Mr Velota Sung FRCS(Ed), FRCOphth, MSc(Warwick)

Cataract surgery

Rayner C-flex lens implant

Cataract surgery is an operation to remove the cloudy lens inside the eye and replace it with an artificial lens implant.

Over the last two decades, the technology of the phacoemulsification machine and the technique for cataract surgery have improved dramatically. Cataract surgery is now a very safe procedure, commonly performed under local anaesthetic as a day case. Patients can expect a 99% success rate with very low risk of complications under the hands of experienced eye surgeons.

What causes cataracts?

A slit-lamp image of an eye with a brownish cloudy cataract inside.

Cataracts are commonly formed as part of the ageing process. The crystalline lens inside the eye is usually clear; over the years, the protein inside the lens undergoes an ageing process that causes gradual cloudiness and impairs vision. It is estimated that one-third of patients aged 65 or above have cataracts in one or both eyes in the UK.

Some people can develop cataracts earlier due to other systemic or eye conditions, e.g. diabetes, use of systemic or topical steroid medicines, chronic eye inflammation (uveitis), ocular trauma, previous eye surgery, etc.

Children or newborn babies can also develop cataracts as an isolated or part of a systemic genetic condition. However, this is very rare.

What are the symptoms of cataracts?

Patients commonly complain of blurry vision for distance or near vision, like looking through frosted glasses. This is more obvious when cataracts develop at a different speed between the two eyes.

Patients can also complain of glare under bright sunlight or when driving at night, when the headlights from the opposite side cause extreme glaring, making driving dangerous.

Cataracts can affect people differently depending on their jobs and hobbies. When people are required to perform minuscule tasks, they may complain of visual difficulties earlier than others. For example, watchmakers may complain of visual problems earlier than others.

Therefore, a person's need for a cataract operation depends very much on the demands of daily vision.

Who needs cataract surgery?

When cataracts have caused patients significant visual difficulties, a cataract operation is warranted.

In patients with angle-closure glaucoma, the crystalline lens is too large for the overall size of the eyes. This can cause gradual narrowing of the anterior chamber drainage angle as the lens grows bulkier with age. This can cause acute raised eye pressure and, hence, acute angle-closure glaucoma attack. An early cataract operation would be necessary if the angle is still narrow after laser iridotomy treatment.

How to prepare for cataract operation?

Biometry test with Zeiss IOL Master 500

Patients will require a Biometry test before cataract surgery. Biometry is a test to measure the dimension, including the cornea's curvature and the eyeball's length, to determine the lens implant power.

Patients need to ensure no active infection (e.g. leg ulcers) in the body before undergoing a cataract operation. Patients with blepharitis (chronic infection of the eyelids) should perform vigorous lid hygiene before cataract surgery to reduce the local bacteria load and the risk of postoperative infection. In severe blepharitis, antibiotic treatment may be necessary before the operation.

Patients do not need to stop aspirin or warfarin before surgery. However, for patients on warfarin, the allowable INR level before cataract surgery depends on surgeons, so this must be discussed with your eye specialists. In general, the INR must not be higher than four before surgery to reduce the risk of severe bleeding at the time of surgery.

Patients with high blood pressure should ensure their blood pressure is under reasonable control. Excessively high blood pressure can increase the risk of complications during surgery.

What to expect on the day of the operation?

Most cataract operations are performed under local anaesthetics and as day cases. You can still eat and drink normally, but it is advisable not to overeat, as this may cause indigestion when you have to lie down for some time during the operation. You should also take your regular medications as usual unless your GP or eye specialists have advised otherwise. This is particularly important for medicines for blood pressure and diabetes.

On admission, the nurses will instil multiple eye drops in your eyes to dilate your pupil in preparation for surgery. You will be taken to the theatre, and more eye drops will be put into your eyes to numb your eyes before surgery. Most eye surgeons will give you a small local anaesthetic injection before the operation. Your eye surgeon will use an antiseptic solution to clean the eyelids and the surrounding area of your eye, and a piece of sticky plastic sheet will be used to cover your face so only the eye undergoing operation is exposed. A small speculum made of metal wire will be used to keep your eye open. When the operation is underway, you should look directly into the bright light from the microscope. Many patients say they can see multicoloured patterns moving around before their eyes. You will also hear noises from the machine and even water dripping down the side of your face.

The operation usually takes 10-20 minutes. At the end of the operation, the surgeons will pull the plastic sheet away from your face and place an eye pad and a plastic shield on your eye. You will be taken back to the ward or day case unit, and the nurses will give you the eye drops to use after the operation. You should be able to leave the clinic/hospital and go home. You should only disturb the eye pad and shield the next day after the operation.