Choosing a lens for cataract surgery: monofocal, multifocal or toric?

Once a patient has decided to have cataract surgery, a new question often causes confusion: "Which lens should I choose? I've heard of a lens that means no more glasses, a lens for astigmatism, and a standard lens. Which is best?" The honest answer is that there is no lens that is "best" for everyone. There is a lens that is best for you, depending on your eye, your way of life, what you expect from the operation, and which side effects you can accept.

What does the implanted lens actually do?

In cataract surgery we remove the natural lens that has become cloudy and replace it with a clear artificial lens that stays in the eye for life. All modern lenses restore the clarity that the cataract was blocking. The types differ in something else: at which distances they focus vision, and therefore how much you will need glasses after surgery.

The natural lens of a young person changes shape to see near and far. An artificial lens does not change. So the different types of lens try to make up for this ability in different ways, and each way has a price.

The monofocal lens: the usual choice

This lens focuses vision at one distance, usually far. The patient sees distant objects clearly without glasses in most cases, and needs reading glasses for near work.

Its advantage is that it gives the sharpest possible image at the chosen distance, with the fewest halos around lights. That is why it remains the usual choice in most operations. The British guideline from the National Institute for Health and Care Excellence recommends not offering multifocal lenses in operations covered by its health service (National Institute for Health and Care Excellence, 2017).

Monovision: one eye for far, one eye for near

Here two monofocal lenses are used, but one eye is set for distance and the other for a slightly closer distance. The brain uses the right eye for each distance. This approach particularly suits people who were used to it before surgery, either with contact lenses or naturally, which is what the British guideline recommends for these patients (National Institute for Health and Care Excellence, 2017).

In a clinical trial comparing this approach with multifocal lenses, complete freedom from glasses was less common with monovision: about a quarter of patients, compared with about three quarters with multifocal lenses. But during the first year, about 6% of patients with multifocal lenses needed a lens exchange in another operation, while nobody in the monovision group needed one (Wilkins et al., 2013).

Multifocal lenses: less dependence on glasses, at a visual price

These lenses split the light entering the eye across more than one distance: far and near (bifocal), or far, intermediate and near (trifocal). The aim is to reduce the need for glasses in most daily activities.

In a Cochrane review of 20 clinical trials, distance vision was similar with multifocal and monofocal lenses. Near vision was better, and dependence on glasses lower, with multifocal lenses. But halos around lights were clearly more common with them, and so was glare (de Silva et al., 2016). The researchers concluded that motivation to be free of glasses is usually the deciding factor in the choice (de Silva et al., 2016).

Extended depth of focus lenses: a focus on intermediate distance

This is a newer type that extends the range of clear vision from far to intermediate distance (a computer screen, a car dashboard, the face of the person in front of you), but it does not usually give the same near clarity as trifocal lenses.

In an analysis of 27 clinical trials, intermediate vision was better with these lenses than with monofocal lenses. Near vision was better with trifocal lenses. Distance vision was similar across all types (Cho et al., 2022). This analysis found no definite differences in halos and glare between the types (Cho et al., 2022), whereas the earlier Cochrane review did find them (de Silva et al., 2016). In other words, the evidence is not identical, and personal experience varies from patient to patient.

Toric lenses: when you have astigmatism

Astigmatism means the surface of the cornea is not perfectly round, so the image looks blurred or stretched in one direction. A toric lens corrects this astigmatism from inside the eye, and can be monofocal or one of the other types.

In a review of 13 clinical trials, strong evidence showed that toric lenses give clearer distance vision without glasses and less dependence on glasses for distance than standard lenses, without a clear increase in complications (Kessel et al., 2016). The European Society of Cataract and Refractive Surgeons recommends them when corneal astigmatism is one diopter or more (European Society of Cataract and Refractive Surgeons, 2024). The doctor decides this from measurements of the cornea before surgery.

A short comparison

Who needs to be careful before choosing a multifocal lens?

There are groups of patients with whom we take extra care before choosing a multifocal lens, and explain things in more detail:

• People with a disease of the retina or macula, or at risk of one, such as diabetic retinopathy, macular degeneration, or an epiretinal membrane. Many doctors are cautious with these lenses in such patients, because they may reduce contrast sensitivity, the ability to distinguish faint shades of gray and detail in poor light. However, a scientific review did not find enough evidence to rule them out completely in these patients, while confirming that research on this subject is still limited (Grzybowski et al., 2020). So we discuss with each patient the state of their macula now and the chance that it will be affected later. For people with diabetes in particular, see our article on cataract surgery in diabetes.
• People who drive a lot at night, because halos and glare around lights are more common with these lenses (de Silva et al., 2016), and car headlights at night are one of the situations where they show most.
• People who expect perfect vision without any glasses in all conditions. The realistic goal is less dependence on glasses, not guaranteed freedom from them.

What if I am not happy with the lens after surgery?

This happens in a proportion of patients, especially with multifocal lenses. In a study of patients unhappy with these lenses, the most common complaints were blurred vision and light phenomena such as halos. The main causes were residual short-sightedness, long-sightedness or astigmatism, clouding of the capsule behind the lens, and a large pupil. The cause could be treated in most patients (about 84% of eyes); the most common solutions were laser vision correction, glasses, and laser for capsule clouding, while only about 4% needed a lens exchange (de Vries et al., 2011).

Useful questions to ask your surgeon

• Does the state of my retina and macula allow every type of lens?
• Do I have astigmatism that is worth correcting with a toric lens?
• Which distance do I most need to see without glasses in daily life: driving, the computer, or reading?
• What side effects are expected with this particular lens, and what can we do if they bother me?

Questions patients often ask

Is the most expensive lens the best?

No. The price reflects the lens technology, but it does not mean it is the most suitable for your eye. A monofocal lens gives the sharpest vision at one distance with the fewest side effects (de Silva et al., 2016), and may be the best choice for many patients.

Will a multifocal lens free me from glasses completely?

It clearly increases the chance of being free of glasses, but it does not guarantee it (Wilkins et al., 2013; de Silva et al., 2016). You may need glasses for some tasks or in poor light.

Can the lens be changed later?

It can, but that is a new operation with its own risks. Fortunately, most causes of dissatisfaction can be solved without exchanging the lens (de Vries et al., 2011). That is why the first choice should be well considered.

Does the lens power differ from one eye to the other?

Yes. The lens power is calculated for each eye separately from precise measurements before surgery. We explain the preparation steps in our article on cataract surgery.

Summary

Choosing the implanted lens is a shared decision between you and your surgeon. A monofocal lens gives the sharpest image at one distance, with reading glasses. Multifocal and extended depth of focus lenses reduce the need for glasses, at the cost of a greater chance of halos and glare. Toric lenses correct astigmatism from inside the eye. The right decision is based on the health of the retina, your daily life, and your realistic expectations. We make sure each patient knows what the lens will and will not do before they choose.

This information is for health education and does not replace a medical examination.