One of the most common questions I am asked before cataract surgery is not really about the operation itself.

It is:

“What will I actually be able to see afterwards?”

That is a very reasonable question. Cataract surgery is highly successful at restoring clear vision, but the type of vision you have afterwards depends on more than simply removing the cataract. Your eyes, your glasses prescription, your astigmatism and, importantly, the type of lens implanted inside the eye all play a role.

When I discuss cataract surgery with patients, I therefore spend a lot of time talking about what they want to do without glasses after surgery.

First: cataract surgery should make your vision clearer

A cataract is a clouding of the natural lens inside the eye. As it progresses, vision can become blurred, colours may appear less vibrant and glare can become increasingly troublesome.

Many patients particularly notice difficulty with:

• driving at night

• recognising road signs

• glare from headlights

• reading television subtitles

• seeing in dimly lit restaurants

• needing increasingly strong lighting to read

During cataract surgery, I remove the cloudy natural lens and replace it with a clear artificial lens, known as an intraocular lens or IOL.

Removing the cataract addresses the cloudiness. The next decision is how we want to focus the eye afterwards.

And this is where modern cataract surgery becomes much more personalised.

Will I still need glasses after cataract surgery?

Possibly.

There is no single lens that is perfect for every patient.

For some people, the priority is simply having excellent quality distance vision and they are completely comfortable wearing reading glasses.

Other patients would really like to use a computer without glasses.

Others want as much freedom from glasses as possible for driving, computer work, reading and using their phone.

I think the best way to choose a lens is therefore not to start with the technology.

I usually start by asking:

“What would you most like to be able to do without glasses?”

Distance vision: driving and watching television

Most modern lens options can provide very good distance vision when the eye is otherwise healthy and we achieve the intended refractive result.

With a monofocal lens, I can usually aim the eye primarily for one distance.

For most patients that means distance vision.

This can provide excellent vision for activities such as:

• driving

• watching television

• sport

• walking

• recognising faces across a room

The trade-off is that you will usually need glasses for reading and often for computer work.

For someone who has worn glasses all their life, this can still represent a significant reduction in dependence on glasses.

Computer vision

This has become increasingly important.

A lot of people tell me:

“I don’t mind wearing glasses for very small print, but I don’t want to put glasses on every time I look at my computer.”

This is where an extended depth of focus, or EDOF, lens can be useful.

An EDOF lens aims to provide a broader range of vision than a standard monofocal lens.

Typically, the goal is good:

distance → intermediate vision

That means activities such as driving, television and computer use can often be performed without glasses.

However, I am careful not to promise reading vision with an EDOF lens.

Most patients should expect to need glasses for smaller print and prolonged reading.

The advantage is that EDOF lenses generally produce fewer night-time visual disturbances than lenses designed to provide a greater range of near vision.

Reading and using your phone

If being able to read without glasses is a high priority, we can consider a trifocal lens.

Trifocal lenses divide light in a way that provides three useful focal ranges:

distance → intermediate → near

The aim is to reduce dependence on glasses for activities such as:

• driving

• computer work

• checking your phone

• reading menus

• shopping

• reading books

Many patients with trifocal lenses rarely use glasses.

However, there is a trade-off.

Trifocal lenses can produce visual phenomena such as haloes or glare around lights, particularly at night.

For most patients these become much less noticeable as the brain adapts, but they are an important part of the discussion before surgery.

This is why I do not think cataract lens selection should simply be a question of choosing the lens that provides the widest range of vision.

The best lens is the one whose advantages and compromises best suit that particular patient.

What about night driving?

Night vision is an important consideration, particularly for patients who do a lot of night driving.

Even with successful cataract surgery, you may initially notice some glare while the eye is healing.

The type of implanted lens can also influence night vision.

A monofocal lens generally produces the fewest optical disturbances.

An EDOF lens can provide greater range of vision while generally maintaining relatively good night-time visual quality.

A trifocal lens provides greater potential freedom from reading glasses, but haloes around headlights and streetlights are more common.

There is therefore always a balance between range of vision and optical quality.

Neither choice is automatically right or wrong.

What if I have astigmatism?

Astigmatism is extremely common.

If you have significant corneal astigmatism and we do not correct it during cataract surgery, your distance vision may still be blurred without glasses even though the cataract has been removed.

For suitable patients, I can use a toric intraocular lens to correct astigmatism at the same time as cataract surgery.

Toric correction can be incorporated into monofocal, EDOF and trifocal lens strategies.

This is one of the reasons accurate measurements before surgery are so important.

Will my vision be perfect immediately after surgery?

Usually not.

Many patients see surprisingly well within the first day or two, but I tell patients not to judge the final result too early.

During the first few days you may notice:

• mildly blurred or hazy vision

• fluctuating vision

• glare

• a gritty or foreign-body sensation

• mild redness

• differences between your two eyes

The eye then gradually settles.

For most patients, vision improves considerably during the first week, but refinement can continue over several weeks.

If you have sequential surgery, there can also be an unusual period between operations where one eye has been corrected and the other still has a cataract.

What if there is still a small glasses prescription afterwards?

Modern measurements are extremely accurate, but no cataract operation can guarantee that the eye will finish with exactly zero prescription.

The biological response of every eye is slightly different.

Occasionally a patient is left with a small amount of:

• short-sightedness

• long-sightedness

• astigmatism

For many people this is so small that it causes no significant problem.

If the residual prescription is troublesome, however, there may be options to improve it.

Depending on the individual eye, these can include glasses, laser vision correction or, less commonly, another lens-based procedure.

I think it is important for patients to understand this before surgery rather than assuming cataract surgery guarantees perfect unaided vision.

The most important question isn’t “Which lens is best?”

It is:

“Which lens is best for me?”

A patient who loves reading novels without glasses may make a very different choice from someone who drives extensively at night.

Similarly, a patient who spends eight hours each day on a computer may have different priorities from someone who is completely comfortable using reading glasses.

There are also situations where the health of the eye influences what lens I recommend.

Conditions affecting the cornea, retina or optic nerve may make some lens technologies less suitable.

That is why I prefer to make the decision after examining the eye, reviewing the measurements and talking about the patient’s lifestyle.

How I think about the three main options

The table makes the differences look simple, but in reality there is much more nuance.

Your prescription, eye health, pupil size, corneal shape, occupation and expectations all matter.

My aim with cataract surgery

My goal is not simply to remove the cataract.

It is to understand how you use your eyes and plan the surgery around the type of vision that matters most to you.

For one patient, success might mean driving confidently at night without glasses.

For another, it might mean sitting at a computer all day without reaching for reading glasses.

For someone else, the priority may be reading their phone, a menu and a book with as little dependence on glasses as possible.

Modern cataract surgery gives us more options than ever before.

The important part is choosing those options carefully.

Before your surgery, think about the three things you most want to be able to do without glasses.

That simple question often makes choosing the right lens considerably easier.

Dr Geoffrey Ryan is an ophthalmologist with subspecialty training in cornea, glaucoma, cataract and refractive surgery. Lens suitability and visual outcomes vary between patients, and an individual assessment is required before determining the most appropriate treatment.