular lens is inserted folded and then unfolded inside the eye.

It is now one of the most commonly performed procedures in the world. It is brief, generally carried out under local anaesthesia with eye drops, and as day surgery.

The fundamental limitation to understand

The procedure replaces a lens. It does not repair the rest of the eye.

If the retina, optic nerve or macula is affected — by age-related degeneration, diabetes-related disease or advanced glaucoma — vision will remain limited by these conditions, even with a perfectly positioned intraocular lens. The cataract haze disappears; what it had been hiding becomes visible.

This is why examining the back of the eye before surgery is essential: it allows a realistic outcome to be explained beforehand rather than discovered afterwards.

02 · Indications

Indications

When should surgery be considered?

The decision is based not on how the crystalline lens looks during examination, but on the difficulties experienced:

• reduced vision affecting reading, driving, work or everyday activities;
• troublesome glare, particularly at night;
• frequent and inadequate changes in spectacle correction;
• double vision in one eye, halos;
• particular situations in which the cloudy crystalline lens prevents the monitoring or treatment of another eye condition.

There is no need to wait for a cataract to become “ripe”. Conversely, a very advanced cataract makes the procedure technically more difficult.

03 · The intraocular lens

The intraocular lens

A choice that should be discussed

Several types of intraocular lens exist, and the choice affects vision for years to come.

Monofocal intraocular lens

It provides clear vision at one distance only, usually far away. Reading glasses are therefore still required. This is the most established option, with the best quality of vision under difficult conditions.

Toric intraocular lens

It also corrects pre-existing astigmatism. It must be positioned along a precise axis, and later rotation may require repositioning.

Extended-depth-of-focus or multifocal intraocular lenses

They aim to reduce dependence on glasses by providing useful vision at several distances. Their trade-off must be stated clearly: halos and glare around lights, especially at night, and sometimes lower contrast perception. These effects often lessen over time but may persist, and some people tolerate them poorly, particularly those who drive frequently at night. These lenses are not suitable for every eye.

The choice of intraocular lens must be explained and understood. It is based on eye measurements, the condition of the retina, lifestyle and visual priorities. A premium lens is not a better lens: it is a different lens with different compromises. Being offered one without its disadvantages being explained should be a warning sign.

04 · Preparation

Preparation

Before the procedure

The assessment includes a complete ophthalmological examination, examination of the back of the eye, measurement of intraocular pressure, analysis of the cornea and often imaging of the macula.

One examination is decisive: biometry, which precisely measures the dimensions of the eye in order to calculate the power of the intraocular lens. The correction achieved after surgery depends on this measurement. Any history of laser refractive surgery must be reported: it changes the calculation.

Additional measures include treating any previous eye infection or inflammation, managing dry eye, and reporting all medication — certain urological medicines alter the behaviour of the iris during surgery and must be known to the surgeon.

05 · Aftercare

Aftercare

After the procedure

Vision

Often improved from the first few days, but blurred and fluctuating at first. It stabilises over several weeks.

Discomfort

A gritty sensation, watering and sensitivity to light during the first few days.

Eye drops

Local treatment is prescribed for several weeks and must be followed rigorously: it is the main means of preventing infection and inflammation.

Protection

A protective shield at night as instructed, sunglasses, and no rubbing of the eye.

Precautions

Avoid swimming pools, hammams, eye make-up, dust and significant exertion for the specified period.

Glasses

The final prescription is issued only after the vision has stabilised, usually after a few weeks.

Second eye

Operated on at a later stage, after an interval determined by the surgeon.

The emergency signs you must know

A decrease in vision, increasing pain or significant redness in the days following surgery may indicate an infection inside the eye. This complication is rare, but it is an emergency in which hours matter: without immediate treatment, it can permanently compromise vision.

It most often occurs between the second and seventh day, frequently after returning home. It is therefore essential to know whom to contact and where to seek emergency care, and never to wait in the hope that it will pass.

06 · Outcomes

Outcomes

What can reasonably be expected

The improvement is generally clear: sharper vision, colours restored and less glare.

Some important details:

• some residual refractive error is common — biometry is an estimate, not a guarantee. Glasses may still be required for distance as well as near vision;
• with a monofocal intraocular lens, reading glasses will be required;
• the outcome is limited by the condition of the retina and optic nerve;
• the intraocular lens itself does not wear out and is not routinely replaced: it remains in place for life.

“Secondary cataract.” Several months or years after surgery, the thin capsule supporting the intraocular lens can become cloudy and vision can become hazy again. This is not a recurrence of the cataract — the removed crystalline lens does not grow back. It is a common, benign occurrence, treated in a few minutes with a laser, without an incision or hospitalisation. Knowing this helps avoid unnecessary worry and ensures you know where this simple procedure can be performed.

07 · Risks

Risks

Risks and complications

• Intraocular infection — rare, but the most serious complication: an absolute emergency;
• Prolonged inflammation;
• Macular oedema, causing delayed visual loss and generally resolving with treatment;
• Rupture of the capsule that supports the intraocular lens during surgery, which may change how the procedure proceeds and the type of lens implanted;
• Retinal detachment, more common in people with high myopia — an emergency;
• Corneal oedema, temporary or, more rarely, persistent;
• Raised intraocular pressure;
• A residual correction different from that expected;
• Halos, glare or perception of a crescent of light, especially with certain lenses;
• Displacement or rotation of the intraocular lens, which may require another procedure;
• Secondary opacification of the capsule, treated with a laser;
• Worsened dry eye.

08 · Contraindications

Contraindications

Situations requiring particular assessment

• active eye infection or inflammation;
• a cataract without genuine functional difficulty;
• retinal or optic nerve disease limiting visual potential — this does not prohibit surgery, but requires a realistic outcome to be explained;
• uncontrolled glaucoma;
• a fragile cornea or low corneal endothelial cell density;
• poorly controlled diabetes or progressive retinopathy;
• treatment that alters iris behaviour, which must be reported;
• a history of refractive surgery, which changes the intraocular lens calculation;
• inability to use the prescribed drops, attend checks or access an ophthalmological emergency service;
• unrealistic expectations, particularly the hope of being completely free from glasses.

09 · Frequently asked questions

Frequently asked questions

Questions patients often ask