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What is a cataract?

A cataract occurs when the natural lens of the eye becomes hazy or opaque. The eye is like a camera with the lens at the front and retina at the back. If a cataract develops the transmission of light to the retina at the back of the eye is adversely affected, so leading to a reduction in vision. Cataracts are usually age related but can also be caused by trauma, medications such as steroids, medical conditions such as diabetes, and other factors.


Cataracts result in a reduction in vision. Patients may experience general blurring of their vision, glare at night especially with car head lights or a reduction in colour vision.

I will perform a full examination of your eye including testing your visual acuity, checking your intraocular pressure, examining your cataract and  carefully  looking at the back of your eye to check that there are no other conditions affecting your vision.

Careful measurements will be taken of your eye including the curvature of your cornea and the distance from the front to the back of your eye. This enables the optimum replacement lens to be chosen for your eye. Your ophthalmologist will then discuss cataract surgery with you, the potential benefits and the very small risk of complications.

Pre-operative assessment

How is cataract surgery performed?

Most cataract surgery is performed under local anaesthetic. A local anaesthetic injection means that you will feel no pain during the operation. Intravenous sedation can also usually be given to relax you during the procedure.


Cataract surgery is occasionally performed under topical anaesthetic (with drops) or general anaesthetic.


The anaesthetic injection is performed by an anaesthetist in the anaesthetic room.

After the anaesthetic you are wheeled on a comfortable bed into the operating theatre. You lie flat during the procedure. The theatre nurse will clean around your eye and place a sterile drape around it.


During the operation a nurse will be holding your hand. If you have any problems during the operation, such as needing to cough, you squeeze the nurse’s hand who will then inform the surgeon.

The operation takes about 15-20 minutes. A 2.2mm incision and a 1mm incision are made at the edge of your cornea (clear window of the eye). Your cataract is liquefied and aspirated out of your eye using a machine called a phacoemulsification machine.


A new clear transparent intraocular lens is then inserted into the eye in the same position as your original lens. A small antibiotic injection is given and the operation is over!

Modern intraocular lenses are made of acrylic or silicon. Most intraocular lenses are fixed focus lenses tailored to give you good distance vision without glasses. This means that even if you are long or short sighted, cataract surgery will give you good distance vision without glasses. A weak pair of glasses may further crispen your distance vision. It is usually necessary to wear glasses for reading.

Multifocal intraocular lenses are also available. These lenses can give you both distance and reading vision without the need to wear glasses. However the quality of the vision is often not so good when the lens is having to focus for both near and distance vision. In addition patients can often experience glare at night with multi focal lenses.

Cataract surgery is not a treatment for astigmatism. Astigmatism occurs when the eye is rugby ball shaped rather than football shaped. Most patients have a small degree of astigmatism. Cataract surgery can reduce the astigmatism that a patient has by careful placement of the incisions, extra partial thickness incisions or special intraocular lenses.

Type of intraocular lens

Type of intraocular lens

After the operation

After the operation you will sit back in the waiting area for light refreshments. The nurse will explain about post operative instructions.

Your vision may be a little blurred for the first day after the operation as your pupil will still be dilated. Objects will also appear quite bright. This will settle over the course of the first day or two.

You may be rung the day after the operation to check that there are no problems.

You may watch television, use the computer and go for gentle walks. You can bend over to lift up to 2Kg (about two bags of sugar).
You can drive after 7-10 days as long as your vision is good enough. You should avoid strenuous exercise or anything potentially dirty such as gardening for 4 weeks.

You may find it helpful to buy ‘off the peg’ reading glasses for the first few weeks after cataract surgery. You can be tested by your optician for new glasses six weeks after the operation.

You will be seen usually 2-3 weeks after the operation for a check up in clinic.

Frequently asked questions

Are cataracts treated by laser?

Cataracts are not treated by laser. A special machine called a phacoemulsifier is used to liquefy and aspirate the cataract.

Does the intraocular lens need replacing?
The intraocular lens does not need replacing. It stays in your eye for always.

How does the new intraocular lens stay in position?

The new lens is inserted in the eye in the same place (capsular bag) as your original cataractous lens was removed. There are two expandable arms which fix the new lens in position.

What is an after cataract?

After cataract is more correctly termed posterior capsule opacification. The posterior capsule is a clear membrane which sits directly behind the new intraocular lens. With time the posterior capsule can become thickened, hazy or opacified. This leads to a reduction in vision and blurring. Posterior capsule opacification can occur weeks to years after cataract surgery.

Posterior capsule opacification can easily be treated by laser. The laser makes a hole in the thickened membrane leading to an almost immediate improvement in vision. Laser treatment takes about 5 minutes and is painless. It rarely needs repeating.

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