Cataract Surgery

I do cataract surgery in three rather different settings. Much of it is part of retinal surgery: when I operate on a macular hole or a membrane at the back of the eye I usually remove the cataract at the same time, which gives me a clearer view, makes the retinal operation safer, and saves you a second operation a year later. Much of the rest is cataract that other surgeons have sent me – very dense lenses, eyes whose supporting structures are weak, pupils that will not dilate, and eyes that have had surgery or an injury before. The high-volume cataract units refer their difficult cases on, and I am one of the people they refer them to.

And some of it is ordinary, straightforward cataract surgery for people who simply want their cataracts dealt with, mostly in my private practice. If that is you, none of the complicated work above applies – it is the same operation, done the same way, and it is the commonest one I do in that setting.

What is a cataract and how is it treated?

The lens in the eye can become cloudy and hard, a condition known as a cataract. Cataracts can develop from normal ageing, from an eye injury, or if you have taken medications such as steroids. Cataracts may cause blurred vision, dulled vision, sensitivity to light and glare, and/or ghost images. If the cataract changes vision so much that it interferes with your daily life, the cataract may need to be removed. Surgery is the only way to remove a cataract. You can decide not to have the cataract removed. If you don’t have the surgery, your vision loss from the cataract would continue to get worse but would not cause permanent impairment.

How would removing the cataract affect my vision?

The goal of cataract surgery is to correct the decreased vision that was caused by the cataract. During the surgery, I would remove the cataract and put in a new artificial lens called an intraocular lens or IOL.

Cataract surgery will not correct other causes of decreased vision, such as glaucoma, diabetes, or age-related macular degeneration.

Most people still need to wear glasses or contact lenses after cataract surgery for either near and/or distance vision and/or astigmatism.

What types of IOLs are available?

There are IOLs available to treat nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. IOLs usually provide either near or distance vision: these single focus lenses are called monofocal IOLs. Some newer IOLs claim to provide for near, intermediate, and distance vision: these multiple focus lenses are called multifocal IOLs. IOLs that treat astigmatism are called toric IOLs. You can also have one eye corrected for near vision, and the other for distance vision, a choice called monovision.

Because I see lots of problems in people with multifocal lenses I do not use them myself. If you want a multifocal lens you will need to see a refractive surgeon.

In most cases I would advise a monofocal lens focussed for distance vision. I would expect that to give good distance vision without glasses, though a small glasses prescription may be needed for the very best driving vision, and glasses would be needed for reading and computer work.

You decide what you want the result to be. Choosing the lens that will get you there is my job.

It is worth knowing how accurate that aim is, because it is not perfect. The power of the lens is worked out from measurements of your eye, and in the largest study of this – more than 18,000 operations – the result landed within half a dioptre of the target in about 8 in every 10 eyes, and within a full dioptre in more than 95 in every 100. Half a dioptre is a weak prescription, the kind many people would not bother wearing; a full dioptre is one you would notice. Very short and very long eyes are harder to predict and do a little worse than that.

That is about as good as the maths currently gets, and it is why I will not promise you will be free of glasses.

What is astigmatism? Are there other treatments for it?

Patients with nearsightedness and farsightedness often also have astigmatism. An astigmatism is caused by an irregularly shaped cornea; instead of being round like a football, the cornea is shaped like a rugby ball. This can make your vision blurry.

Astigmatism can be reduced by glasses or contact lenses, by a toric IOL, by refractive surgery (LASIK or PRK), or by a limbal relaxing incision – a small cut in the cornea to make its shape rounder – done either at the same time as the cataract operation or separately. Any attempt at astigmatism reduction could result in over- or under-correction, in which case glasses, contact lenses, or another procedure may be needed.

I do not generally correct astigmatism as part of cataract surgery, for much the same reason I do not use multifocal lenses: I see too many people left unhappy by it. My view is that refractive surgery belongs with a refractive surgeon, who has ready access to a laser to correct an unexpected result. And given the accuracy described above – a fifth of eyes landing more than half a dioptre from target – this is where the maths shows we cannot promise. Other surgeons take a different view, so if you would like astigmatism correction, you are welcome to discuss it with me or to see a refractive surgeon.

What are the major risks of cataract surgery?

As with any surgery or medical intervention things can go wrong, and I cannot tell you about every risk: operations and procedures can result in unsuccessful results, complications, injury, or even death, from both known and unknown causes. The major risks of cataract surgery include, but are not limited to, bleeding; infection; injury to parts of the eye and nearby structures from the anaesthesia, the operation itself, or pieces of the lens that cannot be removed; high eye pressure; a detached retina; and a droopy eyelid.

The figures below are national ones rather than my own. They come from the Royal College of Ophthalmologists’ National Ophthalmology Database, which audits cataract surgery across the United Kingdom – around 550,000 operations a year – and from the Cataract National Dataset that preceded it.

They describe straightforward cataract surgery, and only that. The national audit deliberately leaves out operations where the cataract is removed as part of something larger – combined with a vitrectomy, for instance – and leaves out cataracts caused by an injury. So if your operation is one of the more complex ones described at the top of this page, these are the wrong numbers for your eye: the risks are higher, and I will go through them with you rather than leave you to work it out from a national average.

Depending upon your eye and the type of IOL, you may have increased night glare or halos, double vision, ghost images, impaired depth perception, blurry vision, and trouble driving at night. The monofocal lenses I use have fewer of these problems than multifocal lenses do. They are also made of hydrophobic acrylic, which does not carry the risk of clouding that hydrophilic acrylic lenses can develop, particularly in eyes that later need retinal surgery.

Depending on how the operation goes I might not be able to use the lens I had planned. In addition, the IOL may later need to be repositioned or replaced.

Depending upon the type of anaesthesia, other risks are possible, including cardiac and respiratory problems, and, in rare cases, death. For local anaesthesia this is an extremely rare complication.

There is no guarantee that cataract surgery will improve your vision, and it is possible that the surgery or the anaesthetic could make it worse. Some complications appear weeks, months or even years later. In rare situations they can lead to poor vision, total loss of vision, or loss of the eye, and further treatment or surgery may be needed to deal with them.

The main risks at a glance

The grid below is 100 people who have the operation; the shaded dots are those affected.

The serious complications of cataract surgery are all less common than 1 in every 100, so a grid of a hundred people cannot draw them honestly. They are listed below instead.

Frosting of the capsule behind the lens implant is left out of these bands: it is far commoner than anything in them, and it is a normal part of healing rather than a complication. There is more about it at the end of this page.

Common (up to 1 in every 20)

• Inflammation inside the eye – about 2 in every 100
• Swelling at the centre of the retina (cystoid macular oedema) – about 1 to 2 in every 100, usually temporary
• Needing glasses for some tasks

Uncommon (up to 1 in every 100)

• The capsule behind the lens tearing during the operation – about 7 in every 1,000. This is the complication surgeons watch most closely, because it makes all of the others more likely
• Losing two lines or more of vision – about 5 in every 1,000
• A severe drop in vision – about 2 in every 1,000
• Pieces of lens dropping into the back of the eye, needing a second operation – about 2 in every 1,000

Rare (up to 1 in every 1,000)

• Infection inside the eye (endophthalmitis) – about 4 in every 10,000
• Retinal detachment – about 7 in every 10,000 in the first year, and more likely in short-sighted eyes or if the capsule tears during surgery
• The lens implant needing to be repositioned or exchanged

Very rare (up to 1 in every 10,000)

• Loss of the eye
• Severe inflammation in the other eye (sympathetic ophthalmia)

Whilst I have gone through lots of complications that can occur, cataract surgery is the most commonly performed operation there is, and most people who have it have no problems at all and see better afterwards than they did before.

YAG capsulotomy

Frosting of the capsule behind the lens implant is the commonest thing to need attention after cataract surgery, and the longer anyone follows a group of patients the more of them have needed the laser. It is not a complication and not a sign anything has gone wrong, and it is easily treated with a YAG laser in the outpatient clinic.

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